Re: Using encryption with special Unicode characters

Mayeul <>
Mon, 29 Aug 2011 08:56:30 +0200
On 29/08/2011 08:11, Qu0ll wrote:

This is my first go at using Java encryption. I have a requirement to
encrypt and then later decrypt a series of strings that may contain
special Unicode characters such as "\u25bc". The code below correctly
encrypts and decrypts "normal" ASCII strings but turns characters like
"\u25bc" into '?' when it decrypts (or maybe even when it encrypts).

It doesn't really matter which encryption algorithm I use as long as it
is reasonably secure (I chose AES) but the encryption/decryption process
needs to handle these special characters.

The output from the following code is:

Before char(0): 9660
After char(0): 63
Equal: false

How can I get this to work? Here is the code:

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class Encryption {

private static final String ALGORITHM = "AES";

private static final String KEY = "0123456789ABCDEF";

private static final SecretKeySpec KEY_SPEC = new
SecretKeySpec(KEY.getBytes(), ALGORITHM);

private static Cipher cipherEncrypt;

private static Cipher cipherDecrypt;

static {
try {
cipherEncrypt = Cipher.getInstance(ALGORITHM);
cipherEncrypt.init(Cipher.ENCRYPT_MODE, KEY_SPEC);
cipherDecrypt = Cipher.getInstance(ALGORITHM);
cipherDecrypt.init(Cipher.DECRYPT_MODE, KEY_SPEC);
} catch (final Exception e) {

public static String decrypt(final byte[] raw) {
String result = null;
try {
result = new String(cipherDecrypt.doFinal(raw));
} catch (final Exception e) {

return result;

public static byte[] encrypt(final String raw) {
byte[] result = null;
try {
result = cipherEncrypt.doFinal(raw.getBytes());
} catch (final Exception e) {

return result;

public static void main(final String[] args) {
final String before = "\u25bc ABC";
System.out.println("Before char(0): " + (int)before.charAt(0));
final String after = decrypt(encrypt(before));
System.out.println("After char(0): " + (int)after.charAt(0));
System.out.println("Equal: " + before.equals(after));

String.getBytes() and String(byte[]), converting String to byte array
and backwise, is the job of a character encoding, which, in Java, are
called 'charsets'. If you do not specify which charset you want to use,
they will use your default charset, which depends on your environment.

This charset is not guaranteed to support Unicode. In fact, in western
environments it is rather likely to be iso-8859-1 or likewise, which
does not support Unicode.

Which is why you're better off forcing the use of a Unicode-compliant
charset, like utf-8. utf-8 and the utf-16s are guaranteed to be
supported by Java, which makes them safe choices.


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