将PHP加密和解密方法转换为Java

Question

I tried to convert the encrypt and decrypt functions to use in Java for the below PHP. But received illegal key size error. Suggest me to do 256bit AES decryption in java.

PHP Code

<?php
    function encrypt ($data,$salt) {
        $hash = base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, md5($salt), $data, MCRYPT_MODE_CBC, md5(md5($salt))));
        return $hash;
    }
    function decrypt ($encdata,$salt) {
        $string = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, md5($salt), base64_decode($encdata), MCRYPT_MODE_CBC, md5(md5($salt)));
        return $string;
    }
?>

Converted Java Code:

//The below code found in http://www.logikdev.com/2010/11/01/encrypt-with-php-decrypt-with-java/
    public static String md5(String input) throws NoSuchAlgorithmException {
        MessageDigest md = MessageDigest.getInstance("MD5");
        byte[] messageDigest = md.digest(input.getBytes());
        BigInteger number = new BigInteger(1, messageDigest);
        return number.toString(16);
    }

    public String decrypt(String encryptedData) {
        String decryptedData = null;
        try {
            SecretKeySpec skeySpec = new SecretKeySpec(md5("5A17K3Y").getBytes(), "AES");           
            String initialVectorString=md5(md5("5A17K3Y"));
            IvParameterSpec initialVector = new IvParameterSpec(initialVectorString.getBytes());
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding","SunJCE");            
            cipher.init(Cipher.DECRYPT_MODE, skeySpec, initialVector);          
            encryptedData=encryptedData.replace('-','+').replace('_','/').replace(',','=');
            byte[] encryptedByteArray = (new org.apache.commons.codec.binary.Base64()).decode((encryptedData.getBytes()));          
            byte[] decryptedByteArray = cipher.doFinal(encryptedByteArray);
            decryptedData = new String(decryptedByteArray, "UTF8");
        } catch (Exception e) {         
            System.out.println("Error. Problem decrypting the data: " + e);
        }
    }

Problem decrypting the data: java.security.InvalidKeyException: Illegal key size

Answer 1

You receive an illegal key size error when you've not installed the unlimited strength jurisdiction files. These files permit Java to use stronger key lengths (for example 256-bit AES).

Go to the Oracle download site and hunt for the files that match your Java version. If it is legal in your country to do so, install these files and enjoy stronger crypto.

( Side note: did you research this at all? The first upteem results would have answered your issue ).