Add Certification merge logic

Issue-ID: DCAEGEN2-2253
Signed-off-by: Tomasz Wrobel <tomasz.wrobel@nokia.com>
Change-Id: I4157ce71373b41d9f7ee03b76d407ec7a2b17ec3

50 files changed, 1816 insertions, 245 deletions

diff --git a/trustStoreMerger/Dockerfile b/trustStoreMerger/Dockerfile
index 63d15c42..8f0f2481 100644
--- a/trustStoreMerger/Dockerfile
+++ b/trustStoreMerger/Dockerfile
@@ -10,4 +10,7 @@ USER truststoreMerger:onap
 
 COPY target/oom-truststore-merger-${VERSION}.jar ./opt/onap/oom/truststoremerger/oom-truststore-merger.jar
 
+#Run as root allow to manage certificates provided by other containers. It should be change in future
+USER root
+
 ENTRYPOINT ["java","-jar","./opt/onap/oom/truststoremerger/oom-truststore-merger.jar"]
diff --git a/trustStoreMerger/pom.xml b/trustStoreMerger/pom.xml
index 201365ca..fd2aff05 100644
--- a/trustStoreMerger/pom.xml
+++ b/trustStoreMerger/pom.xml
@@ -165,5 +165,9 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-log4j2</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.bouncycastle</groupId>
+            <artifactId>bcpkix-jdk15on</artifactId>
+        </dependency>
     </dependencies>
 </project>
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/TrustStoreMerger.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/TrustStoreMerger.java
index 98c67ba8..c8cc84df 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/TrustStoreMerger.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/TrustStoreMerger.java
@@ -21,11 +21,12 @@ package org.onap.oom.truststoremerger;
 
 import org.onap.oom.truststoremerger.api.ExitStatus;
 import org.onap.oom.truststoremerger.api.ExitableException;
-import org.onap.oom.truststoremerger.certification.file.TruststoreFile;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.model.Truststore;
 import org.onap.oom.truststoremerger.certification.file.provider.FileManager;
 import org.onap.oom.truststoremerger.certification.file.provider.PasswordReader;
-import org.onap.oom.truststoremerger.certification.file.provider.TruststoreFileFactory;
-import org.onap.oom.truststoremerger.certification.file.provider.TruststoreFilesListProvider;
+import org.onap.oom.truststoremerger.certification.file.TruststoreFileFactory;
+import org.onap.oom.truststoremerger.certification.file.TruststoreFilesListProvider;
 import org.onap.oom.truststoremerger.certification.path.EnvProvider;
 import org.onap.oom.truststoremerger.certification.path.TruststoresPathsProvider;
 import org.onap.oom.truststoremerger.configuration.MergerConfiguration;
@@ -33,9 +34,15 @@ import org.onap.oom.truststoremerger.configuration.MergerConfigurationFactory;
 import org.onap.oom.truststoremerger.certification.path.PathValidator;
 
 import java.util.List;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 class TrustStoreMerger {
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(TrustStoreMerger.class);
+    private static final int FIRST_TRUSTSTORE_INDEX = 0;
+    private static final int SECOND_TRUSTSTORE_INDEX = 1;
+
     private final AppExitHandler appExitHandler;
 
     TrustStoreMerger(AppExitHandler appExitHandler) {
@@ -47,28 +54,42 @@ class TrustStoreMerger {
             mergeTruststores();
             appExitHandler.exit(ExitStatus.SUCCESS);
         } catch (ExitableException e) {
+            LOGGER.error("Truststore Merger fails in execution: ", e);
             appExitHandler.exit(e.applicationExitStatus());
         }
     }
 
     private void mergeTruststores() throws ExitableException {
         MergerConfiguration configuration = loadConfiguration();
-        List<TruststoreFile> truststoreFilesList = getTruststoreFilesList(configuration);
+        List<Truststore> truststoreFilesList = getTruststoreFilesList(configuration);
+
+        Truststore baseFile = truststoreFilesList.get(FIRST_TRUSTSTORE_INDEX);
+        baseFile.createBackup();
+
+        for (int i = SECOND_TRUSTSTORE_INDEX; i < truststoreFilesList.size(); i++) {
+            List<CertificateWithAlias> certificateWrappers = truststoreFilesList.get(i).getCertificates();
+            baseFile.addCertificate(certificateWrappers);
+        }
+
+        baseFile.saveFile();
     }
 
     private MergerConfiguration loadConfiguration() throws ExitableException {
-        TruststoresPathsProvider truststoresPathsProvider = new TruststoresPathsProvider(new EnvProvider(), new PathValidator());
+        TruststoresPathsProvider truststoresPathsProvider = new TruststoresPathsProvider(new EnvProvider(),
+            new PathValidator());
         MergerConfigurationFactory factory = new MergerConfigurationFactory(truststoresPathsProvider);
         return factory.createConfiguration();
     }
 
-    private List<TruststoreFile> getTruststoreFilesList(MergerConfiguration configuration) throws ExitableException {
-        TruststoreFileFactory truststoreFileFactory = new TruststoreFileFactory(new FileManager(), new PasswordReader());
-        TruststoreFilesListProvider truststoreFilesListProvider = new TruststoreFilesListProvider(truststoreFileFactory);
+    private List<Truststore> getTruststoreFilesList(MergerConfiguration configuration) throws ExitableException {
+        TruststoreFileFactory truststoreFileFactory = new TruststoreFileFactory(new FileManager(),
+            new PasswordReader());
+        TruststoreFilesListProvider truststoreFilesListProvider = new TruststoreFilesListProvider(
+            truststoreFileFactory);
         return truststoreFilesListProvider
-                .getTruststoreFilesList(
-                        configuration.getTruststoreFilePaths(),
-                        configuration.getTruststoreFilePasswordPaths()
-                );
+            .getTruststoreFilesList(
+                configuration.getTruststoreFilePaths(),
+                configuration.getTruststoreFilePasswordPaths()
+            );
     }
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/CertificateConstants.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/CertificateConstants.java
new file mode 100644
index 00000000..68c5d13c
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/CertificateConstants.java
@@ -0,0 +1,29 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.api;
+
+public class CertificateConstants {
+
+    public static final String JKS_INSTANCE = "JKS";
+    public static final String PKCS12_INSTANCE = "PKCS12";
+    public static final String X_509_CERTIFICATE = "X.509";
+    public static final String BOUNCY_CASTLE_PROVIDER = "BC";
+
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ConfigurationEnvs.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ConfigurationEnvs.java
index 13c8c726..f6f8bbba 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ConfigurationEnvs.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ConfigurationEnvs.java
@@ -21,6 +21,6 @@ package org.onap.oom.truststoremerger.api;
 
 public class ConfigurationEnvs {
 
-    public static final String TRUSTSTORES_ENV = "TRUSTSTORES";
-    public static final String TRUSTSTORES_PASSWORDS_ENV = "TRUSTSTORES_PASSWORDS";
+    public static final String TRUSTSTORES_PATHS_ENV = "TRUSTSTORES_PATHS";
+    public static final String TRUSTSTORES_PASSWORDS_PATHS_ENV = "TRUSTSTORES_PASSWORDS_PATHS";
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ExitStatus.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ExitStatus.java
index d0c3b2f0..b9111bf9 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ExitStatus.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ExitStatus.java
@@ -25,7 +25,15 @@ public enum ExitStatus {
     TRUSTSTORES_PATHS_PROVIDER_EXCEPTION(1, "Invalid paths in environment variables"),
     MERGER_CONFIGURATION_EXCEPTION(2, "Invalid merger configuration"),
     TRUSTSTORE_FILE_FACTORY_EXCEPTION(3, "Invalid truststore file-password pair"),
-    PASSWORD_READER_EXCEPTION(4, "Cannot read password from file");
+    PASSWORD_READER_EXCEPTION(4, "Cannot read password from file"),
+    CREATE_BACKUP_EXCEPTION(5, "Cannot create backup file"),
+    KEYSTORE_INSTANCE_EXCEPTION(6, "Cannot initialize keystore instance"),
+    TRUSTSTORE_LOAD_FILE_EXCEPTION(7, "Cannot load truststore file"),
+    TRUSTSTORE_DATA_OPERATION_EXCEPTION(8, "Cannot operate on truststore data"),
+    MISSING_TRUSTSTORE_EXCEPTION(9, "Missing truststore certificates in provided file"),
+    ALIAS_CONFLICT_EXCEPTION(10, "Alias conflict detected"),
+    WRITE_TRUSTSTORE_FILE_EXCEPTION(11, "Cannot save truststore file");
+
 
     private final int value;
     private final String message;
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ExitableException.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ExitableException.java
index 3cc46730..ec28d466 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ExitableException.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/api/ExitableException.java
@@ -35,5 +35,6 @@ public class ExitableException extends Exception {
 
     public ExitStatus applicationExitStatus() {
         return exitStatus;
-    };
+    }
+
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/TruststoreFileFactory.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/TruststoreFileFactory.java
new file mode 100644
index 00000000..d93409b6
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/TruststoreFileFactory.java
@@ -0,0 +1,99 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file;
+
+import org.onap.oom.truststoremerger.certification.file.model.JavaTruststore;
+import org.onap.oom.truststoremerger.certification.file.model.PemTruststore;
+import org.onap.oom.truststoremerger.certification.file.model.Truststore;
+
+import java.io.File;
+import org.onap.oom.truststoremerger.certification.file.exception.KeystoreInstanceException;
+import org.onap.oom.truststoremerger.certification.file.exception.LoadTruststoreException;
+import org.onap.oom.truststoremerger.certification.file.exception.PasswordReaderException;
+import org.onap.oom.truststoremerger.certification.file.exception.TruststoreFileFactoryException;
+import org.onap.oom.truststoremerger.certification.file.provider.CertificateStoreControllerFactory;
+import org.onap.oom.truststoremerger.certification.file.provider.FileManager;
+import org.onap.oom.truststoremerger.certification.file.provider.JavaCertificateStoreController;
+import org.onap.oom.truststoremerger.certification.file.provider.PasswordReader;
+import org.onap.oom.truststoremerger.certification.file.provider.PemCertificateController;
+
+public class TruststoreFileFactory {
+
+    private static final String JKS_EXTENSION = ".jks";
+    private static final String P12_EXTENSION = ".p12";
+    private static final String PEM_EXTENSION = ".pem";
+    private static final String FILE_DOES_NOT_EXIST_MSG_TEMPLATE = "File: %s does not exist";
+    private static final String UNKNOWN_TRUSTSTORE_TYPE_MSG_TEMPLATE = "Unknown truststore extension type: %s";
+
+    private final FileManager fileManager;
+    private final PasswordReader passwordReader;
+    private final CertificateStoreControllerFactory certificateStoreControllerFactory =
+        new CertificateStoreControllerFactory();
+
+    public TruststoreFileFactory(FileManager fileManager, PasswordReader passwordReader) {
+        this.fileManager = fileManager;
+        this.passwordReader = passwordReader;
+    }
+
+    public Truststore create(String truststoreFilePath, String truststorePasswordPath)
+        throws TruststoreFileFactoryException, PasswordReaderException, KeystoreInstanceException, LoadTruststoreException {
+        File truststoreFile = new File(truststoreFilePath);
+        if (!fileManager.checkIfFileExists(truststoreFile)) {
+            throw new TruststoreFileFactoryException(String.format(FILE_DOES_NOT_EXIST_MSG_TEMPLATE, truststoreFile));
+        }
+        return createTypedTruststore(truststoreFile, truststorePasswordPath);
+    }
+
+    private Truststore createTypedTruststore(File truststoreFile, String truststorePasswordPath)
+        throws KeystoreInstanceException, PasswordReaderException, LoadTruststoreException, TruststoreFileFactoryException {
+        String extension = fileManager.getExtension(truststoreFile);
+        switch (extension) {
+            case JKS_EXTENSION:
+                return createJksTruststore(truststoreFile, truststorePasswordPath);
+            case P12_EXTENSION:
+                return createP12Truststore(truststoreFile, truststorePasswordPath);
+            case PEM_EXTENSION:
+                return createPemTruststore(truststoreFile);
+            default:
+                throw new TruststoreFileFactoryException(
+                    String.format(UNKNOWN_TRUSTSTORE_TYPE_MSG_TEMPLATE, extension));
+        }
+    }
+
+    private JavaTruststore createJksTruststore(File truststoreFile, String truststorePasswordPath)
+        throws PasswordReaderException, LoadTruststoreException, KeystoreInstanceException {
+        String password = passwordReader.readPassword(new File(truststorePasswordPath));
+        JavaCertificateStoreController storeController = certificateStoreControllerFactory
+            .createLoadedJksCertificateStoreController(truststoreFile, password);
+        return new JavaTruststore(truststoreFile, storeController);
+    }
+
+    private JavaTruststore createP12Truststore(File truststoreFile, String truststorePasswordPath)
+        throws LoadTruststoreException, KeystoreInstanceException, PasswordReaderException {
+        String password = passwordReader.readPassword(new File(truststorePasswordPath));
+        JavaCertificateStoreController storeController = certificateStoreControllerFactory
+            .createLoadedPkcs12CertificateStoreController(truststoreFile, password);
+        return new JavaTruststore(truststoreFile, storeController);
+    }
+
+    private PemTruststore createPemTruststore(File truststoreFile) {
+        return new PemTruststore(truststoreFile, new PemCertificateController(truststoreFile));
+    }
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFilesListProvider.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/TruststoreFilesListProvider.java
index 2f5356d5..92e3c2a8 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFilesListProvider.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/TruststoreFilesListProvider.java
@@ -17,13 +17,16 @@
  * ============LICENSE_END=========================================================
  */
 
-package org.onap.oom.truststoremerger.certification.file.provider;
+package org.onap.oom.truststoremerger.certification.file;
 
-import org.onap.oom.truststoremerger.certification.file.TruststoreFile;
+import org.onap.oom.truststoremerger.certification.file.model.Truststore;
 
 import java.util.ArrayList;
-import java.util.Iterator;
 import java.util.List;
+import org.onap.oom.truststoremerger.certification.file.exception.KeystoreInstanceException;
+import org.onap.oom.truststoremerger.certification.file.exception.LoadTruststoreException;
+import org.onap.oom.truststoremerger.certification.file.exception.PasswordReaderException;
+import org.onap.oom.truststoremerger.certification.file.exception.TruststoreFileFactoryException;
 
 public class TruststoreFilesListProvider {
 
@@ -33,16 +36,16 @@ public class TruststoreFilesListProvider {
         this.truststoreFileFactory = truststoreFileFactory;
     }
 
-    public List<TruststoreFile> getTruststoreFilesList(List<String> truststoreFilePaths,
-                                                       List<String> truststoreFilePasswordPaths)
-            throws PasswordReaderException, TruststoreFileFactoryException {
-        List<TruststoreFile> truststoreFilesList = new ArrayList<>();
+    public List<Truststore> getTruststoreFilesList(List<String> truststoreFilePaths,
+        List<String> truststoreFilePasswordPaths)
+        throws LoadTruststoreException, PasswordReaderException, TruststoreFileFactoryException, KeystoreInstanceException {
+        List<Truststore> truststoreFilesList = new ArrayList<>();
         for (int i = 0; i < truststoreFilePaths.size(); i++) {
             String truststorePath = truststoreFilePaths.get(i);
             String passwordPath = truststoreFilePasswordPaths.get(i);
 
-            TruststoreFile truststoreFile = truststoreFileFactory.create(truststorePath, passwordPath);
-            truststoreFilesList.add(truststoreFile);
+            Truststore truststore = truststoreFileFactory.create(truststorePath, passwordPath);
+            truststoreFilesList.add(truststore);
         }
 
         return truststoreFilesList;
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/TruststoreFileWithPassword.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/AliasConflictException.java
index 484f2d4f..a4102d9f 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/TruststoreFileWithPassword.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/AliasConflictException.java
@@ -17,19 +17,15 @@
  * ============LICENSE_END=========================================================
  */
 
-package org.onap.oom.truststoremerger.certification.file;
+package org.onap.oom.truststoremerger.certification.file.exception;
 
-import java.io.File;
+import org.onap.oom.truststoremerger.api.ExitStatus;
+import org.onap.oom.truststoremerger.api.ExitableException;
 
-public abstract class TruststoreFileWithPassword extends TruststoreFile {
-    private String password;
+public class AliasConflictException extends ExitableException {
 
-    TruststoreFileWithPassword(File truststoreFile, String password) {
-        super(truststoreFile);
-        this.password = password;
+    public AliasConflictException(String message) {
+        super(message, ExitStatus.ALIAS_CONFLICT_EXCEPTION);
     }
 
-    public String getPassword(){
-        return password;
-    };
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/CreateBackupException.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/CreateBackupException.java
new file mode 100644
index 00000000..a21f7013
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/CreateBackupException.java
@@ -0,0 +1,30 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.exception;
+
+import org.onap.oom.truststoremerger.api.ExitStatus;
+import org.onap.oom.truststoremerger.api.ExitableException;
+
+public class CreateBackupException extends ExitableException {
+
+    public CreateBackupException(Exception e) {
+        super(e, ExitStatus.CREATE_BACKUP_EXCEPTION);
+    }
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/KeystoreInstanceException.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/KeystoreInstanceException.java
new file mode 100644
index 00000000..c5bcc3ca
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/KeystoreInstanceException.java
@@ -0,0 +1,30 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.exception;
+
+import org.onap.oom.truststoremerger.api.ExitStatus;
+import org.onap.oom.truststoremerger.api.ExitableException;
+
+public class KeystoreInstanceException extends ExitableException {
+
+    public KeystoreInstanceException(Throwable e) {
+        super(e, ExitStatus.KEYSTORE_INSTANCE_EXCEPTION);
+    }
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/PemTruststore.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/LoadTruststoreException.java
index ca2ac85d..b8bb53fa 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/PemTruststore.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/LoadTruststoreException.java
@@ -17,21 +17,14 @@
  * ============LICENSE_END=========================================================
  */
 
-package org.onap.oom.truststoremerger.certification.file;
+package org.onap.oom.truststoremerger.certification.file.exception;
 
-import java.io.File;
-import java.security.cert.Certificate;
-import java.util.Collections;
-import java.util.List;
+import org.onap.oom.truststoremerger.api.ExitStatus;
+import org.onap.oom.truststoremerger.api.ExitableException;
 
-public class PemTruststore extends TruststoreFile {
+public class LoadTruststoreException extends ExitableException {
 
-    public PemTruststore(File truststoreFile) {
-        super(truststoreFile);
-    }
-
-    @Override
-    public List<Certificate> getCertificates() {
-        return Collections.emptyList();
+    public LoadTruststoreException(Throwable e) {
+        super(e, ExitStatus.TRUSTSTORE_LOAD_FILE_EXCEPTION);
     }
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/TruststoreFile.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/MissingTruststoreException.java
index 88b1b5a8..c502d6b6 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/TruststoreFile.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/MissingTruststoreException.java
@@ -17,22 +17,14 @@
  * ============LICENSE_END=========================================================
  */
 
-package org.onap.oom.truststoremerger.certification.file;
+package org.onap.oom.truststoremerger.certification.file.exception;
 
-import java.io.File;
-import java.security.cert.Certificate;
-import java.util.List;
+import org.onap.oom.truststoremerger.api.ExitStatus;
+import org.onap.oom.truststoremerger.api.ExitableException;
 
-public abstract class TruststoreFile {
-    private File truststoreFile;
+public class MissingTruststoreException extends ExitableException {
 
-    TruststoreFile(File truststoreFile) {
-        this.truststoreFile = truststoreFile;
+    public MissingTruststoreException(String message) {
+        super(message, ExitStatus.MISSING_TRUSTSTORE_EXCEPTION);
     }
-
-    public abstract List<Certificate> getCertificates();
-
-    public File getTruststoreFile() {
-        return truststoreFile;
-    };
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReaderException.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/PasswordReaderException.java
index 2928f0c5..d601d229 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReaderException.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/PasswordReaderException.java
@@ -17,13 +17,13 @@
  * ============LICENSE_END=========================================================
  */
 
-package org.onap.oom.truststoremerger.certification.file.provider;
+package org.onap.oom.truststoremerger.certification.file.exception;
 
 import org.onap.oom.truststoremerger.api.ExitStatus;
 import org.onap.oom.truststoremerger.api.ExitableException;
 
-class PasswordReaderException extends ExitableException {
-    PasswordReaderException(String message) {
+public class PasswordReaderException extends ExitableException {
+    public PasswordReaderException(String message) {
         super(message, ExitStatus.PASSWORD_READER_EXCEPTION);
     }
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/TruststoreDataOperationException.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/TruststoreDataOperationException.java
new file mode 100644
index 00000000..cf848f79
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/TruststoreDataOperationException.java
@@ -0,0 +1,30 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.exception;
+
+import org.onap.oom.truststoremerger.api.ExitStatus;
+import org.onap.oom.truststoremerger.api.ExitableException;
+
+public class TruststoreDataOperationException extends ExitableException {
+
+    public TruststoreDataOperationException(Exception e) {
+        super(e, ExitStatus.TRUSTSTORE_DATA_OPERATION_EXCEPTION);
+    }
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFileFactoryException.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/TruststoreFileFactoryException.java
index 43342c83..18349fd4 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFileFactoryException.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/TruststoreFileFactoryException.java
@@ -17,13 +17,13 @@
  * ============LICENSE_END=========================================================
  */
 
-package org.onap.oom.truststoremerger.certification.file.provider;
+package org.onap.oom.truststoremerger.certification.file.exception;
 
 import org.onap.oom.truststoremerger.api.ExitStatus;
 import org.onap.oom.truststoremerger.api.ExitableException;
 
-class TruststoreFileFactoryException extends ExitableException {
-    TruststoreFileFactoryException(String message) {
+public class TruststoreFileFactoryException extends ExitableException {
+    public TruststoreFileFactoryException(String message) {
         super(message, ExitStatus.TRUSTSTORE_FILE_FACTORY_EXCEPTION);
     }
 
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/WriteTruststoreFileException.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/WriteTruststoreFileException.java
new file mode 100644
index 00000000..a5e02b3c
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/exception/WriteTruststoreFileException.java
@@ -0,0 +1,31 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+
+package org.onap.oom.truststoremerger.certification.file.exception;
+
+import org.onap.oom.truststoremerger.api.ExitStatus;
+import org.onap.oom.truststoremerger.api.ExitableException;
+
+public class WriteTruststoreFileException extends ExitableException {
+
+    public WriteTruststoreFileException(Exception e) {
+        super(e, ExitStatus.WRITE_TRUSTSTORE_FILE_EXCEPTION);
+    }
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/model/JavaTruststore.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/model/JavaTruststore.java
new file mode 100644
index 00000000..d46fba1e
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/model/JavaTruststore.java
@@ -0,0 +1,58 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.model;
+
+import java.io.File;
+import java.util.List;
+import org.onap.oom.truststoremerger.api.ExitableException;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.exception.WriteTruststoreFileException;
+import org.onap.oom.truststoremerger.certification.file.provider.JavaCertificateStoreController;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class JavaTruststore extends Truststore {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(JavaTruststore.class);
+    private final JavaCertificateStoreController storeController;
+
+    public JavaTruststore(File truststoreFile, JavaCertificateStoreController storeController) {
+        super(truststoreFile);
+        this.storeController = storeController;
+    }
+
+    @Override
+    public List<CertificateWithAlias> getCertificates() throws ExitableException {
+        LOGGER.debug("Attempt ro read certificates from file: {} ", this.getFile().getPath());
+        return storeController.getNotEmptyCertificateList();
+    }
+
+    @Override
+    public void addCertificate(List<CertificateWithAlias> certificates) throws ExitableException {
+        LOGGER.debug("Attempt to add certificates for saving to file");
+        storeController.addCertificates(certificates);
+    }
+
+    @Override
+    public void saveFile() throws WriteTruststoreFileException {
+        LOGGER.debug("Attempt to save file: {}", this.getFile().getPath());
+        storeController.saveFile();
+    }
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/model/PemTruststore.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/model/PemTruststore.java
new file mode 100644
index 00000000..36195267
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/model/PemTruststore.java
@@ -0,0 +1,58 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.model;
+
+import java.io.File;
+import java.util.List;
+import org.onap.oom.truststoremerger.api.ExitableException;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.provider.PemCertificateController;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class PemTruststore extends Truststore {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(PemTruststore.class);
+    private final PemCertificateController pemCertificateController;
+
+    public PemTruststore(File truststoreFile, PemCertificateController pemCertificateController) {
+        super(truststoreFile);
+        this.pemCertificateController = pemCertificateController;
+    }
+
+    @Override
+    public List<CertificateWithAlias> getCertificates() throws ExitableException {
+        LOGGER.debug("Attempt ro read certificates from file: {}", this.getFile().getPath());
+        return pemCertificateController.getNotEmptyCertificateList();
+    }
+
+    @Override
+    public void addCertificate(List<CertificateWithAlias> certificates) throws ExitableException {
+        LOGGER.debug("Attempt to add certificates for saving to file");
+        pemCertificateController.addCertificates(certificates);
+    }
+
+    @Override
+    public void saveFile() throws ExitableException {
+        LOGGER.debug("Attempt to save file: {}", this.getFile().getPath());
+        pemCertificateController.saveFile();
+    }
+
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/model/Truststore.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/model/Truststore.java
new file mode 100644
index 00000000..153805a7
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/model/Truststore.java
@@ -0,0 +1,62 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.model;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.nio.file.Files;
+import java.util.List;
+import org.onap.oom.truststoremerger.api.ExitableException;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.exception.CreateBackupException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public abstract class Truststore {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(Truststore.class);
+    private static final String BACKUP_EXTENSION = ".bak";
+    private final File file;
+
+    Truststore(File file) {
+        this.file = file;
+    }
+
+    public abstract List<CertificateWithAlias> getCertificates() throws ExitableException;
+
+    public abstract void addCertificate(List<CertificateWithAlias> certificates) throws ExitableException;
+
+    public abstract void saveFile() throws ExitableException;
+
+    public File getFile() {
+        return file;
+    }
+
+    public void createBackup() throws CreateBackupException {
+        LOGGER.debug("Create backup of file: {}", file.getPath());
+        String backupFilePath = file.getAbsolutePath() + BACKUP_EXTENSION;
+        try (FileOutputStream fileOutputStream = new FileOutputStream(backupFilePath)) {
+            Files.copy(file.toPath(), fileOutputStream);
+        } catch (Exception e) {
+            LOGGER.error("Cannot create backup of file: {} ", getFile().getPath());
+            throw new CreateBackupException(e);
+        }
+    }
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/CertificateController.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/CertificateController.java
new file mode 100644
index 00000000..f2ed2c45
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/CertificateController.java
@@ -0,0 +1,33 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.provider;
+
+import java.util.List;
+import org.onap.oom.truststoremerger.api.ExitableException;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+
+public interface CertificateController {
+
+    List<CertificateWithAlias> getNotEmptyCertificateList() throws ExitableException;
+
+    void addCertificates(List<CertificateWithAlias> certificates) throws ExitableException;
+
+    void saveFile() throws ExitableException;
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/CertificateStoreControllerFactory.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/CertificateStoreControllerFactory.java
new file mode 100644
index 00000000..66e2aed2
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/CertificateStoreControllerFactory.java
@@ -0,0 +1,61 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.provider;
+
+import static org.onap.oom.truststoremerger.api.CertificateConstants.JKS_INSTANCE;
+import static org.onap.oom.truststoremerger.api.CertificateConstants.PKCS12_INSTANCE;
+
+import java.io.File;
+import java.security.KeyStore;
+import java.security.KeyStoreException;
+import org.onap.oom.truststoremerger.certification.file.exception.KeystoreInstanceException;
+import org.onap.oom.truststoremerger.certification.file.exception.LoadTruststoreException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class CertificateStoreControllerFactory {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(CertificateStoreControllerFactory.class);
+
+    public JavaCertificateStoreController createLoadedJksCertificateStoreController(File certFile, String certPassword)
+        throws LoadTruststoreException, KeystoreInstanceException {
+        return createLoadedCertificateStoreController(certFile, certPassword, JKS_INSTANCE);
+    }
+
+    public JavaCertificateStoreController createLoadedPkcs12CertificateStoreController(File certFile, String certPassword)
+        throws KeystoreInstanceException, LoadTruststoreException {
+        return createLoadedCertificateStoreController(certFile, certPassword, PKCS12_INSTANCE);
+    }
+
+    private JavaCertificateStoreController createLoadedCertificateStoreController(File certFile, String certPassword,
+        String instanceType)
+        throws LoadTruststoreException, KeystoreInstanceException {
+        try {
+            JavaCertificateStoreController javaCertificateStoreController = new JavaCertificateStoreController(
+                KeyStore.getInstance(instanceType), certFile, certPassword);
+            javaCertificateStoreController.loadFile();
+            return javaCertificateStoreController;
+        } catch (KeyStoreException e) {
+            LOGGER.error("Cannot initialize Java Keystore instance");
+            throw new KeystoreInstanceException(e);
+        }
+    }
+}
+
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/FileManager.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/FileManager.java
index 901c13ab..12029ade 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/FileManager.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/FileManager.java
@@ -22,17 +22,18 @@ package org.onap.oom.truststoremerger.certification.file.provider;
 import java.io.File;
 
 public class FileManager {
-    private static final int NOT_FOUND_INDEX=-1;
 
-    String getExtension(File file) {
+    private static final int INDEX_NOT_FOUND = -1;
+
+    public String getExtension(File file) {
         int extStartIndex = file.getName().lastIndexOf(".");
-        if (extStartIndex == NOT_FOUND_INDEX) {
+        if (extStartIndex == INDEX_NOT_FOUND) {
             return "";
         }
-        return file.getName().substring(extStartIndex);
+        return file.getName().substring(extStartIndex).toLowerCase();
     }
 
-    boolean checkIfFileExists(File file){
+    public boolean checkIfFileExists(File file) {
         return file.exists();
     }
 
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/JavaCertificateStoreController.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/JavaCertificateStoreController.java
new file mode 100644
index 00000000..1c20fd38
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/JavaCertificateStoreController.java
@@ -0,0 +1,156 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.provider;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.security.KeyStore;
+import java.security.KeyStoreException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import org.onap.oom.truststoremerger.api.ExitableException;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAliasFactory;
+import org.onap.oom.truststoremerger.certification.file.exception.AliasConflictException;
+import org.onap.oom.truststoremerger.certification.file.exception.TruststoreDataOperationException;
+import org.onap.oom.truststoremerger.certification.file.exception.LoadTruststoreException;
+import org.onap.oom.truststoremerger.certification.file.exception.MissingTruststoreException;
+import org.onap.oom.truststoremerger.certification.file.exception.WriteTruststoreFileException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class JavaCertificateStoreController implements CertificateController {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(JavaCertificateStoreController.class);
+
+    private final CertificateWithAliasFactory factory = new CertificateWithAliasFactory();
+    private final KeyStore keyStore;
+    private final File storeFile;
+    private final String password;
+
+
+    public JavaCertificateStoreController(KeyStore keyStore, File storeFile, String password) {
+        this.keyStore = keyStore;
+        this.storeFile = storeFile;
+        this.password = password;
+    }
+
+    public List<CertificateWithAlias> getNotEmptyCertificateList() throws ExitableException {
+        List<String> aliases = getTruststoreAliasesList();
+        if (aliases.isEmpty()) {
+            throw new MissingTruststoreException("Missing certificate aliases in file: " + storeFile.getPath());
+        }
+        return getWrappedCertificates(aliases);
+    }
+
+    public void addCertificates(List<CertificateWithAlias> certificatesWithAliases)
+        throws ExitableException {
+        if (getTruststoreAliasesList().isEmpty()){
+            throw new MissingTruststoreException("Missing certificate aliases in file: " + storeFile.getPath());
+        }
+        for (CertificateWithAlias certificate : certificatesWithAliases) {
+            addCertificate(certificate);
+        }
+    }
+
+    public void saveFile() throws WriteTruststoreFileException {
+        try (FileOutputStream outputStream = new FileOutputStream(this.storeFile)) {
+            keyStore.store(outputStream, this.password.toCharArray());
+        } catch (Exception e) {
+            LOGGER.error("Cannot write truststore file");
+            throw new WriteTruststoreFileException(e);
+        }
+    }
+
+    public void loadFile() throws LoadTruststoreException {
+        try {
+            keyStore.load(new FileInputStream(this.storeFile), this.password.toCharArray());
+        } catch (Exception e) {
+            LOGGER.error("Cannot load file: {}", this.storeFile.getPath());
+            throw new LoadTruststoreException(e);
+        }
+    }
+
+    private void addCertificate(CertificateWithAlias certificate)
+        throws TruststoreDataOperationException, AliasConflictException {
+        if (hasAliasConflict(certificate)) {
+            LOGGER.error("Alias conflict detected");
+            throw new AliasConflictException("Alias conflict detected. Alias conflicted: " + certificate.getAlias());
+        }
+        try {
+            keyStore.setCertificateEntry(certificate.getAlias(), certificate.getCertificate());
+        } catch (KeyStoreException e) {
+            LOGGER.error("Cannot merge certificate with alias: {}", certificate.getAlias());
+            throw new TruststoreDataOperationException(e);
+        }
+    }
+
+    private boolean hasAliasConflict(CertificateWithAlias certificate) throws TruststoreDataOperationException {
+        try {
+            return keyStore.containsAlias(certificate.getAlias());
+        } catch (KeyStoreException e) {
+            LOGGER.error("Cannot check alias conflict");
+            throw new TruststoreDataOperationException(e);
+        }
+    }
+
+    private List<CertificateWithAlias> getWrappedCertificates(List<String> aliases)
+        throws TruststoreDataOperationException {
+
+        List<CertificateWithAlias> certificateWrapped = new ArrayList<>();
+
+        for (String alias : aliases) {
+            certificateWrapped.add(createWrappedCertificate(alias));
+        }
+        return certificateWrapped;
+    }
+
+    private CertificateWithAlias createWrappedCertificate(String alias) throws TruststoreDataOperationException {
+        try {
+            return factory.createCertificateWithAlias(keyStore.getCertificate(alias), alias);
+        } catch (KeyStoreException e) {
+            LOGGER.warn("Cannot get certificate with alias: {} ", alias);
+            throw new TruststoreDataOperationException(e);
+        }
+    }
+
+    private List<String> getTruststoreAliasesList() throws TruststoreDataOperationException {
+        try {
+            List<String> aliases = Collections.list(keyStore.aliases());
+            return getFilteredAlias(aliases);
+        } catch (KeyStoreException e) {
+            LOGGER.warn("Cannot read truststore aliases");
+            throw new TruststoreDataOperationException(e);
+        }
+    }
+
+    private List<String> getFilteredAlias(List<String> aliases) throws KeyStoreException {
+        List<String> filteredAlias = new ArrayList<>();
+        for (String alias : aliases) {
+            if (keyStore.isCertificateEntry(alias)) {
+                filteredAlias.add(alias);
+            }
+        }
+        return filteredAlias;
+    }
+
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReader.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReader.java
index db42f3bd..d7da53b0 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReader.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReader.java
@@ -22,11 +22,12 @@ package org.onap.oom.truststoremerger.certification.file.provider;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
+import org.onap.oom.truststoremerger.certification.file.exception.PasswordReaderException;
 
 public class PasswordReader {
     private static final String COULD_NOT_READ_PASSWORD_FROM_FILE_MSG_TEMPLATE = "Could not read password from file: %s";
 
-    String readPassword(File file) throws PasswordReaderException {
+    public String readPassword(File file) throws PasswordReaderException {
         try {
             return Files.readString(file.toPath());
         } catch (IOException e) {
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/PemCertificateController.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/PemCertificateController.java
new file mode 100644
index 00000000..9ff42b87
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/PemCertificateController.java
@@ -0,0 +1,155 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.provider;
+
+import static org.onap.oom.truststoremerger.api.CertificateConstants.BOUNCY_CASTLE_PROVIDER;
+import static org.onap.oom.truststoremerger.api.CertificateConstants.X_509_CERTIFICATE;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.StringWriter;
+import java.security.Security;
+import java.security.cert.Certificate;
+import java.security.cert.CertificateFactory;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import org.bouncycastle.openssl.jcajce.JcaMiscPEMGenerator;
+import org.bouncycastle.util.io.pem.PemObjectGenerator;
+import org.bouncycastle.util.io.pem.PemWriter;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAliasFactory;
+import org.onap.oom.truststoremerger.certification.file.exception.MissingTruststoreException;
+import org.onap.oom.truststoremerger.certification.file.exception.TruststoreDataOperationException;
+import org.onap.oom.truststoremerger.certification.file.exception.WriteTruststoreFileException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class PemCertificateController implements CertificateController {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(PemCertificateController.class);
+
+    private static final boolean APPEND_TO_FILE = true;
+
+    private final CertificateWithAliasFactory factory = new CertificateWithAliasFactory();
+    private final List<CertificateWithAlias> certificatesToBeSaved = new ArrayList<>();
+    private final File file;
+
+    public PemCertificateController(File file) {
+        this.file = file;
+    }
+
+    public List<CertificateWithAlias> getNotEmptyCertificateList()
+        throws TruststoreDataOperationException, MissingTruststoreException {
+        if (isFileWithoutPemCertificate()) {
+            throw new MissingTruststoreException("File does not contain any certificate");
+        }
+        List<Certificate> extractedCertificate = extractCertificatesFromFile();
+        return wrapCertificates(extractedCertificate);
+    }
+
+    public void addCertificates(List<CertificateWithAlias> certificates)
+        throws TruststoreDataOperationException, MissingTruststoreException {
+        if (isFileWithoutPemCertificate()) {
+            LOGGER.error("File does not contain any certificate. File path: {} ", this.file.getPath());
+            throw new MissingTruststoreException("File does not contain any certificate");
+        }
+        certificatesToBeSaved.addAll(certificates);
+    }
+
+    public void saveFile() throws WriteTruststoreFileException, TruststoreDataOperationException {
+        List<Certificate> certificates = certificatesToBeSaved.stream()
+            .map(CertificateWithAlias::getCertificate)
+            .collect(Collectors.toList());
+        String certificatesAsString = transformToStringInPemFormat(certificates);
+        appendToFile(certificatesAsString);
+    }
+
+    boolean isFileWithoutPemCertificate() throws TruststoreDataOperationException {
+        List<Certificate> certificateList = extractCertificatesFromFile();
+        return certificateList.isEmpty();
+    }
+
+    String transformToStringInPemFormat(List<Certificate> certificates) throws TruststoreDataOperationException {
+        StringWriter sw = new StringWriter();
+        List<PemObjectGenerator> generators = transformToPemGenerators(certificates);
+        try (PemWriter pemWriter = new PemWriter(sw)) {
+            for (PemObjectGenerator generator : generators) {
+                pemWriter.writeObject(generator);
+            }
+        } catch (IOException e) {
+            LOGGER.error("Cannot convert certificates to PEM format");
+            throw new TruststoreDataOperationException(e);
+        }
+        return sw.toString();
+    }
+
+
+    private List<Certificate> extractCertificatesFromFile() throws TruststoreDataOperationException {
+        try (FileInputStream inputStream = new FileInputStream(this.file)) {
+            Security.addProvider(new BouncyCastleProvider());
+            CertificateFactory factory = CertificateFactory.getInstance(X_509_CERTIFICATE, BOUNCY_CASTLE_PROVIDER);
+            return new ArrayList<>(factory.generateCertificates(inputStream));
+        } catch (Exception e) {
+            LOGGER.error("Cannot read certificates from file: {}", this.file.getPath());
+            throw new TruststoreDataOperationException(e);
+        }
+    }
+
+
+    private List<PemObjectGenerator> transformToPemGenerators(List<Certificate> certificates)
+        throws TruststoreDataOperationException {
+        List<PemObjectGenerator> generators = new ArrayList<>();
+        for (Certificate certificate : certificates) {
+            PemObjectGenerator generator = createPemGenerator(certificate);
+            generators.add(generator);
+        }
+        return generators;
+    }
+
+    private JcaMiscPEMGenerator createPemGenerator(Certificate certificate)
+        throws TruststoreDataOperationException {
+        try {
+            return new JcaMiscPEMGenerator(certificate);
+        } catch (IOException e) {
+            LOGGER.error("Cannot convert Certificate Object to PemGenerator Object");
+            throw new TruststoreDataOperationException(e);
+        }
+    }
+
+    private List<CertificateWithAlias> wrapCertificates(List<Certificate> rawCertificates) {
+        return rawCertificates.stream()
+            .map(factory::createPemCertificate)
+            .collect(Collectors.toList());
+    }
+
+    private void appendToFile(String certificatesAsString) throws WriteTruststoreFileException {
+        try {
+            FileOutputStream fileOutputStream = new FileOutputStream(this.file, APPEND_TO_FILE);
+            fileOutputStream.write(certificatesAsString.getBytes());
+        } catch (Exception e) {
+            LOGGER.error("Cannot write certificates to file");
+            throw new WriteTruststoreFileException(e);
+        }
+    }
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFileFactory.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFileFactory.java
deleted file mode 100644
index e63e7c33..00000000
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFileFactory.java
+++ /dev/null
@@ -1,84 +0,0 @@
-/*============LICENSE_START=======================================================
- * oom-truststore-merger
- * ================================================================================
- * Copyright (C) 2020 Nokia. All rights reserved.
- * ================================================================================
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- * ============LICENSE_END=========================================================
- */
-
-package org.onap.oom.truststoremerger.certification.file.provider;
-
-import org.onap.oom.truststoremerger.certification.file.JksTruststore;
-import org.onap.oom.truststoremerger.certification.file.P12Truststore;
-import org.onap.oom.truststoremerger.certification.file.PemTruststore;
-import org.onap.oom.truststoremerger.certification.file.TruststoreFile;
-
-import java.io.File;
-
-public class TruststoreFileFactory {
-
-    private static final String JKS_EXTENSION = ".jks";
-    private static final String P12_EXTENSION = ".p12";
-    private static final String PEM_EXTENSION = ".pem";
-    private static final String FILE_DOES_NOT_EXIST_MSG_TEMPLATE = "File: %s does not exist";
-    private static final String UNKNOWN_TRUSTSTORE_TYPE_MSG_TEMPLATE = "Unknown truststore extension type: %s";
-
-    private final FileManager fileManager;
-    private final PasswordReader passwordReader;
-
-    public TruststoreFileFactory(FileManager fileManager, PasswordReader passwordReader) {
-        this.fileManager = fileManager;
-        this.passwordReader = passwordReader;
-    }
-
-    TruststoreFile create(String truststoreFilePath, String truststorePasswordPath)
-            throws TruststoreFileFactoryException, PasswordReaderException {
-        File truststoreFile = new File(truststoreFilePath);
-        if (!fileManager.checkIfFileExists(truststoreFile)) {
-            throw new TruststoreFileFactoryException(String.format(FILE_DOES_NOT_EXIST_MSG_TEMPLATE, truststoreFile));
-        }
-        return createTypedTruststore(truststoreFile, truststorePasswordPath);
-    }
-
-    private TruststoreFile createTypedTruststore(File truststoreFile, String truststorePasswordPath)
-            throws PasswordReaderException, TruststoreFileFactoryException {
-        String extension = fileManager.getExtension(truststoreFile);
-        switch (extension) {
-            case JKS_EXTENSION:
-                return createJksTruststore(truststoreFile, truststorePasswordPath);
-            case P12_EXTENSION:
-                return createP12Truststore(truststoreFile, truststorePasswordPath);
-            case PEM_EXTENSION:
-                return createPemTruststore(truststoreFile);
-            default:
-                throw new TruststoreFileFactoryException(String.format(UNKNOWN_TRUSTSTORE_TYPE_MSG_TEMPLATE, extension));
-        }
-    }
-
-    private JksTruststore createJksTruststore(File truststoreFile, String truststorePasswordPath)
-            throws PasswordReaderException {
-        String password = passwordReader.readPassword(new File(truststorePasswordPath));
-        return new JksTruststore(truststoreFile, password);
-    }
-
-    private P12Truststore createP12Truststore(File truststoreFile, String truststorePasswordPath)
-            throws PasswordReaderException {
-        String password = passwordReader.readPassword(new File(truststorePasswordPath));
-        return new P12Truststore(truststoreFile, password);
-    }
-
-    private PemTruststore createPemTruststore(File truststoreFile) {
-        return new PemTruststore(truststoreFile);
-    }
-}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/P12Truststore.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/entry/CertificateWithAlias.java
index 8527cce5..decc3977 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/P12Truststore.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/entry/CertificateWithAlias.java
@@ -17,22 +17,25 @@
  * ============LICENSE_END=========================================================
  */
 
-package org.onap.oom.truststoremerger.certification.file;
+package org.onap.oom.truststoremerger.certification.file.provider.entry;
 
-import java.io.File;
 import java.security.cert.Certificate;
-import java.util.Collections;
-import java.util.List;
 
-public class P12Truststore extends TruststoreFileWithPassword {
+public class CertificateWithAlias {
 
-    public P12Truststore(File truststoreFile, String password) {
-        super(truststoreFile, password);
+    private final Certificate certificate;
+    private final String alias;
+
+    public CertificateWithAlias(Certificate certificate, String alias) {
+        this.certificate = certificate;
+        this.alias = alias;
     }
 
-    @Override
-    public List<Certificate> getCertificates() {
-        return Collections.emptyList();
+    public String getAlias() {
+        return this.alias;
     }
 
+    public Certificate getCertificate() {
+        return this.certificate;
+    }
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/JksTruststore.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/entry/CertificateWithAliasFactory.java
index b977daee..0889650e 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/JksTruststore.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/entry/CertificateWithAliasFactory.java
@@ -17,21 +17,17 @@
  * ============LICENSE_END=========================================================
  */
 
-package org.onap.oom.truststoremerger.certification.file;
+package org.onap.oom.truststoremerger.certification.file.provider.entry;
 
-import java.io.File;
 import java.security.cert.Certificate;
-import java.util.Collections;
-import java.util.List;
 
-public class JksTruststore extends TruststoreFileWithPassword {
+public class CertificateWithAliasFactory {
 
-    public JksTruststore(File truststoreFile, String password) {
-        super(truststoreFile, password);
+    public CertificateWithAlias createCertificateWithAlias(Certificate certificate, String alias) {
+        return new CertificateWithAlias(certificate, alias);
     }
 
-    @Override
-    public List<Certificate> getCertificates() {
-        return Collections.emptyList();
+    public CertificateWithAlias createPemCertificate(Certificate certificate) {
+        return new CertificateWithAlias(certificate, PemAliasGenerator.getInstance().getAlias());
     }
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/entry/PemAliasGenerator.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/entry/PemAliasGenerator.java
new file mode 100644
index 00000000..56faa1f6
--- /dev/null
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/file/provider/entry/PemAliasGenerator.java
@@ -0,0 +1,42 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.provider.entry;
+
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class PemAliasGenerator {
+
+    private static final String PREFIX_ALIAS_NAME = "pem-trusted-certificate-";
+    private static final PemAliasGenerator INSTANCE = new PemAliasGenerator();
+    private static AtomicInteger counter = new AtomicInteger(0);
+
+    private PemAliasGenerator() {
+    }
+
+    public static PemAliasGenerator getInstance() {
+        return INSTANCE;
+    }
+
+    public String getAlias() {
+
+        return PREFIX_ALIAS_NAME + counter.getAndIncrement();
+    }
+}
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/path/EnvProvider.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/path/EnvProvider.java
index 4bb763da..a1998b86 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/path/EnvProvider.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/path/EnvProvider.java
@@ -21,9 +21,16 @@ package org.onap.oom.truststoremerger.certification.path;
 
 import java.util.Optional;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 public class EnvProvider {
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(EnvProvider.class);
+
     Optional<String> getEnv(String name) {
+        String value = System.getenv(name);
+        LOGGER.info("Read variable: {} , value: {}", name, value);
         return Optional.ofNullable(System.getenv(name));
     }
 }
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/path/TruststoresPathsProvider.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/path/TruststoresPathsProvider.java
index f8e85d49..9d86a8b9 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/path/TruststoresPathsProvider.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/certification/path/TruststoresPathsProvider.java
@@ -19,8 +19,8 @@
 
 package org.onap.oom.truststoremerger.certification.path;
 
-import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_ENV;
-import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_PASSWORDS_ENV;
+import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_PATHS_ENV;
+import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_PASSWORDS_PATHS_ENV;
 
 import java.util.Arrays;
 import java.util.List;
@@ -31,8 +31,8 @@ public class TruststoresPathsProvider {
     private static final String DELIMITER = ":";
     private static final int NEGATIVE_SPLIT_LIMIT = -1;
 
-    private EnvProvider envProvider;
-    private PathValidator pathValidator;
+    private final EnvProvider envProvider;
+    private final PathValidator pathValidator;
 
     public TruststoresPathsProvider(EnvProvider envProvider, PathValidator pathValidator) {
         this.envProvider = envProvider;
@@ -40,20 +40,20 @@ public class TruststoresPathsProvider {
     }
 
     public List<String> getTruststores() throws TruststoresPathsProviderException {
-        return envProvider.getEnv(TRUSTSTORES_ENV)
+        return envProvider.getEnv(TRUSTSTORES_PATHS_ENV)
             .filter(Predicate.not(String::isEmpty))
             .map(this::splitToList)
             .filter(this::validateTruststores)
             .orElseThrow(() -> new TruststoresPathsProviderException(
-                TRUSTSTORES_ENV + " environment variable does not contain valid truststores paths"));
+                TRUSTSTORES_PATHS_ENV + " environment variable does not contain valid truststores paths"));
     }
 
     public List<String> getTruststoresPasswords() throws TruststoresPathsProviderException {
-        return envProvider.getEnv(TRUSTSTORES_PASSWORDS_ENV)
+        return envProvider.getEnv(TRUSTSTORES_PASSWORDS_PATHS_ENV)
             .map(this::splitToList)
             .filter(this::validateTruststoresPasswords)
             .orElseThrow(() -> new TruststoresPathsProviderException(
-                TRUSTSTORES_PASSWORDS_ENV + " environment variable does not contain valid passwords paths"));
+                TRUSTSTORES_PASSWORDS_PATHS_ENV + " environment variable does not contain valid passwords paths"));
     }
 
     private boolean validateTruststores(List<String> truststores) {
diff --git a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/configuration/MergerConfigurationFactory.java b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/configuration/MergerConfigurationFactory.java
index 7a2fdc10..acd9a840 100644
--- a/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/configuration/MergerConfigurationFactory.java
+++ b/trustStoreMerger/src/main/java/org/onap/oom/truststoremerger/configuration/MergerConfigurationFactory.java
@@ -22,8 +22,8 @@ package org.onap.oom.truststoremerger.configuration;
 import org.onap.oom.truststoremerger.certification.path.TruststoresPathsProvider;
 import org.onap.oom.truststoremerger.certification.path.TruststoresPathsProviderException;
 
-import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_ENV;
-import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_PASSWORDS_ENV;
+import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_PATHS_ENV;
+import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_PASSWORDS_PATHS_ENV;
 
 import java.util.List;
 
@@ -42,8 +42,8 @@ public class MergerConfigurationFactory {
 
         if (truststores.size() != truststoresPasswords.size()) {
             throw new MergerConfigurationException(
-                "Size of " + TRUSTSTORES_ENV
-                    + " does not match size of " + TRUSTSTORES_PASSWORDS_ENV + " environment variables");
+                "Size of " + TRUSTSTORES_PATHS_ENV
+                    + " does not match size of " + TRUSTSTORES_PASSWORDS_PATHS_ENV + " environment variables");
         }
 
         return new MergerConfiguration(truststores, truststoresPasswords);
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/TestCertificateProvider.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/TestCertificateProvider.java
new file mode 100644
index 00000000..c971ca17
--- /dev/null
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/TestCertificateProvider.java
@@ -0,0 +1,157 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardCopyOption;
+import org.onap.oom.truststoremerger.certification.file.exception.KeystoreInstanceException;
+import org.onap.oom.truststoremerger.certification.file.exception.LoadTruststoreException;
+import org.onap.oom.truststoremerger.certification.file.model.JavaTruststore;
+import org.onap.oom.truststoremerger.certification.file.model.PemTruststore;
+import org.onap.oom.truststoremerger.certification.file.provider.JavaCertificateStoreController;
+import org.onap.oom.truststoremerger.certification.file.provider.CertificateStoreControllerFactory;
+import org.onap.oom.truststoremerger.certification.file.provider.PemCertificateController;
+
+public class TestCertificateProvider {
+
+    public static final String SAMPLE_P12_TRUSTSTORE_FILE_PATH = "src/test/resources/truststore-p12.p12";
+    public static final String SAMPLE_P12_TRUSTSTORE_PASSWORD = "88y9v5D8H3SG6bZWRVHDfOAo";
+    public static final String TMP_P12_TRUSTSTORE_FILE_PATH = "src/test/resources/tmp-truststore-p12.p12";
+
+    public static final String SAMPLE_P12_KEYSTORE_FILE_PATH = "src/test/resources/keystore.p12";
+    public static final String SAMPLE_P12_KEYSTORE_PASSWORD = "Foh49MJNYI7S_pEzE9gvUDSu";
+
+    public static final String SAMPLE_JKS_TRUSTSTORE_FILE_PATH = "src/test/resources/truststore-jks.jks";
+    public static final String SAMPLE_JKS_TRUSTSTORE_UNIQUE_ALIAS_FILE_PATH = "src/test/resources/truststore-jks-uniq.jks";
+    public static final String SAMPLE_JKS_TRUSTSTORE_PASSWORD = "EOyuFbuYDyq_EhpboM72RHua";
+    public static final String TMP_JKS_TRUSTSTORE_FILE_PATH = "src/test/resources/tmp-truststore-jks.jks";
+
+    public static final String SAMPLE_PEM_TRUSTSTORE_FILE_PATH = "src/test/resources/truststore.pem";
+    public static final String EMPTY_PEM_TRUSTSTORE_FILE_PATH = "src/test/resources/empty-truststore.pem";
+    public static final String TMP_PEM_TRUSTSTORE_FILE_PATH = "src/test/resources/tmp-truststore.pem";
+    public static final String SAMPLE_PEM_TRUSTSTORE_WITH_PRIVATE_KEY_FILE_PATH = "src/test/resources/truststore-with-private-key.pem";
+
+    private static final CertificateStoreControllerFactory certificateStoreControllerFactory = new CertificateStoreControllerFactory();
+
+    public static JavaTruststore getSampleP12Truststore() throws LoadTruststoreException, KeystoreInstanceException {
+        return createP12TruststoreInstance(SAMPLE_P12_TRUSTSTORE_FILE_PATH, SAMPLE_P12_TRUSTSTORE_PASSWORD);
+    }
+
+    public static JavaTruststore getSampleP12Keystore() throws LoadTruststoreException, KeystoreInstanceException {
+        return createP12TruststoreInstance(SAMPLE_P12_KEYSTORE_FILE_PATH, SAMPLE_P12_KEYSTORE_PASSWORD);
+    }
+
+    public static JavaTruststore createTmpP12TruststoreFile()
+        throws IOException, LoadTruststoreException, KeystoreInstanceException {
+        copyFile(SAMPLE_P12_TRUSTSTORE_FILE_PATH, TMP_P12_TRUSTSTORE_FILE_PATH);
+        return createP12TruststoreInstance(TMP_P12_TRUSTSTORE_FILE_PATH, SAMPLE_P12_TRUSTSTORE_PASSWORD);
+    }
+
+    public static JavaTruststore getTmpP12TruststoreFile() throws LoadTruststoreException, KeystoreInstanceException {
+        return createP12TruststoreInstance(TMP_P12_TRUSTSTORE_FILE_PATH, SAMPLE_P12_TRUSTSTORE_PASSWORD);
+    }
+
+    private static JavaTruststore createP12TruststoreInstance(String filePath, String password)
+        throws LoadTruststoreException, KeystoreInstanceException {
+        File certFile = getFile(filePath);
+        JavaCertificateStoreController storeController = certificateStoreControllerFactory
+            .createLoadedPkcs12CertificateStoreController(certFile, password);
+        return new JavaTruststore(certFile, storeController);
+    }
+
+    public static PemTruststore getSamplePemTruststoreFile() {
+        return getPemTruststoreInstance(SAMPLE_PEM_TRUSTSTORE_FILE_PATH);
+    }
+
+    public static PemTruststore getEmptyPemTruststoreFile() {
+        return getPemTruststoreInstance(EMPTY_PEM_TRUSTSTORE_FILE_PATH);
+    }
+
+    public static PemTruststore createEmptyTmpPemTruststoreFile() throws IOException {
+        copyFile(EMPTY_PEM_TRUSTSTORE_FILE_PATH, TMP_PEM_TRUSTSTORE_FILE_PATH);
+        return getPemTruststoreInstance(TMP_PEM_TRUSTSTORE_FILE_PATH);
+    }
+
+    public static PemTruststore createTmpPemTruststoreFile() throws IOException {
+        copyFile(SAMPLE_PEM_TRUSTSTORE_FILE_PATH, TMP_PEM_TRUSTSTORE_FILE_PATH);
+        return getPemTruststoreInstance(TMP_PEM_TRUSTSTORE_FILE_PATH);
+    }
+
+    public static PemTruststore getTmpPemTruststoreFile() {
+        return getPemTruststoreInstance(TMP_PEM_TRUSTSTORE_FILE_PATH);
+    }
+
+    public static PemTruststore getPemWithPrivateKeyTruststoreFile() {
+        return getPemTruststoreInstance(SAMPLE_PEM_TRUSTSTORE_WITH_PRIVATE_KEY_FILE_PATH);
+    }
+
+    public static String getExpectedPemCertificateAsString() throws IOException {
+        Path samplePemFilePath = Paths.get(SAMPLE_PEM_TRUSTSTORE_FILE_PATH);
+        return Files.readString(samplePemFilePath);
+    }
+
+    public static JavaTruststore getSampleJksTruststoreFile()
+        throws LoadTruststoreException, KeystoreInstanceException {
+        return createJKSTruststoreInstance(SAMPLE_JKS_TRUSTSTORE_FILE_PATH, SAMPLE_JKS_TRUSTSTORE_PASSWORD);
+    }
+
+    public static JavaTruststore getSampleJksTruststoreFileWithUniqueAlias()
+        throws LoadTruststoreException, KeystoreInstanceException {
+        return createJKSTruststoreInstance(SAMPLE_JKS_TRUSTSTORE_UNIQUE_ALIAS_FILE_PATH,
+            SAMPLE_JKS_TRUSTSTORE_PASSWORD);
+    }
+
+    public static JavaTruststore createTmpJksTruststoreFileWithUniqAlias()
+        throws IOException, LoadTruststoreException, KeystoreInstanceException {
+        copyFile(SAMPLE_JKS_TRUSTSTORE_UNIQUE_ALIAS_FILE_PATH, TMP_JKS_TRUSTSTORE_FILE_PATH);
+        return createJKSTruststoreInstance(TMP_JKS_TRUSTSTORE_FILE_PATH, SAMPLE_JKS_TRUSTSTORE_PASSWORD);
+    }
+
+    public static void removeTemporaryFiles() throws IOException {
+        Files.deleteIfExists(Paths.get(TMP_PEM_TRUSTSTORE_FILE_PATH));
+        Files.deleteIfExists(Paths.get(TMP_JKS_TRUSTSTORE_FILE_PATH));
+        Files.deleteIfExists(Paths.get(TMP_P12_TRUSTSTORE_FILE_PATH));
+    }
+
+    private static JavaTruststore createJKSTruststoreInstance(String filePath, String password)
+        throws LoadTruststoreException, KeystoreInstanceException {
+        File certFile = getFile(filePath);
+        JavaCertificateStoreController storeController = certificateStoreControllerFactory
+            .createLoadedJksCertificateStoreController(certFile, password);
+        return new JavaTruststore(certFile, storeController);
+    }
+
+    private static PemTruststore getPemTruststoreInstance(String tmpPemTruststoreFilePath) {
+        File file = getFile(tmpPemTruststoreFilePath);
+        return new PemTruststore(file, new PemCertificateController(file));
+    }
+
+    private static void copyFile(String sourcePath, String destPath) throws IOException {
+        Files.copy(Paths.get(sourcePath), Paths.get(destPath), StandardCopyOption.REPLACE_EXISTING);
+    }
+
+    private static File getFile(String path) {
+        return new File(path);
+    }
+}
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/model/JavaTruststoreTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/model/JavaTruststoreTest.java
new file mode 100644
index 00000000..eccf36bc
--- /dev/null
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/model/JavaTruststoreTest.java
@@ -0,0 +1,116 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.model;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.onap.oom.truststoremerger.api.CertificateConstants.X_509_CERTIFICATE;
+
+import java.io.IOException;
+import java.security.cert.Certificate;
+import java.util.List;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.Test;
+import org.onap.oom.truststoremerger.api.ExitableException;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.TestCertificateProvider;
+
+
+class JavaTruststoreTest {
+    public static final int FIRST_ELEMENT = 0;
+    private static final int EXPECTED_ONE = 1;
+    public static final int EXPECTED_THREE = 3;
+
+    @Test
+    void jksTruststoreShouldReadCertificatesFromFile() throws ExitableException {
+
+        //given
+        JavaTruststore jksTruststoreFile = TestCertificateProvider.getSampleJksTruststoreFile();
+
+        //when
+        List<CertificateWithAlias> certificates = jksTruststoreFile.getCertificates();
+        Certificate certificate = certificates.get(FIRST_ELEMENT).getCertificate();
+
+        //then
+        assertThat(certificates).hasSize(EXPECTED_ONE);
+        assertThat(certificate.getType()).isEqualTo(X_509_CERTIFICATE);
+    }
+
+    @Test
+    void jksTruststoreShouldAddDifferentCertificates() throws Exception {
+
+        //given
+        JavaTruststore jksTruststore = TestCertificateProvider.createTmpJksTruststoreFileWithUniqAlias();
+        List<CertificateWithAlias> p12certificates = TestCertificateProvider.getSampleP12Truststore()
+            .getCertificates();
+        List<CertificateWithAlias> pemCertificates = TestCertificateProvider.getSamplePemTruststoreFile()
+            .getCertificates();
+
+        //when
+        jksTruststore.addCertificate(p12certificates);
+        jksTruststore.addCertificate(pemCertificates);
+
+        //then
+        assertThat(jksTruststore.getCertificates()).hasSize(EXPECTED_THREE);
+
+    }
+
+    @Test
+    void p12TruststoreShouldReadCertificatesFromFile() throws ExitableException {
+        //given
+        JavaTruststore p12Truststore = TestCertificateProvider.getSampleP12Truststore();
+
+        //when
+        List<CertificateWithAlias> certificatesWithAliases = p12Truststore.getCertificates();
+        Certificate certificate = certificatesWithAliases.get(FIRST_ELEMENT).getCertificate();
+
+        //then
+        assertThat(certificatesWithAliases).hasSize(EXPECTED_ONE);
+        assertThat(certificate.getType()).isEqualTo(X_509_CERTIFICATE);
+    }
+
+
+    @Test
+    void p12TruststoreShouldAddDifferentCertificates() throws Exception {
+        //given
+        JavaTruststore p12Truststore = TestCertificateProvider.createTmpP12TruststoreFile();
+        List<CertificateWithAlias> jksTruststoreCertificates = TestCertificateProvider
+            .getSampleJksTruststoreFileWithUniqueAlias()
+            .getCertificates();
+        List<CertificateWithAlias> pemTruststoreCertificates = TestCertificateProvider.getSamplePemTruststoreFile()
+            .getCertificates();
+
+        //when
+        p12Truststore.addCertificate(jksTruststoreCertificates);
+        p12Truststore.addCertificate(pemTruststoreCertificates);
+        p12Truststore.saveFile();
+
+
+        //then
+        JavaTruststore p12TruststoreSaved = TestCertificateProvider.getTmpP12TruststoreFile();
+        assertThat(p12TruststoreSaved.getCertificates()).hasSize(EXPECTED_THREE);
+    }
+
+
+
+    @AfterAll
+    static void removeTemporaryFiles() throws IOException {
+        TestCertificateProvider.removeTemporaryFiles();
+    }
+}
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/model/PemTruststoreTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/model/PemTruststoreTest.java
new file mode 100644
index 00000000..e7ffa093
--- /dev/null
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/model/PemTruststoreTest.java
@@ -0,0 +1,149 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.model;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import static org.onap.oom.truststoremerger.api.CertificateConstants.X_509_CERTIFICATE;
+
+import java.io.IOException;
+import java.security.cert.Certificate;
+import java.security.cert.CertificateEncodingException;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.Test;
+import org.onap.oom.truststoremerger.api.ExitableException;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAliasFactory;
+import org.onap.oom.truststoremerger.certification.file.TestCertificateProvider;
+import org.onap.oom.truststoremerger.certification.file.exception.MissingTruststoreException;
+import org.onap.oom.truststoremerger.certification.file.exception.TruststoreDataOperationException;
+import org.onap.oom.truststoremerger.certification.file.exception.WriteTruststoreFileException;
+
+class PemTruststoreTest {
+
+    public static final int EXPECTED_ONE = 1;
+    public static final int EXPECTED_THREE = 3;
+    public static final int FIRST_ELEMENT = 0;
+
+    private final CertificateWithAliasFactory factory = new CertificateWithAliasFactory();
+
+    @Test
+    void pemTruststoreShouldReadCertificatesFromFile() throws ExitableException {
+
+        //given
+        PemTruststore pemTruststore = TestCertificateProvider.getSamplePemTruststoreFile();
+
+        //when
+        List<CertificateWithAlias> certificates = pemTruststore.getCertificates();
+        Certificate certificate = certificates.get(FIRST_ELEMENT).getCertificate();
+        //then
+
+        assertThat(certificates).hasSize(EXPECTED_ONE);
+        assertThat(certificate.getType()).isEqualTo(X_509_CERTIFICATE);
+    }
+
+    @Test
+    void pemTruststoreShouldAddDifferentCertificates() throws IOException, ExitableException {
+
+        //given
+        PemTruststore tmpPemTruststoreFile = TestCertificateProvider.createTmpPemTruststoreFile();
+        List<CertificateWithAlias> jksTruststoreCertificates = TestCertificateProvider
+            .getSampleJksTruststoreFileWithUniqueAlias().getCertificates();
+        List<CertificateWithAlias> p12TruststoreCertificates = TestCertificateProvider.getSampleP12Truststore()
+            .getCertificates();
+
+        //when
+        tmpPemTruststoreFile.addCertificate(jksTruststoreCertificates);
+        tmpPemTruststoreFile.addCertificate(p12TruststoreCertificates);
+        tmpPemTruststoreFile.saveFile();
+
+        PemTruststore tmpPemTruststoreSaved = TestCertificateProvider.getTmpPemTruststoreFile();
+        List<CertificateWithAlias> addedCertificates = tmpPemTruststoreSaved.getCertificates();
+        Certificate certificate = addedCertificates.get(FIRST_ELEMENT).getCertificate();
+
+        //then
+        assertThat(addedCertificates).hasSize(EXPECTED_THREE);
+        assertThat(certificate.getType()).isEqualTo(X_509_CERTIFICATE);
+
+    }
+
+    @Test
+    void privateKeyIsSkippedWhileReadingCertificates() throws ExitableException {
+        //given
+        PemTruststore pemTruststore = TestCertificateProvider.getPemWithPrivateKeyTruststoreFile();
+
+        //when
+        List<CertificateWithAlias> certificate = pemTruststore.getCertificates();
+        //then
+
+        assertThat(certificate).hasSize(EXPECTED_ONE);
+    }
+
+    @Test
+    void shouldThrowExceptionWhenCannotSaveFile() throws IOException, ExitableException {
+        //given
+        PemTruststore tmpPemTruststoreFile = TestCertificateProvider.createTmpPemTruststoreFile();
+        List<CertificateWithAlias> pemTruststoreCertificates =
+            TestCertificateProvider.getSamplePemTruststoreFile().getCertificates();
+        //when
+        tmpPemTruststoreFile.addCertificate(pemTruststoreCertificates);
+        tmpPemTruststoreFile.getFile().setWritable(false);
+        //then
+        assertThatExceptionOfType(WriteTruststoreFileException.class)
+            .isThrownBy(tmpPemTruststoreFile::saveFile);
+
+    }
+
+    @Test
+    void shouldThrowExceptionWhenFileNotContainsCertificate() throws IOException {
+        //given
+        PemTruststore tmpPemTruststoreFile = TestCertificateProvider.createEmptyTmpPemTruststoreFile();
+        //when//then
+        assertThatExceptionOfType(MissingTruststoreException.class)
+            .isThrownBy(tmpPemTruststoreFile::getCertificates);
+    }
+
+    @Test
+    void shouldThrowExceptionWhenCannotConvertCertificateToPem() throws Exception {
+        //given
+        PemTruststore pemTruststore = TestCertificateProvider.createTmpPemTruststoreFile();
+        Certificate certificate = mock(Certificate.class);
+
+        when(certificate.getEncoded()).thenThrow(new CertificateEncodingException());
+
+        List<CertificateWithAlias> certificatesWithAliases = new ArrayList<>();
+        certificatesWithAliases.add(factory.createPemCertificate(certificate));
+        pemTruststore.addCertificate(certificatesWithAliases);
+
+        //when //then
+        assertThatExceptionOfType(TruststoreDataOperationException.class)
+            .isThrownBy(pemTruststore::saveFile);
+    }
+
+    @AfterAll
+    static void removeTemporaryFiles() throws IOException {
+        TestCertificateProvider.removeTemporaryFiles();
+    }
+
+}
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/model/TruststoreTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/model/TruststoreTest.java
new file mode 100644
index 00000000..eea1f9c7
--- /dev/null
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/model/TruststoreTest.java
@@ -0,0 +1,60 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.model;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.Test;
+import org.onap.oom.truststoremerger.certification.file.exception.CreateBackupException;
+import org.onap.oom.truststoremerger.certification.file.provider.PemCertificateController;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class TruststoreTest {
+
+    private static final String PEM_FILE_PATH = "src/test/resources/truststore.pem";
+    private static final String PEM_BACKUP_FILE_PATH = "src/test/resources/truststore.pem.bak";
+    private static final String BACKUP_EXTENSION = ".bak";
+
+
+    @Test
+    void createBackupShouldCreateFileWithExtension() throws CreateBackupException {
+        //given
+        File pemFile = new File(PEM_FILE_PATH);
+        Truststore truststore = new PemTruststore(pemFile, new PemCertificateController(pemFile));
+        //when
+        truststore.createBackup();
+
+        //then
+        File backupFile = new File(PEM_BACKUP_FILE_PATH);
+        assertThat(backupFile.getName().endsWith(BACKUP_EXTENSION)).isTrue();
+        assertThat(backupFile.isFile()).isTrue();
+    }
+
+
+    @AfterAll
+    static void removeBackupFile() throws IOException {
+        Files.deleteIfExists(Paths.get(PEM_BACKUP_FILE_PATH));
+    }
+
+}
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/FileManagerTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/FileManagerTest.java
index d348dd7e..c649ba68 100644
--- a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/FileManagerTest.java
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/FileManagerTest.java
@@ -33,12 +33,13 @@ class FileManagerTest {
 
     @ParameterizedTest
     @CsvSource(value = {
-            "opt/app/truststore.jks:.jks",
-            "opt/app/truststore.p12:.p12",
-            "opt/app/truststore.pem:.pem",
-            "opt/app/truststore:''",
+        "opt/app/truststore.jks:.jks",
+        "opt/app/truststore.p12:.p12",
+        "opt/app/truststore.pem:.pem",
+        "opt/app/truststore.PEM:.pem",
+        "opt/app/truststore:''",
     }, delimiter = ':')
-    void shouldReturnCorrectExtension(String filePath, String expectedExtension){
+    void shouldReturnCorrectExtension(String filePath, String expectedExtension) {
         String extension = fileManager.getExtension(new File(filePath));
         assertThat(extension).isEqualTo(expectedExtension);
     }
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/JavaCertificateStoreControllerTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/JavaCertificateStoreControllerTest.java
new file mode 100644
index 00000000..8ee77ef2
--- /dev/null
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/JavaCertificateStoreControllerTest.java
@@ -0,0 +1,59 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.provider;
+
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.onap.oom.truststoremerger.certification.file.TestCertificateProvider.getSampleJksTruststoreFile;
+
+import java.util.List;
+import org.junit.jupiter.api.Test;
+import org.onap.oom.truststoremerger.api.ExitableException;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.TestCertificateProvider;
+import org.onap.oom.truststoremerger.certification.file.exception.AliasConflictException;
+import org.onap.oom.truststoremerger.certification.file.exception.MissingTruststoreException;
+import org.onap.oom.truststoremerger.certification.file.model.JavaTruststore;
+
+class JavaCertificateStoreControllerTest {
+
+
+    @Test
+    void throwExceptionWhenAliasConflictDetected() throws Exception {
+        //given
+        JavaTruststore p12Truststore = TestCertificateProvider.getSampleP12Truststore();
+        List<CertificateWithAlias> jksTruststoreCertificates = getSampleJksTruststoreFile().getCertificates();
+
+        //when //then
+        assertThatExceptionOfType(AliasConflictException.class)
+            .isThrownBy(() -> p12Truststore.addCertificate(jksTruststoreCertificates));
+    }
+
+
+    @Test
+    void throwExceptionWhenFileNotContainsTruststoreEntry() throws ExitableException {
+        //given
+        JavaTruststore p12Truststore = TestCertificateProvider.getSampleP12Keystore();
+
+        //when//then
+        assertThatExceptionOfType(MissingTruststoreException.class)
+            .isThrownBy(p12Truststore::getCertificates);
+    }
+
+}
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReaderTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReaderTest.java
index 712935ac..40eda4dd 100644
--- a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReaderTest.java
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/PasswordReaderTest.java
@@ -22,6 +22,7 @@ package org.onap.oom.truststoremerger.certification.file.provider;
 import org.junit.jupiter.api.Test;
 
 import java.io.File;
+import org.onap.oom.truststoremerger.certification.file.exception.PasswordReaderException;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/PemCertificateControllerTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/PemCertificateControllerTest.java
new file mode 100644
index 00000000..080fcca3
--- /dev/null
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/PemCertificateControllerTest.java
@@ -0,0 +1,95 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.provider;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+import java.io.File;
+import java.io.IOException;
+import java.security.cert.Certificate;
+import java.util.List;
+import java.util.stream.Collectors;
+import org.junit.jupiter.api.Test;
+import org.onap.oom.truststoremerger.api.ExitableException;
+import org.onap.oom.truststoremerger.certification.file.provider.entry.CertificateWithAlias;
+import org.onap.oom.truststoremerger.certification.file.TestCertificateProvider;
+import org.onap.oom.truststoremerger.certification.file.exception.MissingTruststoreException;
+import org.onap.oom.truststoremerger.certification.file.exception.TruststoreDataOperationException;
+import org.onap.oom.truststoremerger.certification.file.model.PemTruststore;
+
+class PemCertificateControllerTest {
+
+    @Test
+    void getNotEmptyCertificateListShouldThrowExceptionWhenFileNotContainsCertificate() {
+        //given
+        File emptyPemFile = TestCertificateProvider.getEmptyPemTruststoreFile().getFile();
+        PemCertificateController pemCertificateController = new PemCertificateController(emptyPemFile);
+        //when//then
+        assertThatExceptionOfType(MissingTruststoreException.class)
+            .isThrownBy(pemCertificateController::getNotEmptyCertificateList);
+    }
+
+    @Test
+    void transformToStringInPemFormatShouldCorrectlyTransform() throws ExitableException, IOException {
+        //given
+        PemTruststore pemTruststore = TestCertificateProvider.getSamplePemTruststoreFile();
+        List<CertificateWithAlias> wrappedCertificates = pemTruststore.getCertificates();
+        File notEmptyPemFile = pemTruststore.getFile();
+        List<Certificate> certificateList = unWrapCertificate(wrappedCertificates);
+        PemCertificateController pemCertificateController = new PemCertificateController(notEmptyPemFile);
+        String expected = TestCertificateProvider.getExpectedPemCertificateAsString();
+
+        //when
+        String certificateTransformed = pemCertificateController.transformToStringInPemFormat(certificateList);
+
+        //then
+        assertThat(certificateTransformed).isEqualTo(expected);
+    }
+
+    @Test
+    void fileNotContainsPemCertificateShouldReturnTrueIfFileNotContainsCertificate()
+        throws TruststoreDataOperationException {
+        //given
+        File emptyPemFile = TestCertificateProvider.getEmptyPemTruststoreFile().getFile();
+        PemCertificateController pemCertificateController = new PemCertificateController(emptyPemFile);
+        //when//then
+        assertThat(pemCertificateController.isFileWithoutPemCertificate()).isTrue();
+    }
+
+    @Test
+    void fileNotContainsPemCertificateShouldReturnFalseIfFileContainsCertificate()
+        throws TruststoreDataOperationException {
+        //given
+        File notEmptyPemFile = TestCertificateProvider.getSamplePemTruststoreFile().getFile();
+        PemCertificateController pemCertificateController = new PemCertificateController(notEmptyPemFile);
+
+        //when//then
+        assertThat(pemCertificateController.isFileWithoutPemCertificate()).isFalse();
+    }
+
+    private List<Certificate> unWrapCertificate(List<CertificateWithAlias> certificateWithAliases) {
+        return certificateWithAliases
+            .stream()
+            .map(CertificateWithAlias::getCertificate)
+            .collect(Collectors.toList());
+    }
+
+}
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFileFactoryTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFactoryTest.java
index f00b2bc4..b2063cc3 100644
--- a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFileFactoryTest.java
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFactoryTest.java
@@ -24,25 +24,27 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.junit.jupiter.MockitoExtension;
-import org.onap.oom.truststoremerger.certification.file.JksTruststore;
-import org.onap.oom.truststoremerger.certification.file.P12Truststore;
-import org.onap.oom.truststoremerger.certification.file.PemTruststore;
-import org.onap.oom.truststoremerger.certification.file.TruststoreFile;
+import org.onap.oom.truststoremerger.certification.file.TruststoreFileFactory;
+import org.onap.oom.truststoremerger.certification.file.model.JavaTruststore;
+import org.onap.oom.truststoremerger.certification.file.model.PemTruststore;
+import org.onap.oom.truststoremerger.certification.file.model.Truststore;
+import org.onap.oom.truststoremerger.certification.file.exception.KeystoreInstanceException;
+import org.onap.oom.truststoremerger.certification.file.exception.LoadTruststoreException;
 
 import java.io.File;
+import org.onap.oom.truststoremerger.certification.file.exception.PasswordReaderException;
+import org.onap.oom.truststoremerger.certification.file.exception.TruststoreFileFactoryException;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
 @ExtendWith(MockitoExtension.class)
-class TruststoreFileFactoryTest {
+class TruststoreFactoryTest {
 
     private static final String TRUSTSTORE_JKS_PATH = "src/test/resources/truststore-jks.jks";
     private static final String TRUSTSTORE_JKS_PASS_PATH = "src/test/resources/truststore-jks.pass";
-    private static final String TRUSTSTORE_JKS_PASS = "EOyuFbuYDyq_EhpboM72RHua";
     private static final String TRUSTSTORE_P12_PATH = "src/test/resources/truststore-p12.p12";
     private static final String TRUSTSTORE_P12_PASS_PATH = "src/test/resources/truststore-p12.pass";
-    private static final String TRUSTSTORE_P12_PASS = "88y9v5D8H3SG6bZWRVHDfOAo";
     private static final String TRUSTSTORE_PEM_PATH = "src/test/resources/truststore.pem";
     private static final String EMPTY_PASS_PATH = "";
     private static final String TRUSTSTORE_UNKNOWN_EXTENSION_PATH = "src/test/resources/truststore-jks.unknown";
@@ -56,28 +58,28 @@ class TruststoreFileFactoryTest {
     }
 
     @Test
-    void shouldReturnCorrectJksTruststoreForJksFile() throws TruststoreFileFactoryException, PasswordReaderException {
-        TruststoreFile truststore = truststoreFileFactory
+    void shouldReturnCorrectJksTruststoreForJksFile()
+        throws LoadTruststoreException, PasswordReaderException, TruststoreFileFactoryException, KeystoreInstanceException {
+        Truststore truststore = truststoreFileFactory
                 .create(TRUSTSTORE_JKS_PATH, TRUSTSTORE_JKS_PASS_PATH);
-        assertThat(truststore).isInstanceOf(JksTruststore.class);
-        JksTruststore jksTruststore = (JksTruststore) truststore;
-        assertThat(jksTruststore.getPassword()).isEqualTo(TRUSTSTORE_JKS_PASS);
-        assertThat(jksTruststore.getTruststoreFile()).isEqualTo(new File(TRUSTSTORE_JKS_PATH));
+        assertThat(truststore).isInstanceOf(JavaTruststore.class);
+        JavaTruststore jksTruststore = (JavaTruststore) truststore;
+        assertThat(jksTruststore.getFile()).isEqualTo(new File(TRUSTSTORE_JKS_PATH));
     }
 
     @Test
-    void shouldReturnCorrectP12TruststoreForP12File() throws TruststoreFileFactoryException, PasswordReaderException {
-        TruststoreFile truststore = truststoreFileFactory
+    void shouldReturnCorrectP12TruststoreForP12File()
+        throws LoadTruststoreException, PasswordReaderException, TruststoreFileFactoryException, KeystoreInstanceException {
+        Truststore truststore = truststoreFileFactory
                 .create(TRUSTSTORE_P12_PATH,
                         TRUSTSTORE_P12_PASS_PATH);
-        assertThat(truststore).isInstanceOf(P12Truststore.class);
-        P12Truststore jksTruststore = (P12Truststore) truststore;
-        assertThat(jksTruststore.getPassword()).isEqualTo(TRUSTSTORE_P12_PASS);
+        assertThat(truststore).isInstanceOf(JavaTruststore.class);
     }
 
     @Test
-    void shouldReturnCorrectPemTruststoreForPemFile() throws TruststoreFileFactoryException, PasswordReaderException {
-        TruststoreFile truststore = truststoreFileFactory
+    void shouldReturnCorrectPemTruststoreForPemFile()
+        throws LoadTruststoreException, PasswordReaderException, TruststoreFileFactoryException, KeystoreInstanceException {
+        Truststore truststore = truststoreFileFactory
                 .create(TRUSTSTORE_PEM_PATH,
                         EMPTY_PASS_PATH);
         assertThat(truststore).isInstanceOf(PemTruststore.class);
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFilesListProviderTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFilesListProviderTest.java
index 034e1b32..0dadcfef 100644
--- a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFilesListProviderTest.java
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/TruststoreFilesListProviderTest.java
@@ -22,15 +22,19 @@ package org.onap.oom.truststoremerger.certification.file.provider;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.onap.oom.truststoremerger.certification.file.JksTruststore;
-import org.onap.oom.truststoremerger.certification.file.P12Truststore;
-import org.onap.oom.truststoremerger.certification.file.PemTruststore;
-import org.onap.oom.truststoremerger.certification.file.TruststoreFile;
-import org.onap.oom.truststoremerger.certification.file.TruststoreFileWithPassword;
+import org.onap.oom.truststoremerger.certification.file.TruststoreFileFactory;
+import org.onap.oom.truststoremerger.certification.file.TruststoreFilesListProvider;
+import org.onap.oom.truststoremerger.certification.file.model.JavaTruststore;
+import org.onap.oom.truststoremerger.certification.file.model.PemTruststore;
+import org.onap.oom.truststoremerger.certification.file.model.Truststore;
+import org.onap.oom.truststoremerger.certification.file.exception.KeystoreInstanceException;
+import org.onap.oom.truststoremerger.certification.file.exception.LoadTruststoreException;
 
 import java.io.File;
 import java.util.Arrays;
 import java.util.List;
+import org.onap.oom.truststoremerger.certification.file.exception.PasswordReaderException;
+import org.onap.oom.truststoremerger.certification.file.exception.TruststoreFileFactoryException;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -38,10 +42,8 @@ class TruststoreFilesListProviderTest {
 
     private static final String TRUSTSTORE_JKS_PATH = "src/test/resources/truststore-jks.jks";
     private static final String TRUSTSTORE_JKS_PASS_PATH = "src/test/resources/truststore-jks.pass";
-    private static final String TRUSTSTORE_JKS_PASS = "EOyuFbuYDyq_EhpboM72RHua";
     private static final String TRUSTSTORE_P12_PATH = "src/test/resources/truststore-p12.p12";
     private static final String TRUSTSTORE_P12_PASS_PATH = "src/test/resources/truststore-p12.pass";
-    private static final String TRUSTSTORE_P12_PASS = "88y9v5D8H3SG6bZWRVHDfOAo";
     private static final String TRUSTSTORE_PEM_PATH = "src/test/resources/truststore.pem";
     private static final String EMPTY_PASS_PATH = "";
 
@@ -54,37 +56,32 @@ class TruststoreFilesListProviderTest {
     }
 
     @Test
-    void shouldReturnTruststoreFilesList() throws PasswordReaderException, TruststoreFileFactoryException {
+    void shouldReturnTruststoreFilesList()
+        throws TruststoreFileFactoryException, PasswordReaderException, LoadTruststoreException, KeystoreInstanceException {
         List<String> truststorePaths = Arrays.asList(TRUSTSTORE_JKS_PATH, TRUSTSTORE_P12_PATH, TRUSTSTORE_PEM_PATH);
         List<String> truststorePasswordPaths = Arrays.asList(TRUSTSTORE_JKS_PASS_PATH, TRUSTSTORE_P12_PASS_PATH, EMPTY_PASS_PATH);
-        List<TruststoreFile> truststoreFilesList = truststoreFilesListProvider.getTruststoreFilesList(truststorePaths, truststorePasswordPaths);
+        List<Truststore> truststoreFilesList = truststoreFilesListProvider.getTruststoreFilesList(truststorePaths, truststorePasswordPaths);
         assertThat(truststoreFilesList.size()).isEqualTo(3);
-        assertCorrectJksTruststore(truststoreFilesList.get(0), TRUSTSTORE_JKS_PATH, TRUSTSTORE_JKS_PASS);
-        assertCorrectP12Truststore(truststoreFilesList.get(1), TRUSTSTORE_P12_PATH, TRUSTSTORE_P12_PASS);
+        assertCorrectJksTruststore(truststoreFilesList.get(0), TRUSTSTORE_JKS_PATH);
+        assertCorrectP12Truststore(truststoreFilesList.get(1), TRUSTSTORE_P12_PATH);
         assertCorrectPemTruststore(truststoreFilesList.get(2), TRUSTSTORE_PEM_PATH);
     }
 
-    private void assertCorrectJksTruststore(TruststoreFile truststoreFile, String truststorePath, String truststorePass) {
-        assertCorrectTypeAndTruststorePath(truststoreFile, truststorePath, JksTruststore.class);
-        assertContainsCorrectPassword(truststoreFile, truststorePass);
+    private void assertCorrectJksTruststore(Truststore truststore, String truststorePath) {
+        assertCorrectTypeAndTruststorePath(truststore, truststorePath, JavaTruststore.class);
     }
 
-    private void assertCorrectP12Truststore(TruststoreFile truststoreFile, String truststorePath, String truststorePass) {
-        assertCorrectTypeAndTruststorePath(truststoreFile, truststorePath, P12Truststore.class);
-        assertContainsCorrectPassword(truststoreFile, truststorePass);
+    private void assertCorrectP12Truststore(Truststore truststore, String truststorePath) {
+        assertCorrectTypeAndTruststorePath(truststore, truststorePath, JavaTruststore.class);
     }
 
-    private void assertCorrectPemTruststore(TruststoreFile truststoreFile, String truststorePath) {
-        assertCorrectTypeAndTruststorePath(truststoreFile, truststorePath, PemTruststore.class);
+    private void assertCorrectPemTruststore(Truststore truststore, String truststorePath) {
+        assertCorrectTypeAndTruststorePath(truststore, truststorePath, PemTruststore.class);
     }
 
-    private void assertCorrectTypeAndTruststorePath(TruststoreFile truststoreFile, String truststorePath, Class<?> truststoreType) {
-        assertThat(truststoreFile).isInstanceOf(truststoreType);
-        assertThat(truststoreFile.getTruststoreFile()).isEqualTo(new File(truststorePath));
+    private void assertCorrectTypeAndTruststorePath(Truststore truststore, String truststorePath, Class<?> truststoreType) {
+        assertThat(truststore).isInstanceOf(truststoreType);
+        assertThat(truststore.getFile()).isEqualTo(new File(truststorePath));
     }
 
-    private void assertContainsCorrectPassword(TruststoreFile truststoreFile, String truststorePass) {
-        TruststoreFileWithPassword truststoreFileWithPassword = (TruststoreFileWithPassword) truststoreFile;
-        assertThat(truststoreFileWithPassword.getPassword()).isEqualTo(truststorePass);
-    }
 }
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/entry/PemAliasGeneratorTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/entry/PemAliasGeneratorTest.java
new file mode 100644
index 00000000..0897de29
--- /dev/null
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/file/provider/entry/PemAliasGeneratorTest.java
@@ -0,0 +1,58 @@
+/*============LICENSE_START=======================================================
+ * oom-truststore-merger
+ * ================================================================================
+ * Copyright (C) 2020 Nokia. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.oom.truststoremerger.certification.file.provider.entry;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.HashSet;
+import java.util.Set;
+import org.junit.jupiter.api.Test;
+
+class PemAliasGeneratorTest {
+
+    private final static String PREFIX_ALIAS_NAME = "pem-trusted-certificate-";
+    static final int GENERATED_ALIASES_NUMBER = 100;
+
+    @Test
+    void aliasHasPemPrefix() {
+        //given
+        PemAliasGenerator pemAliasGenerator = PemAliasGenerator.getInstance();
+        //when
+        String alias = pemAliasGenerator.getAlias();
+        //then
+        assertThat(alias.contains(PREFIX_ALIAS_NAME)).isTrue();
+    }
+
+    @Test
+    void generatedAliasesHaveUniqNames() {
+        //given
+        PemAliasGenerator pemAliasGenerator = PemAliasGenerator.getInstance();
+        Set<String> aliases = new HashSet<>();
+
+        //when
+        for (int i = 0; i < GENERATED_ALIASES_NUMBER; i++) {
+            aliases.add(pemAliasGenerator.getAlias());
+        }
+
+        //then
+        assertThat(aliases).hasSize(GENERATED_ALIASES_NUMBER);
+    }
+
+}
diff --git a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/path/TruststoresPathsProviderTest.java b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/path/TruststoresPathsProviderTest.java
index 945a1077..38422d5c 100644
--- a/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/path/TruststoresPathsProviderTest.java
+++ b/trustStoreMerger/src/test/java/org/onap/oom/truststoremerger/certification/path/TruststoresPathsProviderTest.java
@@ -30,8 +30,8 @@ import java.util.Optional;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.mockito.Mockito.when;
-import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_ENV;
-import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_PASSWORDS_ENV;
+import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_PATHS_ENV;
+import static org.onap.oom.truststoremerger.api.ConfigurationEnvs.TRUSTSTORES_PASSWORDS_PATHS_ENV;
 
 
 @ExtendWith(MockitoExtension.class)
@@ -94,11 +94,11 @@ class TruststoresPathsProviderTest {
     }
 
     private void mockTruststoresEnv(String truststores) {
-        mockEnv(truststores, TRUSTSTORES_ENV);
+        mockEnv(truststores, TRUSTSTORES_PATHS_ENV);
     }
 
     private void mockTruststoresPasswordsEnv(String truststoresPasswords) {
-        mockEnv(truststoresPasswords, TRUSTSTORES_PASSWORDS_ENV);
+        mockEnv(truststoresPasswords, TRUSTSTORES_PASSWORDS_PATHS_ENV);
     }
 
     private void mockEnv(String envValue, String envName) {
diff --git a/trustStoreMerger/src/test/resources/empty-truststore.pem b/trustStoreMerger/src/test/resources/empty-truststore.pem
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/trustStoreMerger/src/test/resources/empty-truststore.pem
@@ -0,0 +1 @@
+
diff --git a/trustStoreMerger/src/test/resources/keystore.p12 b/trustStoreMerger/src/test/resources/keystore.p12
new file mode 100644
index 00000000..bc047a98
--- /dev/null
+++ b/trustStoreMerger/src/test/resources/keystore.p12
diff --git a/trustStoreMerger/src/test/resources/truststore-jks-uniq.jks b/trustStoreMerger/src/test/resources/truststore-jks-uniq.jks
new file mode 100644
index 00000000..76ce8bc4
--- /dev/null
+++ b/trustStoreMerger/src/test/resources/truststore-jks-uniq.jks
diff --git a/trustStoreMerger/src/test/resources/truststore-with-private-key.pem b/trustStoreMerger/src/test/resources/truststore-with-private-key.pem
new file mode 100644
index 00000000..95179062
--- /dev/null
+++ b/trustStoreMerger/src/test/resources/truststore-with-private-key.pem
@@ -0,0 +1,56 @@
+-----BEGIN CERTIFICATE-----
+MIIEszCCAxugAwIBAgIUE+27eIlr12tQ+AMxkJTf2Y+ycOEwDQYJKoZIhvcNAQEL
+BQAwYTEjMCEGCgmSJomT8ixkAQEME2MtMDRjYmE2YjhhMDQ5ODEyNGQxFTATBgNV
+BAMMDE1hbmFnZW1lbnRDQTEjMCEGA1UECgwaRUpCQ0EgQ29udGFpbmVyIFF1aWNr
+c3RhcnQwHhcNMjAwNzA4MTIzODU4WhcNMzAwNzA4MTIzODU4WjBhMSMwIQYKCZIm
+iZPyLGQBAQwTYy0wNGNiYTZiOGEwNDk4MTI0ZDEVMBMGA1UEAwwMTWFuYWdlbWVu
+dENBMSMwIQYDVQQKDBpFSkJDQSBDb250YWluZXIgUXVpY2tzdGFydDCCAaIwDQYJ
+KoZIhvcNAQEBBQADggGPADCCAYoCggGBALTlx22Ld87VO5QgkD7OJvx81a8xLRWt
+b4cqmLSBRKw+jTjX4fHCtLh98hXNtYXJ9nxPa2t8MKR/I00Wf1razX1IYN9H/diV
+uICjyMxDyK6nwEMpqaWiQgOQx1N4TjNhr19ULTbyFLQMVfXy1OrTsfoWQ2omvRxN
+LIoVKwPHd92KG6iqJDZU14ErfA6UtypDV+4rOKQBh0JrfFI/KxKFKRH3e0oDxD8c
+PIOUpYVccVv/4Gbc0ZRs8KK0uPZN73LlQccYzPrSk/VAUeuZ52Wqk6dNrq5FHSCe
+EwPbx6aqgLwhTLlYAJqmYuDsGU9ZL09buCVKim1pjZiPaoaYAvv3KHdjEKAu9NxF
+dezd4JZ24hqYCA7EGnKgyjHxA0SiD/B8f+aBdRGDZbMlH1gKFKivjuHSfPwRv6Op
+p8ykEzk3yp0RcqSflVPg0mj+LPViYo/loLLOLybFFR7BetyFieN5QV7BKRyfc7Qi
+Se6Idh1nLIrYR9ek8BDkEE9u/JiTT0gP3QIDAQABo2MwYTAPBgNVHRMBAf8EBTAD
+AQH/MB8GA1UdIwQYMBaAFDYtHGSe9lYaC9+WnNT91wuiMlkjMB0GA1UdDgQWBBQ2
+LRxknvZWGgvflpzU/dcLojJZIzAOBgNVHQ8BAf8EBAMCAYYwDQYJKoZIhvcNAQEL
+BQADggGBAIcLj76GVhYSuVaWMMCVlVl8rHhYYufT9z2X7G/0D1G655/dAeAJLltL
+S4T7SZI44XKfVH4ztc4TO6OEMLZzslcfDzv/tUzL4EOsXtBTpsK9JgHP2lzCE+aj
+a7uxn5SGWlu0YmT/++2d+QYaVVAjqalal8NsppOYCh8GB84TXbQjOMWcR9YBozZf
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+9envV9HcJw==
+-----END CERTIFICATE-----
+-----BEGIN RSA PRIVATE KEY-----
+MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQCeCRM315FGH1Fa
+nlHRo/JfNwPi+xAor+cC4b/5qEIsGI9Zwgg9rzs/k9XOyUYoWMCNzn8c3nTYhd8h
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+E26Xy2D/AgMBAAECggEABUJeDlyxK/k81twv8t8W4M5O5c3fIst/z5u9rMxJr3f9
+xUnsxki/mwULd39BQ3R4q/90QXyxvMbvvwxoY91mfCcwN8vd/C6Pb68JgkYGF0Yv
+d/m0OC+lPc5g31DPEE5FEcsKovSyrcpvahWAIKYWXuLeIstK5GV48s4zZZWxAIJa
+7IhLst4I3Y7B6vmPHCutOxL6VXPllhe1gAI/tRWH0Hpbk/KiN0jGirTWo9FrNgAZ
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+pBgrffaab+qMDuziQ2SyHlm1eCnQGbl/++9UPAHZ6QKBgQDQIpVwqzfDsGxsBFo5
+y6wL5uWP8oiDoAkTjX41tgFy5G+ccHaIle/N8U+yrMkgW4tKKYFdREfA9eNxLbsB
+Dy6MkYlbE6cWbcf42QN7/Nn0jWBVrSNBssAPdQYtCJw+07/Qn1rWVIkTNHpqvEV7
+T9+JgLtSD9d3yMEeW/wWpF0PBQKBgQDCYQEQ2iwqyMtsd5GRZFXboBWAVdjfuEd9
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+pu46AsFKmHlLk+OEfP3crJRdowkZarGqPvn6UY50vse27qZOSYI+usCFAoGBAJhF
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+WHX9ctZHBhIe4LC9gqrQIyBg1mk95wl0aLWETCRfZXM8kYmDenN441tqUOIp0CHq
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+riR19yvlWk9tsswdefhyIb36/2qX7+4cQLZsD9b/nVF+GVwbXFgn/qjRQyds+YUD
+dpD/KciWewZRhlQvWChEH/hZrzauBnkE0qcMURW6Xf7NHn/7d+jembEc3bkyjnEI
+6yNDF7D4l5W6gvqgiN5VSM8=
+-----END RSA PRIVATE KEY-----