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Jon Skeet
Java AES not decrypting Arabic
I'm working on Eclipse to encrypt and decrypt a string. I'm using the following functions:
private final static String ALGORITHM = "AES";
public static String cipher(String secretKey, String data) throws Exception {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), secretKey.getBytes(), 128, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey key = new SecretKeySpec(tmp.getEncoded(), ALGORITHM);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, key);
return toHex(cipher.doFinal(data.getBytes()));
}
public static String decipher(String secretKey, String data) throws Exception {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), secretKey.getBytes(), 128, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey key = new SecretKeySpec(tmp.getEncoded(), ALGORITHM);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, key);
return new String(cipher.doFinal(toByte(data)));
}
private static byte[] toByte(String hexString) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
return result;
}
public static String toHex(byte[] stringBytes) {
StringBuffer result = new StringBuffer(2*stringBytes.length);
for (int i = 0; i < stringBytes.length; i++) {
result.append(HEX.charAt((stringBytes[i]>>4)&0x0f)).append(HEX.charAt(stringBytes[i]&0x0f));
}
return result.toString();
}
private final static String HEX = "0123456789ABCDEF";
The string that I'm working on contains English and Arabic characters. When I'm decrypting the string, the arabic characters are replaced by a question mark ( ? )
How can I solve this problem ?
There are three separate transformations here:
- Unencrypted text to unencrypted bytes
- Unencrypted bytes to encrypted bytes
- Encrypted bytes to hex
... and the reverse, of course.
I suspect the problem is in the first step. Currently you're using new String(byte[]) and String.getBytes(), both of which use the platform default encoding. That's almost always a bad idea. It's generally a good idea to use UTF-8 (e.g. using StandardCharsets.UTF_8) for all encoding and decoding, unless you have a good reason to use something else.
That's one starting point - but another is to look at each of those transformations separately, and work out where the data is being broken. Lots of diagnostics will help here.
I have a blog post about precisely this sort of problem, which goes into more detail.
See more on this question at Stackoverflow