Question

Possible Duplicate:
InvalidKeyException Illegal key size

public static byte[] encryptBytes(byte[] bytes, byte[] key)
{
    Cipher cipher = null;

    try
    {
        cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        SecretKeySpec secretKey = new SecretKeySpec(key, "AES");
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);

        return Base64.encodeBase64(cipher.doFinal(bytes));
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }

    return null;
}

public static byte[] decrpytBytes(byte[] encryptedData, String key)
{
    byte[] keyBytes = convertToByteArray(key);
    Cipher cipher = null;

    try
    {
        cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
        SecretKeySpec secretKey = new SecretKeySpec(keyBytes, "AES");
        cipher.init(Cipher.DECRYPT_MODE, secretKey);

        return cipher.doFinal(Base64.decodeBase64(encryptedData));
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }

    return null;
}
//Simply takes every other two characters an terms them into a byte value 
    //then stuffs them into  a byteArray
public static byte[] convertToByteArray(String key)
{
    byte[] b = new byte[key.length()/2];

    for(int i=0, bStepper=0; i<key.length()+2; i+=2)
        if(i !=0)
            b[bStepper++]=((byte) Integer.parseInt((key.charAt(i-2)+""+key.charAt(i-1)), 16));

    return b;
}

public static void main(String[] args) throws Exception
{
            //This string has 64 characters. When sent to convertToByteArray it returns a byte array or 32 bytes
    String key = "00112233445566778899AABBCCDDEEFF0123456789ABCDEF0123456789ABCDEF";

            //Test it out
    byte f[] = {2,4,7};
    byte[] encrypted = encryptBytes(f, convertToByteArray(key));
    byte[] unencrypted = decrpytBytes(encrypted, key);

    System.out.print(unencrypted[0]);
}

Error:

Illegal key size or default parameters

I dont know why I’m getting an invalid key size. It should be able to take 32 byte key with 256 encryption

Answer 1

http://www.javamex.com/tutorials/cryptography/unrestricted_policy_files.shtml

“It turns out that the Cipher class will generally not allow encryption with a key size of more than 128 bits. The apparent reason behind this is that some countries (although increasingly fewer) have restrictions on the permitted key strength of imported encryption software, although the actual number 128 is questionable (see below). The good news is that:

You can easily remove the restriction by overriding the security policy files with others that Sun provides.”