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import javax.crypto.Cipher;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.GeneralSecurityException;
import java.security.SecureRandom;
import java.util.Arrays;
public class Crypto {
private static final String AES = "AES";
private static final int GCM_TAG_LENGTH = 16;
private static final int GCM_IV_LENGTH = 12;
private static final String AES_GCM_NO_PADDING = "AES/GCM/NoPadding";
public static void main(String[] args) {
if(args.length != 2) {
System.out.println("Usage: java Crypto value_to_encrypt key");
System.out.println("exit(1)");
System.exit(1);
}
String value = args[0];
String key = args[1];
String encrypted = encryptCloudConfigPassword(value, key);
System.out.println(encrypted);
}
/**
* encrypt a value and generate a keyfile
* if the keyfile is not found then a new one is created
*
* @throws GeneralSecurityException
*/
public static String encrypt (String value, String keyString) throws GeneralSecurityException {
SecretKeySpec sks = getSecretKeySpec (keyString);
Cipher cipher = Cipher.getInstance(AES_GCM_NO_PADDING);
byte[] initVector = new byte[GCM_IV_LENGTH];
(new SecureRandom()).nextBytes(initVector);
GCMParameterSpec spec = new GCMParameterSpec(GCM_TAG_LENGTH * java.lang.Byte.SIZE, initVector);
cipher.init(Cipher.ENCRYPT_MODE, sks, spec);
byte[] encoded = value.getBytes(java.nio.charset.StandardCharsets.UTF_8);
byte[] cipherText = new byte[initVector.length + cipher.getOutputSize(encoded.length)];
System.arraycopy(initVector, 0, cipherText, 0, initVector.length);
cipher.doFinal(encoded, 0, encoded.length, cipherText, initVector.length);
return byteArrayToHexString(cipherText);
}
public static String encryptCloudConfigPassword(String message, String key) {
try {
return Crypto.encrypt(message, key);
} catch (GeneralSecurityException e) {
return null;
}
}
private static SecretKeySpec getSecretKeySpec (String keyString) {
byte[] key = hexStringToByteArray (keyString);
return new SecretKeySpec (key, AES);
}
public static String byteArrayToHexString (byte[] b) {
StringBuilder sb = new StringBuilder(b.length * 2);
for (byte aB : b) {
int v = aB & 0xff;
if (v < 16) {
sb.append('0');
}
sb.append(Integer.toHexString(v));
}
return sb.toString ().toUpperCase ();
}
private static byte[] hexStringToByteArray (String s) {
byte[] b = new byte[s.length () / 2];
for (int i = 0; i < b.length; i++) {
int index = i * 2;
int v = Integer.parseInt (s.substring (index, index + 2), 16);
b[i] = (byte) v;
}
return b;
}
}
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