Java AES / CFB8 / NoPadding加密和Charset

Question

I'm trying to encrypt and decrypt Strings in Java and PHP, so i use AES/CFB8/NoPadding that sould work on both sides.

Now my Cryptor works quit well with Latin Characters, as long as i set the Charset to Latin. But when i set it to UTF-8 (which is what i use in my DB), the encryption is not properly done.

Here is the output:

/*
* Latin (ISO-8859-1) output:
* Original: MiiiMüäöMeeʞ
* Encoded: rQ¶[ÉÐRíD
* Decoded: MiiiMüäöMee?
* 
* UTF-8 output:
* Original: MiiiMüäöMeeʞ
* Encoded: rQ�[�
* Decoded: Mii0SS1])_�ELJI�S�;�W��W?*
*/

Since "ʞ" is not a latin character, I understand it can not be encrypted properly. But why does UTF-8 not work?

public class Cryptor {

    private Cipher cipher;
    private String secretKey = "1234567890qwertz";
    private String iv = "1234567890qwertz";

    private SecretKey keySpec;
    private IvParameterSpec ivSpec;
    private Charset CHARSET = Charset.forName("ISO-8859-1"); // ISO-8859-1 vs. UTF-8

    public Cryptor() throws CryptingException {

        keySpec = new SecretKeySpec(secretKey.getBytes(CHARSET), "AES");
        ivSpec = new IvParameterSpec(iv.getBytes(CHARSET));
        try {
            cipher = Cipher.getInstance("AES/CFB8/NoPadding");
        } catch (NoSuchAlgorithmException e) {
            throw new SecurityException(e);
        } catch (NoSuchPaddingException e) {
            throw new SecurityException(e);
        }
    }

    public String decrypt(String input) throws CryptingException {

        try {
            cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
            return new String(cipher.doFinal(input.getBytes(CHARSET)), CHARSET).trim();
        } catch (IllegalBlockSizeException e) {
            throw new SecurityException(e);
        } catch (BadPaddingException e) {
            throw new SecurityException(e);
        } catch (InvalidKeyException e) {
            throw new SecurityException(e);
        } catch (InvalidAlgorithmParameterException e) {
            throw new SecurityException(e);
        }
    }

    public String encrypt(String input) throws CryptingException {
        try {
            cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);
            return new String(cipher.doFinal(input.getBytes(CHARSET)), CHARSET).trim();
        } catch (InvalidKeyException e) {
            throw new SecurityException(e);
        } catch (InvalidAlgorithmParameterException e) {
            throw new SecurityException(e);
        } catch (IllegalBlockSizeException e) {
            throw new SecurityException(e);
        } catch (BadPaddingException e) {
            throw new SecurityException(e);
        }
    }

    public static void main(String Args[]) {

        try {
            Cryptor c = new Cryptor();
            String original = "MiiiMüäöMeeʞ";
            System.out.println("Original: " + original);
            String encrypted = c.encrypt("MiiiMüäöMeeʞ");
            System.out.println("Encoded: " + encrypted);
            System.out.println("Decoded: " + c.decrypt(encrypted));

        } catch (CryptingException e) {
            e.printStackTrace();
        }
    }

    class CryptingException extends RuntimeException {

        private static final long serialVersionUID = 7123322995084333687L;

        public CryptingException() {
            super();
        }

        public CryptingException(String message) {
            super(message);
        }
    }
}

Answer 1

I think turning the encrypted bytes into a String is a bad idea. The bytes are not valid for any encoding, they are random.

You need to encode the resulting byte[] to base64 to get a consistent outcome. See sun.misc.BASE64Encoder / sun.misc.BASE64Decoder .

Here is an example of decoding a base64 String to a byte[] , the reverse process is very similar.

You can declare the decoder/encoder and the top of the class:

private final BASE64Decoder base64Decoder = new BASE64Decoder();
private final BASE64Encoder base64Encoder = new BASE64Encoder();

Then in your decypt method you need to call

return new String(cipher.doFinal(base64Decoder.decodeBuffer(input)), CHARSET);

And in your encrypt method

return base64Encoder.encode(cipher.doFinal(input.getBytes(CHARSET)));

Output using UTF-8:

Original: MiiiMüäöMeeʞ
Encoded: clEUtlv2ALXsKYw4ivOfwQ==
Decoded: MiiiMüäöMeeʞ

One side note is that it's not strictly speaking good practice to use packages from sun.* as they are not part of the java spec and hence may change/vanish from version to version.

Here is a little article on moving to the Apache Commons Codec implementation.
This is also a similar class in the Guava API.

Answer 2

Thanks alot for that answer, it really helped me alot.

Here is the working code i use to encrypt and decrypt JSON stuff in JAVA and PHP:

 /*-- JAVA --*/ /** * Is used for encrypting and decrypting Strings and JSONObjects. <br> * The JSON Objects can then be sent to a PHP script where they can be encrypted and decrypted with the same algorithm. * @throws CryptingException */ public class Cryptor { private Cipher cipher; private String secretKey = "1234567890qwertz"; private String iv = "1234567890qwertz"; private final String CIPHER_MODE = "AES/CFB8/NoPadding"; private SecretKey keySpec; private IvParameterSpec ivSpec; private Charset CHARSET = Charset.forName("UTF8"); public Cryptor() throws CryptingException { keySpec = new SecretKeySpec(secretKey.getBytes(CHARSET), "AES"); ivSpec = new IvParameterSpec(iv.getBytes(CHARSET)); try { cipher = Cipher.getInstance(CIPHER_MODE); } catch (NoSuchAlgorithmException e) { throw new SecurityException(e); } catch (NoSuchPaddingException e) { throw new SecurityException(e); } } /** * @param input A "AES/CFB8/NoPadding" encrypted String * @return The decrypted String * @throws CryptingException */ public String decrypt(String input) throws CryptingException { try { cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec); return new String(cipher.doFinal(DatatypeConverter.parseBase64Binary(input))); } catch (IllegalBlockSizeException e) { throw new SecurityException(e); } catch (BadPaddingException e) { throw new SecurityException(e); } catch (InvalidKeyException e) { throw new SecurityException(e); } catch (InvalidAlgorithmParameterException e) { throw new SecurityException(e); } } /** * @param input Any String to be encrypted * @return An "AES/CFB8/NoPadding" encrypted String * @throws CryptingException */ public String encrypt(String input) throws CryptingException { try { cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec); return DatatypeConverter.printBase64Binary(cipher.doFinal(input.getBytes(CHARSET))).trim(); } catch (InvalidKeyException e) { throw new SecurityException(e); } catch (InvalidAlgorithmParameterException e) { throw new SecurityException(e); } catch (IllegalBlockSizeException e) { throw new SecurityException(e); } catch (BadPaddingException e) { throw new SecurityException(e); } } /** * Encrypts the keys and values of a JSONObject with Cryptor.encrypt(String input) * @param o The JSONObject to be encrypted * @return A JSONObject with encrypted keys and values */ public JSONObject jsonObjectEncrypt(JSONObject o) { Iterator<?> keys = o.keys(); JSONObject returnObject = new JSONObject(); while( keys.hasNext() ){ String key = (String)keys.next(); returnObject.put(this.encrypt(key), this.encrypt(o.getString(key))); } return returnObject; } /** * Decrypts the keys and values of a JSONObject with Cryptor.decrypt(String input) * @param o The JSONObject to be decrypted * @return A JSONObject with decrypted keys and values */ public JSONObject jsonObjectDecrypt(JSONObject o) { Iterator<?> keys = o.keys(); JSONObject returnObject = new JSONObject(); while( keys.hasNext() ){ String key = (String)keys.next(); if(key != null && !key.equals("")) { returnObject.put(this.decrypt(key), this.decrypt(o.getString(key))); } } return returnObject; } /** * Encrypts keys and values of every JSONObject in a JSONArray * @param a The JSONArray to be encrypted * @return A JSONArray with encrypted keys and values */ public JSONArray jsonArrayEncrypt(JSONArray a) { JSONArray returnArray = new JSONArray(); for(int i = 0; i < a.length(); i++) { returnArray.put(this.jsonObjectEncrypt((JSONObject)a.get(i))); } return returnArray; } /** * Decrypts keys and values of every JSONObject in a JSONArray * @param a The JSONArray to be decrypted * @return A JSONArray with decrypted keys and values */ public JSONArray jsonArrayDecrypt(JSONArray a) { JSONArray returnArray = new JSONArray(); for(int i = 0; i < a.length(); i++) { returnArray.put(this.jsonObjectDecrypt((JSONObject)a.get(i))); } return returnArray; } public static void main(String Args[]) { try { Cryptor c = new Cryptor(); String original = "MiiiMüäöMeeʞ"; System.out.println("Original: " + original); String encrypted = c.encrypt(original); System.out.println("Encoded: " + encrypted); System.out.println("Decoded: " + c.decrypt(encrypted)); JSONArray arr = new JSONArray("[{\\"id\\"=\\" 1 ʞ3 \\"},{\\"id\\"=\\"4\\"}]"); System.out.println(c.jsonArrayDecrypt(c.jsonArrayEncrypt(arr)).getJSONObject(0).getString("id")); } catch (CryptingException e) { e.printStackTrace(); } } } /*-- PHP ---*/ <html> <meta charset='utf-8'> <?php $cryptor = new Cryptor(); echo $cryptor->decrypt($cryptor->encrypt("MiiiMüäöMeeʞ")); class Cryptor { //Use same as in java Cryptor private $iv = '1234567890qwertz'; private $secretKey = '1234567890qwertz'; function encrypt($input) { return base64_encode( mcrypt_encrypt( MCRYPT_RIJNDAEL_128, $this->secretKey, $input, MCRYPT_MODE_CFB, $this->iv ) ); } function decrypt($input) { return mcrypt_decrypt( MCRYPT_RIJNDAEL_128, $this->secretKey, base64_decode($input), MCRYPT_MODE_CFB, $this->iv ); } function arrayDecrypt($array) { $returnArray = array(); foreach($array as $key=>$value) { $newKey = $this->decrypt($key); $returnArray[$newKey] = $this->decrypt($value); } return $returnArray; } function arrayEncrypt($array) { $returnArray = array(); foreach($array as $key=>$value) { $returnArray[$this->encrypt($key)] = $this->encrypt($value); } return $returnArray; } } ?> </html>