How to know whether data is being AES crypted or not?

Question

Hi Forum,
I used AES crypting with an initial vector and a SecretKey.
The problem is , for backward compatibility I need to check if the data had been crypted or not?
if not crypted I need to show them in plain readable format instead of decrypting them.
below is my Encryption/Decryption class
public class AesEncryption
    private  final String CRYPTO_ALGO_= "AES";
    Cipher aesCipher_;
// Create an 16-byte initialization vector
    private final byte[] initialVector_ = new byte[]{
                                                    (byte)0x8E, 0x12, 0x39, (byte)0x9C,
                                                          0x07, 0x72, 0x6F, 0x5A,
                                                    (byte)0x8E, 0x12, 0x39,(byte)0x9C,
                                                          0x07, 0x72, 0x6F, 0x5A
    private final SecretKey key_ = new SecretKeySpec(initialVector_, CRYPTO_ALGO_);
    public AesEncryption()
         *  Create a Cipher by specifying the following parameters
         *     Algorithm name - here it is AES
        try
             aesCipher_ = Cipher.getInstance(CRYPTO_ALGO_);
        catch (NoSuchAlgorithmException e)
            e.printStackTrace();
        catch (NoSuchPaddingException e)
            e.printStackTrace();
    public  String encryptPassword(String password)
        String strEncryptedText ="";
        try{
         *  Initialize the Cipher for Encryption with secret key
        aesCipher_.init(Cipher.ENCRYPT_MODE,key_);
         *   Encrypt the password
        byte[] byteDataToEncrypt = password.getBytes();
        byte[] byteCipherText = aesCipher_.doFinal(byteDataToEncrypt);
               strEncryptedText = new BASE64Encoder().encode(byteCipherText);
        catch (InvalidKeyException e)
             e.printStackTrace();
        catch (BadPaddingException e)
             e.printStackTrace();
        catch (IllegalBlockSizeException e)
             e.printStackTrace();
        return strEncryptedText;
    public String decryptPassword(String encryptedPassword)
        String strDecryptedText = "";
        try
             * Decrypt the Data
            byte[] byteCipherText = new BASE64Decoder().decodeBuffer(encryptedPassword.trim());
            aesCipher_.init(Cipher.DECRYPT_MODE,key_,aesCipher_.getParameters());
            byte[] byteDecryptedText = aesCipher_.doFinal(byteCipherText);
            strDecryptedText = new String(byteDecryptedText);
        catch (InvalidKeyException invalidKey)
             invalidKey.printStackTrace();
        catch (BadPaddingException badPadding)
             badPadding.printStackTrace();
        catch (IllegalBlockSizeException illegalBlockSize)
             illegalBlockSize.printStackTrace();
        catch (InvalidAlgorithmParameterException invalidParam)
             invalidParam.printStackTrace();
        catch (IOException e)
            e.printStackTrace();
        return strDecryptedText;
} I just want to have a method like boolean isAESEncrypted(String data){ ????  } in my class.
Could anybody give a helping hand for the same?
Many thanks in advance
Edited by: jagabandhu on Sep 16, 2010 10:54 AM

Answer 1

jagabandhu wrote:
I do have a choice to store the encrypted data only in 'varchar' format so I have to encrypt and store the password without changing the column data type in the database!
Again many thanks for 'Notes:' these are definitely helpful.
sabre150 wrote:
If you have a choice, then you should add a digest of the cleartext to the ciphertext. ...I fear if I use any MessageDigest , my password will be byte[] instead present String format.Not relevant since you Base64 encode the ciphertext you can also Base64 encode the digest!
for e.g.
[http://gmailassistant.sourceforge.net/src/org/freeshell/zs/common/Encryptor.java.html]
Could you please further guide me if I am in the right track?I thought I had guided you! I have pointed out what I see as the flaws in your code and I think you should use the more normal approach of just using a randomly seeded Message Digest.
>
FYI : I do not need a serious encryption format as per the present requirement. :)That is not serious encryption since it has at least 3 major security flaws.
>
Edited by: jagabandhu on Sep 16, 2010 1:17 PM