Program: 11631
Project: 11631
Buggy source:
/** 
 * Begins encryption checking.
 * @param encryptedSecret the encrypted shared secret
 * @param encryptedToken the encrypted token
 * @return the decrypted secret, or {@code null} if thisoperation did not complete successfully
 */
public byte[] begin(byte[] encryptedSecret,byte[] encryptedToken){
  try {
    Cipher keyPairCipher=Cipher.getInstance(KEY_PAIR_ALGO);
    keyPairCipher.init(Cipher.DECRYPT_MODE,this.kp.getPrivate());
    byte[] decryptedSecret=keyPairCipher.doFinal(encryptedSecret);
    byte[] decryptedToken=keyPairCipher.doFinal(encryptedToken);
    if (Arrays.equals(decryptedToken,this.token)) {
      SecretKey sharedSecret=new SecretKeySpec(decryptedSecret,SECRET_ALGO);
      IvParameterSpec iv=new IvParameterSpec(sharedSecret.getEncoded());
      this.cipherInit=mode -> {
        try {
          if (mode == Cipher.DECRYPT_MODE) {
            Cipher instance=this.decrypt.get();
            if (instance == null) {
              instance=Cipher.getInstance(CIPHER_NAME);
              instance.init(mode,sharedSecret,iv);
              this.decrypt.set(instance);
            }
            return instance;
          }
 else {
            Cipher instance=this.encrypt.get();
            if (instance == null) {
              instance=Cipher.getInstance(CIPHER_NAME);
              instance.init(mode,sharedSecret,iv);
              this.encrypt.set(instance);
            }
            return instance;
          }
        }
 catch (        Exception e) {
          throw new RuntimeException(e);
        }
      }
;
      cryptoEnabled=true;
      return decryptedSecret;
    }
  }
 catch (  NoSuchAlgorithmException|NoSuchPaddingException|InvalidKeyException|BadPaddingException|IllegalBlockSizeException e) {
    throw new RuntimeException(e);
  }
  return null;
}

Fixed version (ground truth):
/** 
 * Begins encryption checking.
 * @param encryptedSecret the encrypted shared secret
 * @param encryptedToken the encrypted token
 * @return the decrypted secret, or {@code null} if thisoperation did not complete successfully
 */
public byte[] begin(byte[] encryptedSecret,byte[] encryptedToken){
  try {
    Cipher keyPairCipher=Cipher.getInstance(KEY_PAIR_ALGO);
    keyPairCipher.init(Cipher.DECRYPT_MODE,this.kp.getPrivate());
    byte[] decryptedSecret=keyPairCipher.doFinal(encryptedSecret);
    byte[] decryptedToken=keyPairCipher.doFinal(encryptedToken);
    if (Arrays.equals(decryptedToken,this.token)) {
      SecretKey sharedSecret=new SecretKeySpec(decryptedSecret,SECRET_ALGO);
      IvParameterSpec iv=new IvParameterSpec(sharedSecret.getEncoded());
      this.cipherInit=mode -> {
        try {
          if (mode == Cipher.DECRYPT_MODE) {
            Cipher instance=this.decrypt.get();
            if (instance == null) {
              instance=Cipher.getInstance(CIPHER_NAME);
              instance.init(mode,sharedSecret,iv);
              this.decrypt.set(instance);
            }
            return instance;
          }
 else {
            Cipher instance=this.encrypt.get();
            if (instance == null) {
              instance=Cipher.getInstance(CIPHER_NAME);
              instance.init(mode,sharedSecret,iv);
              this.encrypt.set(instance);
            }
            return instance;
          }
        }
 catch (        Exception e) {
          throw new RuntimeException(e);
        }
      }
;
      return decryptedSecret;
    }
  }
 catch (  NoSuchAlgorithmException|NoSuchPaddingException|InvalidKeyException|BadPaddingException|IllegalBlockSizeException e) {
    throw new RuntimeException(e);
  }
  return null;
}