Improve exception flow

Issue-ID: AAF-995
Signed-off-by: Bartosz Gardziejewski <bartosz.gardziejewski@nokia.com>
Change-Id: I4d690fbe27364bc50b97ab42e64e610566d93ca0

14 files changed, 305 insertions, 98 deletions

diff --git a/certService/src/main/java/org/onap/aaf/certservice/api/CertificationService.java b/certService/src/main/java/org/onap/aaf/certservice/api/CertificationService.java
index 75fc0f52..d1a4a17a 100644
--- a/certService/src/main/java/org/onap/aaf/certservice/api/CertificationService.java
+++ b/certService/src/main/java/org/onap/aaf/certservice/api/CertificationService.java
@@ -24,11 +24,9 @@ import com.google.gson.Gson;
 import org.onap.aaf.certservice.certification.CertificationModelFactory;
 import org.onap.aaf.certservice.certification.CsrModelFactory;
 import org.onap.aaf.certservice.certification.CsrModelFactory.StringBase64;
-import org.onap.aaf.certservice.certification.exceptions.CsrDecryptionException;
-import org.onap.aaf.certservice.certification.exceptions.PemDecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.DecryptionException;
 import org.onap.aaf.certservice.certification.model.CertificationModel;
 import org.onap.aaf.certservice.certification.model.CsrModel;
-import org.onap.aaf.certservice.certification.model.ErrorResponseModel;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -68,35 +66,19 @@ public class CertificationService {
             @PathVariable String caName,
             @RequestHeader("CSR") String encodedCsr,
             @RequestHeader("PK") String encodedPrivateKey
-    ) {
+    ) throws DecryptionException {
+
         caName = caName.replaceAll("[\n|\r|\t]", "_");
         LOGGER.info("Received certificate signing request for CA named: {}", caName);
+        CsrModel csrModel = csrModelFactory.createCsrModel(
+                new StringBase64(encodedCsr),
+                new StringBase64(encodedPrivateKey)
+        );
+        LOGGER.debug("Received CSR meta data: \n{}", csrModel);
+        CertificationModel certificationModel = certificationModelFactory
+                .createCertificationModel(csrModel,caName);
+        return new ResponseEntity<>(new Gson().toJson(certificationModel), HttpStatus.OK);
 
-        try {
-            CsrModel csrModel = csrModelFactory.createCsrModel(
-                    new StringBase64(encodedCsr),
-                    new StringBase64(encodedPrivateKey)
-            );
-            LOGGER.debug("Received CSR meta data: \n{}", csrModel);
-            CertificationModel certificationModel = certificationModelFactory
-                    .createCertificationModel(csrModel,caName);
-            return new ResponseEntity<>(
-                    new Gson().toJson(certificationModel),
-                    HttpStatus.OK);
-        } catch (CsrDecryptionException e) {
-            LOGGER.error("Exception occurred during decoding certificate sign request:", e);
-            return getErrorResponseEntity("Wrong certificate signing request (CSR) format");
-        } catch (PemDecryptionException e) {
-            LOGGER.error("Exception occurred during decoding key:", e);
-            return getErrorResponseEntity("Wrong key (PK) format");
-        }
-    }
-
-    private ResponseEntity<String> getErrorResponseEntity(String errorMessage) {
-        ErrorResponseModel errorResponse = new ErrorResponseModel(errorMessage);
-        return new ResponseEntity<>(
-                new Gson().toJson(errorResponse),
-                HttpStatus.BAD_REQUEST);
     }
 
 
diff --git a/certService/src/main/java/org/onap/aaf/certservice/certification/CsrModelFactory.java b/certService/src/main/java/org/onap/aaf/certservice/certification/CsrModelFactory.java
index c1262e1e..6794bd6b 100644
--- a/certService/src/main/java/org/onap/aaf/certservice/certification/CsrModelFactory.java
+++ b/certService/src/main/java/org/onap/aaf/certservice/certification/CsrModelFactory.java
@@ -20,13 +20,13 @@
 
 package org.onap.aaf.certservice.certification;
 
-import java.io.IOException;
 import java.util.Base64;
 
 import org.bouncycastle.pkcs.PKCS10CertificationRequest;
 import org.bouncycastle.util.io.pem.PemObject;
 import org.onap.aaf.certservice.certification.exceptions.CsrDecryptionException;
-import org.onap.aaf.certservice.certification.exceptions.PemDecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.DecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.KeyDecryptionException;
 import org.onap.aaf.certservice.certification.model.CsrModel;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -37,22 +37,35 @@ import org.springframework.stereotype.Service;
 public class CsrModelFactory {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(CsrModelFactory.class);
-    private final PemObjectFactory pemObjectFactory = new PemObjectFactory();
+    private final PemObjectFactory pemObjectFactory
+            = new PemObjectFactory();
+    private final PKCS10CertificationRequestFactory certificationRequestFactory
+            = new PKCS10CertificationRequestFactory();
+
 
     public CsrModel createCsrModel(StringBase64 csr, StringBase64 privateKey)
-            throws CsrDecryptionException, PemDecryptionException {
+            throws DecryptionException {
         LOGGER.debug("Decoded CSR: \n{}", csr);
+        PKCS10CertificationRequest decodedCsr = decodeCsr(csr);
+        PemObject decodedPrivateKey = decodePrivateKey(privateKey);
+        return new CsrModel(decodedCsr, decodedPrivateKey);
+    }
 
-        try {
-            PemObject pemObject = pemObjectFactory.createPemObject(csr.asString());
-            PKCS10CertificationRequest decodedCsr = new PKCS10CertificationRequest(
-                    pemObject.getContent()
-            );
-            PemObject decodedPrivateKey = pemObjectFactory.createPemObject(privateKey.asString());
-            return new CsrModel(decodedCsr, decodedPrivateKey);
-        } catch (IOException e) {
-            throw new CsrDecryptionException("Incorrect CSR, decryption failed", e);
-        }
+    private PemObject decodePrivateKey(StringBase64 privateKey)
+            throws KeyDecryptionException {
+        return pemObjectFactory.createPemObject(privateKey.asString()).orElseThrow(
+                () -> new KeyDecryptionException("Incorrect Key, decryption failed")
+        );
+    }
+
+    private PKCS10CertificationRequest decodeCsr(StringBase64 csr)
+            throws CsrDecryptionException {
+        return pemObjectFactory.createPemObject(csr.asString())
+                .flatMap(
+                        certificationRequestFactory::createKCS10CertificationRequest
+                ).orElseThrow(
+                        () -> new CsrDecryptionException("Incorrect CSR, decryption failed")
+                );
     }
 
     public static class StringBase64 {
@@ -67,6 +80,7 @@ public class CsrModelFactory {
             return new String(decoder.decode(value));
         }
     }
+
 }
 
 
diff --git a/certService/src/main/java/org/onap/aaf/certservice/certification/PKCS10CertificationRequestFactory.java b/certService/src/main/java/org/onap/aaf/certservice/certification/PKCS10CertificationRequestFactory.java
new file mode 100644
index 00000000..8f89de2f
--- /dev/null
+++ b/certService/src/main/java/org/onap/aaf/certservice/certification/PKCS10CertificationRequestFactory.java
@@ -0,0 +1,38 @@
+/*
+ * ============LICENSE_START=======================================================
+ * PROJECT
+ * ================================================================================
+ * 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.aaf.certservice.certification;
+
+import org.bouncycastle.pkcs.PKCS10CertificationRequest;
+import org.bouncycastle.util.io.pem.PemObject;
+
+import java.io.IOException;
+import java.util.Optional;
+
+public class PKCS10CertificationRequestFactory {
+
+    public Optional<PKCS10CertificationRequest>  createKCS10CertificationRequest(PemObject pemObject) {
+        try {
+            return Optional.of(new PKCS10CertificationRequest(pemObject.getContent()));
+        } catch (IOException e) {
+            return Optional.empty();
+        }
+    }
+}
diff --git a/certService/src/main/java/org/onap/aaf/certservice/certification/PemObjectFactory.java b/certService/src/main/java/org/onap/aaf/certservice/certification/PemObjectFactory.java
index 61ea0aaf..514101b9 100644
--- a/certService/src/main/java/org/onap/aaf/certservice/certification/PemObjectFactory.java
+++ b/certService/src/main/java/org/onap/aaf/certservice/certification/PemObjectFactory.java
@@ -22,22 +22,21 @@ package org.onap.aaf.certservice.certification;
 
 import java.io.IOException;
 import java.io.StringReader;
+import java.util.Optional;
 
 import org.bouncycastle.util.io.pem.PemObject;
 import org.bouncycastle.util.io.pem.PemReader;
 
-import org.onap.aaf.certservice.certification.exceptions.PemDecryptionException;
-
 
 public class PemObjectFactory {
 
-    public PemObject createPemObject(String pem) throws PemDecryptionException {
+    public Optional<PemObject> createPemObject(String pem) {
 
         try (StringReader stringReader = new StringReader(pem);
              PemReader pemReader = new PemReader(stringReader)) {
-            return pemReader.readPemObject();
+            return Optional.ofNullable(pemReader.readPemObject());
         } catch (IOException e) {
-            throw new PemDecryptionException("Unable to create PEM", e);
+            return Optional.empty();
         }
     }
 
diff --git a/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/CertificationExceptionController.java b/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/CertificationExceptionController.java
new file mode 100644
index 00000000..7d2c43ed
--- /dev/null
+++ b/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/CertificationExceptionController.java
@@ -0,0 +1,56 @@
+/*
+ * ============LICENSE_START=======================================================
+ * PROJECT
+ * ================================================================================
+ * 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.aaf.certservice.certification.exceptions;
+
+import com.google.gson.Gson;
+import org.onap.aaf.certservice.certification.model.ErrorResponseModel;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+
+@ControllerAdvice
+public class CertificationExceptionController {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(CertificationExceptionController.class);
+
+    @ExceptionHandler(value = CsrDecryptionException.class)
+    public ResponseEntity<String> handle(CsrDecryptionException exception) {
+        LOGGER.error("Exception occurred during decoding certificate sign request:", exception);
+        return getErrorResponseEntity("Wrong certificate signing request (CSR) format");
+    }
+
+    @ExceptionHandler(value = KeyDecryptionException.class)
+    public ResponseEntity<String> handle(KeyDecryptionException exception) {
+        LOGGER.error("Exception occurred during decoding key:", exception);
+        return getErrorResponseEntity("Wrong key (PK) format");
+    }
+
+    private ResponseEntity<String> getErrorResponseEntity(String errorMessage) {
+        ErrorResponseModel errorResponse = new ErrorResponseModel(errorMessage);
+        return new ResponseEntity<>(
+                new Gson().toJson(errorResponse),
+                HttpStatus.BAD_REQUEST
+        );
+    }
+}
diff --git a/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/CsrDecryptionException.java b/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/CsrDecryptionException.java
index 2f3f3659..929fbdb6 100644
--- a/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/CsrDecryptionException.java
+++ b/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/CsrDecryptionException.java
@@ -24,4 +24,7 @@ public class CsrDecryptionException extends DecryptionException {
     public CsrDecryptionException(String message, Throwable cause) {
         super(message, cause);
     }
+    public CsrDecryptionException(String message) {
+        super(message);
+    }
 }
diff --git a/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/DecryptionException.java b/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/DecryptionException.java
index 67249cd5..8f5f48e6 100644
--- a/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/DecryptionException.java
+++ b/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/DecryptionException.java
@@ -24,4 +24,7 @@ public class DecryptionException extends Exception {
     public DecryptionException(String message, Throwable cause) {
         super(message, cause);
     }
+    public DecryptionException(String message) {
+        super(message);
+    }
 }
diff --git a/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/PemDecryptionException.java b/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/KeyDecryptionException.java
index 564660e5..15d53935 100644
--- a/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/PemDecryptionException.java
+++ b/certService/src/main/java/org/onap/aaf/certservice/certification/exceptions/KeyDecryptionException.java
@@ -20,9 +20,11 @@
 
 package org.onap.aaf.certservice.certification.exceptions;
 
-public class PemDecryptionException extends DecryptionException {
-    public PemDecryptionException(String message, Throwable cause) {
+public class KeyDecryptionException extends DecryptionException {
+    public KeyDecryptionException(String message, Throwable cause) {
         super(message, cause);
     }
-
+    public KeyDecryptionException(String message) {
+        super(message);
+    }
 }
diff --git a/certService/src/test/java/org/onap/aaf/certservice/api/CertificationServiceTest.java b/certService/src/test/java/org/onap/aaf/certservice/api/CertificationServiceTest.java
index 8ee88db5..0bb99d9f 100644
--- a/certService/src/test/java/org/onap/aaf/certservice/api/CertificationServiceTest.java
+++ b/certService/src/test/java/org/onap/aaf/certservice/api/CertificationServiceTest.java
@@ -30,7 +30,7 @@ import org.onap.aaf.certservice.certification.CsrModelFactory;
 import org.onap.aaf.certservice.certification.CsrModelFactory.StringBase64;
 import org.onap.aaf.certservice.certification.exceptions.CsrDecryptionException;
 import org.onap.aaf.certservice.certification.exceptions.DecryptionException;
-import org.onap.aaf.certservice.certification.exceptions.PemDecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.KeyDecryptionException;
 import org.onap.aaf.certservice.certification.model.CertificationModel;
 import org.onap.aaf.certservice.certification.model.CsrModel;
 import org.springframework.http.HttpStatus;
@@ -41,7 +41,7 @@ import java.util.Arrays;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
@@ -93,43 +93,41 @@ class CertificationServiceTest {
     }
 
     @Test
-    void shouldReturnBadRequestWhenCreatingCsrModelFails() throws DecryptionException {
+    void shouldThrowCsrDecryptionExceptionWhenCreatingCsrModelFails() throws DecryptionException {
         // given
+        String expectedMessage = "Incorrect CSR, decryption failed";
         when(csrModelFactory.createCsrModel(any(StringBase64.class), any(StringBase64.class)))
-                .thenThrow(new CsrDecryptionException("CSR creation fail",new IOException()));
+                .thenThrow(new CsrDecryptionException(expectedMessage,new IOException()));
 
         // when
-        ResponseEntity<String> testResponse =
-                certificationService.signCertificate("TestCa", "encryptedCSR", "encryptedPK");
+        Exception exception = assertThrows(
+                CsrDecryptionException.class, () -> certificationService.
+                        signCertificate("TestCa", "encryptedCSR", "encryptedPK")
+        );
 
-        String expectedMessage = "Wrong certificate signing request (CSR) format";
+        String actualMessage = exception.getMessage();
 
         // then
-        assertEquals(HttpStatus.BAD_REQUEST, testResponse.getStatusCode());
-        assertTrue(
-                testResponse.toString().contains(expectedMessage)
-        );
-
+        assertEquals(expectedMessage, actualMessage);
     }
 
     @Test
-    void shouldReturnBadRequestWhenCreatingPemModelFails() throws DecryptionException {
+    void shouldThrowPemDecryptionExceptionWhenCreatingPemModelFails() throws DecryptionException {
         // given
+        String expectedMessage = "Incorrect PEM, decryption failed";
         when(csrModelFactory.createCsrModel(any(StringBase64.class), any(StringBase64.class)))
-                .thenThrow(new PemDecryptionException("PEM creation fail",new IOException()));
+                .thenThrow(new KeyDecryptionException(expectedMessage,new IOException()));
 
         // when
-        ResponseEntity<String> testResponse =
-                certificationService.signCertificate("TestCa", "encryptedCSR", "encryptedPK");
+        Exception exception = assertThrows(
+                KeyDecryptionException.class, () -> certificationService.
+                        signCertificate("TestCa", "encryptedCSR", "encryptedPK")
+        );
 
-        String expectedMessage = "Wrong key (PK) format";
+        String actualMessage = exception.getMessage();
 
         // then
-        assertEquals(HttpStatus.BAD_REQUEST, testResponse.getStatusCode());
-        assertTrue(
-                testResponse.toString().contains(expectedMessage)
-        );
-
+        assertEquals(expectedMessage, actualMessage);
     }
 
 }
diff --git a/certService/src/test/java/org/onap/aaf/certservice/certification/CsrModelFactoryTest.java b/certService/src/test/java/org/onap/aaf/certservice/certification/CsrModelFactoryTest.java
index 065c7a0e..77594ed7 100644
--- a/certService/src/test/java/org/onap/aaf/certservice/certification/CsrModelFactoryTest.java
+++ b/certService/src/test/java/org/onap/aaf/certservice/certification/CsrModelFactoryTest.java
@@ -26,6 +26,7 @@ import org.junit.jupiter.api.Test;
 import org.onap.aaf.certservice.certification.CsrModelFactory.StringBase64;
 import org.onap.aaf.certservice.certification.exceptions.CsrDecryptionException;
 import org.onap.aaf.certservice.certification.exceptions.DecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.KeyDecryptionException;
 import org.onap.aaf.certservice.certification.model.CsrModel;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -33,6 +34,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.onap.aaf.certservice.certification.TestData.TEST_CSR;
 import static org.onap.aaf.certservice.certification.TestData.TEST_PK;
 import static org.onap.aaf.certservice.certification.TestData.TEST_WRONG_CSR;
+import static org.onap.aaf.certservice.certification.TestData.TEST_WRONG_PEM;
 
 
 class CsrModelFactoryTest {
@@ -66,9 +68,8 @@ class CsrModelFactoryTest {
         );
     }
 
-
     @Test
-    void shouldThrowCsrDecryptionExceptionWhenCsrAreIncorrect() {
+    void shouldThrowCsrDecryptionExceptionWhenCsrIsIncorrect() {
         // given
         String encoderPK = new String(Base64.encode(TEST_PK.getBytes()));
         String wrongCsr = new String(Base64.encode(TEST_WRONG_CSR.getBytes()));
@@ -86,4 +87,23 @@ class CsrModelFactoryTest {
         assertTrue(actualMessage.contains(expectedMessage));
     }
 
+    @Test
+    void shouldThrowKeyDecryptionExceptionWhenKeyIsIncorrect() {
+        // given
+        String encoderPK = new String(Base64.encode(TEST_WRONG_PEM.getBytes()));
+        String wrongCsr = new String(Base64.encode(TEST_CSR.getBytes()));
+
+        // when
+        Exception exception = assertThrows(
+                KeyDecryptionException.class, () -> csrModelFactory
+                        .createCsrModel(new StringBase64(wrongCsr), new StringBase64(encoderPK))
+        );
+
+        String expectedMessage = "Incorrect Key, decryption failed";
+        String actualMessage = exception.getMessage();
+
+        // then
+        assertTrue(actualMessage.contains(expectedMessage));
+    }
+
 }
diff --git a/certService/src/test/java/org/onap/aaf/certservice/certification/PemObjectFactoryTest.java b/certService/src/test/java/org/onap/aaf/certservice/certification/PemObjectFactoryTest.java
index 479c375b..0b70475c 100644
--- a/certService/src/test/java/org/onap/aaf/certservice/certification/PemObjectFactoryTest.java
+++ b/certService/src/test/java/org/onap/aaf/certservice/certification/PemObjectFactoryTest.java
@@ -23,8 +23,8 @@ package org.onap.aaf.certservice.certification;
 import org.bouncycastle.util.io.pem.PemObject;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.onap.aaf.certservice.certification.exceptions.CsrDecryptionException;
-import org.onap.aaf.certservice.certification.exceptions.PemDecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.DecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.KeyDecryptionException;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -45,9 +45,11 @@ class PemObjectFactoryTest {
     }
 
     @Test
-    void shouldTransformStringInToPemObjectAndBackToString() throws PemDecryptionException {
+    void shouldTransformStringInToPemObjectAndBackToString() throws DecryptionException {
         // when
-        PemObject pemObject = pemObjectFactory.createPemObject(TEST_PEM);
+        PemObject pemObject = pemObjectFactory.createPemObject(TEST_PEM).orElseThrow(
+                () -> new DecryptionException("Pem decryption failed")
+        );
         String parsedPemObject = pemObjectToString(pemObject);
 
         // then
@@ -56,12 +58,16 @@ class PemObjectFactoryTest {
 
     @Test
     void shouldThrowExceptionWhenParsingPemFailed() {
+        // given
+        String expectedMessage = "Unable to create PEM";
+
         // when
         Exception exception = assertThrows(
-                PemDecryptionException.class, () -> pemObjectFactory.createPemObject(TEST_WRONG_PEM)
+                DecryptionException.class, () -> pemObjectFactory.createPemObject(TEST_WRONG_PEM).orElseThrow(
+                        () -> new DecryptionException(expectedMessage)
+                )
         );
 
-        String expectedMessage = "Unable to create PEM";
         String actualMessage = exception.getMessage();
 
         // then
diff --git a/certService/src/test/java/org/onap/aaf/certservice/certification/TestUtils.java b/certService/src/test/java/org/onap/aaf/certservice/certification/TestUtils.java
index c2824c80..39554417 100644
--- a/certService/src/test/java/org/onap/aaf/certservice/certification/TestUtils.java
+++ b/certService/src/test/java/org/onap/aaf/certservice/certification/TestUtils.java
@@ -22,7 +22,7 @@ package org.onap.aaf.certservice.certification;
 
 import org.bouncycastle.util.io.pem.PemObject;
 import org.bouncycastle.util.io.pem.PemWriter;
-import org.onap.aaf.certservice.certification.exceptions.PemDecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.KeyDecryptionException;
 
 import java.io.IOException;
 import java.io.StringWriter;
@@ -33,7 +33,7 @@ public final class TestUtils {
     private TestUtils() {
     }
 
-    public static String pemObjectToString(PemObject pemObject) throws PemDecryptionException {
+    public static String pemObjectToString(PemObject pemObject) throws KeyDecryptionException {
         try (StringWriter output = new StringWriter()) {
             PemWriter pemWriter = new PemWriter(output);
             pemWriter.writeObject(pemObject);
@@ -41,7 +41,7 @@ public final class TestUtils {
             return output.getBuffer().toString();
 
         } catch (IOException e) {
-            throw new PemDecryptionException("Writing PAM Object to string failed", e);
+            throw new KeyDecryptionException("Writing PAM Object to string failed", e);
         }
     }
 }
diff --git a/certService/src/test/java/org/onap/aaf/certservice/certification/exception/CertificationExceptionControllerTest.java b/certService/src/test/java/org/onap/aaf/certservice/certification/exception/CertificationExceptionControllerTest.java
new file mode 100644
index 00000000..58e59f45
--- /dev/null
+++ b/certService/src/test/java/org/onap/aaf/certservice/certification/exception/CertificationExceptionControllerTest.java
@@ -0,0 +1,74 @@
+/*
+ * ============LICENSE_START=======================================================
+ * PROJECT
+ * ================================================================================
+ * 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.aaf.certservice.certification.exception;
+
+import com.google.gson.Gson;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.onap.aaf.certservice.certification.exceptions.CertificationExceptionController;
+import org.onap.aaf.certservice.certification.exceptions.CsrDecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.KeyDecryptionException;
+import org.onap.aaf.certservice.certification.model.ErrorResponseModel;
+import org.springframework.http.ResponseEntity;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class CertificationExceptionControllerTest {
+
+    private CertificationExceptionController certificationExceptionController;
+
+    @BeforeEach
+    void setUp() {
+        certificationExceptionController =
+                new CertificationExceptionController();
+    }
+
+    @Test
+    void shouldReturnResponseEntityWithAppropriateErrorMessageWhenGivenCsrDecryptionException() {
+        // given
+        String expectedMessage = "Wrong certificate signing request (CSR) format";
+        CsrDecryptionException csrDecryptionException = new CsrDecryptionException("test csr exception");
+
+        // when
+        ResponseEntity<String> responseEntity = certificationExceptionController.handle(csrDecryptionException);
+
+        ErrorResponseModel response = new Gson().fromJson(responseEntity.getBody(), ErrorResponseModel.class);
+
+        // then
+        assertEquals(expectedMessage, response.getErrorMessage());
+    }
+
+    @Test
+    void shouldReturnResponseEntityWithAppropriateErrorMessageWhenGivenKeyDecryptionException() {
+        // given
+        String expectedMessage = "Wrong key (PK) format";
+        KeyDecryptionException csrDecryptionException = new KeyDecryptionException("test pk exception");
+
+        // when
+        ResponseEntity<String> responseEntity = certificationExceptionController.handle(csrDecryptionException);
+
+        ErrorResponseModel response = new Gson().fromJson(responseEntity.getBody(), ErrorResponseModel.class);
+
+        // then
+        assertEquals(expectedMessage, response.getErrorMessage());
+    }
+
+}
diff --git a/certService/src/test/java/org/onap/aaf/certservice/certification/model/CsrModelTest.java b/certService/src/test/java/org/onap/aaf/certservice/certification/model/CsrModelTest.java
index 9d748150..7df785d2 100644
--- a/certService/src/test/java/org/onap/aaf/certservice/certification/model/CsrModelTest.java
+++ b/certService/src/test/java/org/onap/aaf/certservice/certification/model/CsrModelTest.java
@@ -24,10 +24,11 @@ import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
 import org.bouncycastle.pkcs.PKCS10CertificationRequest;
 import org.bouncycastle.util.io.pem.PemObject;
 import org.junit.jupiter.api.Test;
+import org.onap.aaf.certservice.certification.PKCS10CertificationRequestFactory;
 import org.onap.aaf.certservice.certification.PemObjectFactory;
 import org.onap.aaf.certservice.certification.exceptions.CsrDecryptionException;
 import org.onap.aaf.certservice.certification.exceptions.DecryptionException;
-import org.onap.aaf.certservice.certification.exceptions.PemDecryptionException;
+import org.onap.aaf.certservice.certification.exceptions.KeyDecryptionException;
 
 import java.io.IOException;
 
@@ -44,7 +45,10 @@ import static org.onap.aaf.certservice.certification.TestUtils.pemObjectToString
 
 class CsrModelTest {
 
-
+    private final PKCS10CertificationRequestFactory certificationRequestFactory
+            = new PKCS10CertificationRequestFactory();
+    private final PemObjectFactory pemObjectFactory
+            = new PemObjectFactory();
     @Test
     void shouldByConstructedAndReturnProperFields() throws DecryptionException, IOException {
         // given
@@ -70,7 +74,7 @@ class CsrModelTest {
     }
 
     @Test
-    void shouldThrowExceptionWhenKeyIsNotCorrect() throws PemDecryptionException ,IOException {
+    void shouldThrowExceptionWhenPublicKeyIsNotCorrect() throws KeyDecryptionException, IOException {
         // given
         PemObjectFactory pemObjectFactory = new PemObjectFactory();
         PKCS10CertificationRequest testCsr = mock(PKCS10CertificationRequest.class);
@@ -79,7 +83,9 @@ class CsrModelTest {
                 .thenReturn(wrongKryInfo);
         when(wrongKryInfo.getEncoded())
                 .thenThrow(new IOException());
-        PemObject testPrivateKey = pemObjectFactory.createPemObject(TEST_PK);
+        PemObject testPrivateKey = pemObjectFactory.createPemObject(TEST_PK).orElseThrow(
+                () -> new KeyDecryptionException("Private key decoding fail")
+        );
         CsrModel csrModel = new CsrModel(testCsr, testPrivateKey);
 
         // when
@@ -95,20 +101,26 @@ class CsrModelTest {
         assertTrue(actualMessage.contains(expectedMessage));
     }
 
-    private CsrModel generateTestCsrModel() throws PemDecryptionException, IOException {
-        PemObjectFactory pemObjectFactory = new PemObjectFactory();
-        PKCS10CertificationRequest testCsr = new PKCS10CertificationRequest(
-                pemObjectFactory.createPemObject(TEST_CSR).getContent()
+    private CsrModel generateTestCsrModel() throws DecryptionException {
+        PemObject testPrivateKey = pemObjectFactory.createPemObject(TEST_PK).orElseThrow(
+                () -> new DecryptionException("Incorrect Private Key, decryption failed")
         );
-        PemObject testPrivateKey = pemObjectFactory.createPemObject(TEST_PK);
+        PKCS10CertificationRequest testCsr = generateTestCertificationRequest();
         return new CsrModel(testCsr, testPrivateKey);
     }
 
-    private PemObject generateTestPublicKey() throws PemDecryptionException, IOException {
-        PemObjectFactory pemObjectFactory = new PemObjectFactory();
-        PKCS10CertificationRequest testCsr = new PKCS10CertificationRequest(
-                pemObjectFactory.createPemObject(TEST_CSR).getContent()
-        );
+    private PemObject generateTestPublicKey() throws DecryptionException, IOException {
+        PKCS10CertificationRequest testCsr = generateTestCertificationRequest();
         return new PemObject("PUBLIC KEY", testCsr.getSubjectPublicKeyInfo().getEncoded());
     }
+
+    private PKCS10CertificationRequest generateTestCertificationRequest() throws DecryptionException {
+        return pemObjectFactory.createPemObject(TEST_CSR)
+                .flatMap(
+                        certificationRequestFactory::createKCS10CertificationRequest
+                ).orElseThrow(
+                        () -> new DecryptionException("Incorrect CSR, decryption failed")
+                );
+    }
+
 }