Encryption Between PHP & Java

Question

I was looking to encrypt data between a PHP server and a Java Client. Individually the code works fine and I would like to stick with OpenSSL on the PHP server.

Do any of you see anything that I am missing here as I get an error when trying to decode the PHP encrypted string:

PHP:

<?php

$iv = 'fedcba9876543210'; #Same as in JAVA
$key = '0123456789abcdef'; #Same as in JAVA



$ciphers = openssl_get_cipher_methods(FALSE);
$ciphers_and_aliases = openssl_get_cipher_methods(true);
$cipher_aliases = array_diff($ciphers_and_aliases, $ciphers);

print_r($ciphers);

//print_r($cipher_aliases);


// DEFINE our cipher
define('AES_CBC', 'aes-128-cbc');
// Generate a 256-bit encryption key
// This should be stored somewhere instead of recreating it each time
$encryption_key = "test_key";
// Generate an initialization vector
// This *MUST* be available for decryption as well
//$iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length(AES_CBC));

// Create some data to encrypt
$data = "Hello World!!!";
$data_b64= base64_encode($data);
echo "Before encryption: $data<br><br>Before Base64: $data_b64<br><br>";
// Encrypt $data using aes-256-cbc cipher with the given encryption key and
// our initialization vector. The 0 gives us the default options, but can
// be changed to OPENSSL_RAW_DATA or OPENSSL_ZERO_PADDING
$encrypted = openssl_encrypt($data_b64, AES_CBC, $encryption_key, 0, $iv);
$len = strlen($encrypted);
echo "Encrypted Len: $len  <br><br>";
$encrypted64 = base64_encode($encrypted);
echo "Encrypted b64: $encrypted64<br><br>";
// If we lose the $iv variable, we can't decrypt this, so:
// - $encrypted is already base64-encoded from openssl_encrypt
// - Append a separator that we know won't exist in base64, ":"
// - And then append a base64-encoded $iv
$encrypted = $encrypted64 . ':' . base64_encode($iv);
echo "Encrypted: $encrypted<br><br>";
// To decrypt, separate the encrypted data from the initialization vector ($iv).
$parts = explode(':', $encrypted);
// $parts[0] = encrypted data
// $parts[1] = base-64 encoded initialization vector
// Don't forget to base64-decode the $iv before feeding it back to
//openssl_decrypt
$decrypted64 = openssl_decrypt(base64_decode($parts[0]), AES_CBC, $encryption_key, 0, base64_decode($parts[1]));
$decrypted = base64_decode($decrypted64);
echo "Decrypted: $decrypted\n";
?>

PHP output:

Before encryption: Hello World!!!

Before Base64: SGVsbG8gV29ybGQhISE=

Encrypted Len: 44

Encrypted b64: U21yMVRGQTdROVc3TWJ1Wm1HUTBhMmZmenlIN2tvdWQ5SHA5ekVxUmp5az0=

Encrypted: U21yMVRGQTdROVc3TWJ1Wm1HUTBhMmZmenlIN2tvdWQ5SHA5ekVxUmp5az0=:ZmVkY2JhOTg3NjU0MzIxMA==

Decrypted: Hello World!!!

Java Code:

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

import java.util.Base64;
import java.security.*;

public class Sandbox {

    public static String encrypt(String key, String initVector, String value) {
        try {
            IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");

            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);

            byte[] encrypted = cipher.doFinal(Base64.getEncoder().encode(value.getBytes()));
            System.out.println("encrypted string: "
                    + Base64.getEncoder().encodeToString(encrypted));

            return Base64.getEncoder().encodeToString(encrypted);
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

    public static String decrypt(String key, String initVector, String encrypted) {
        try {
            IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");


            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);

            byte[] temp = Base64.getDecoder().decode(encrypted);

            System.out.println((new String(temp)).length());
            byte[] original = cipher.doFinal(temp);
            original = Base64.getDecoder().decode(original);

            return new String(original);
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

    public static void main(String[] args) {
        String key = "0123456789abcdef"; // 128 bit key
        String initVector = "fedcba9876543210"; // 16 bytes IV

//        for (Provider provider : Security.getProviders()) {
//            System.out.println(provider.getName());
//            for (String key2 : provider.stringPropertyNames()) {
//                System.out.println("\t" + key2 + "\t" + provider.getProperty(key2));
//            }
//        }
        System.out.println(decrypt(key, initVector,
                encrypt(key, initVector, "Hello World!!!")));

        System.out.println(decrypt(key, initVector, "R090NDcvclAyY2E1cmxLWG9kSGlnUktHdEI5U05sRGxNdWF4NFFjUUV0OD0="));
    }
}

Java Output:

> 
30
Hello World!!!

44

null

javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher
    at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:913)
    at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:824)
    at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:436)
    at javax.crypto.Cipher.doFinal(Cipher.java:2165)
    at Sandbox.decrypt(Sandbox.java:43)
    at Sandbox.main(Sandbox.java:67)
BUILD SUCCESSFUL (total time: 1 second)

Answer 1

A working version can be found - https://github.com/chaudhuri-ab/CrossPlatformCiphers

Some things to keep in mind is the that if you do not specify OPENSSL_RAW_DATA in PHP the data will be encrypted as base64. That was throwing me off.

PHP:

class PHP_AES_Cipher {

    private static $OPENSSL_CIPHER_NAME = "aes-128-cbc"; //Name of OpenSSL Cipher 
    private static $CIPHER_KEY_LEN = 16; //128 bits

    /**
     * Encrypt data using AES Cipher (CBC) with 128 bit key
     * 
     * @param type $key - key to use should be 16 bytes long (128 bits)
     * @param type $iv - initialization vector
     * @param type $data - data to encrypt
     * @return encrypted data in base64 encoding with iv attached at end after a :
     */

    static function encrypt($key, $iv, $data) {
        if (strlen($key) < PHP_AES_Cipher::$CIPHER_KEY_LEN) {
            $key = str_pad("$key", PHP_AES_Cipher::$CIPHER_KEY_LEN, "0"); //0 pad to len 16
        } else if (strlen($key) > PHP_AES_Cipher::$CIPHER_KEY_LEN) {
            $key = substr($str, 0, PHP_AES_Cipher::$CIPHER_KEY_LEN); //truncate to 16 bytes
        }

        $encodedEncryptedData = base64_encode(openssl_encrypt($data, PHP_AES_Cipher::$OPENSSL_CIPHER_NAME, $key, OPENSSL_RAW_DATA, $iv));
        $encodedIV = base64_encode($iv);
        $encryptedPayload = $encodedEncryptedData.":".$encodedIV;

        return $encryptedPayload;

    }

    /**
     * Decrypt data using AES Cipher (CBC) with 128 bit key
     * 
     * @param type $key - key to use should be 16 bytes long (128 bits)
     * @param type $data - data to be decrypted in base64 encoding with iv attached at the end after a :
     * @return decrypted data
     */
    static function decrypt($key, $data) {
        if (strlen($key) < PHP_AES_Cipher::$CIPHER_KEY_LEN) {
            $key = str_pad("$key", PHP_AES_Cipher::$CIPHER_KEY_LEN, "0"); //0 pad to len 16
        } else if (strlen($key) > PHP_AES_Cipher::$CIPHER_KEY_LEN) {
            $key = substr($str, 0, PHP_AES_Cipher::$CIPHER_KEY_LEN); //truncate to 16 bytes
        }

        $parts = explode(':', $data); //Separate Encrypted data from iv.
        $decryptedData = openssl_decrypt(base64_decode($parts[0]), PHP_AES_Cipher::$OPENSSL_CIPHER_NAME, $key, OPENSSL_RAW_DATA, base64_decode($parts[1]));

        return $decryptedData;
    }

}

Java:

package ciphers;

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

import java.util.Base64;

public class Java_AES_Cipher {

    private static String CIPHER_NAME = "AES/CBC/PKCS5PADDING";
    private static int CIPHER_KEY_LEN = 16; //128 bits

    /**
     * Encrypt data using AES Cipher (CBC) with 128 bit key
     * 
     * 
     * @param key  - key to use should be 16 bytes long (128 bits)
     * @param iv - initialization vector
     * @param data - data to encrypt
     * @return encryptedData data in base64 encoding with iv attached at end after a :
     */
    public static String encrypt(String key, String iv, String data) {
        try {
            if (key.length() < Java_AES_Cipher.CIPHER_KEY_LEN) {
                int numPad = Java_AES_Cipher.CIPHER_KEY_LEN - key.length();

                for(int i = 0; i < numPad; i++){
                    key += "0"; //0 pad to len 16 bytes
                }

            } else if (key.length() > Java_AES_Cipher.CIPHER_KEY_LEN) {
                key = key.substring(0, CIPHER_KEY_LEN); //truncate to 16 bytes
            }


            IvParameterSpec initVector = new IvParameterSpec(iv.getBytes("UTF-8"));
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");

            Cipher cipher = Cipher.getInstance(Java_AES_Cipher.CIPHER_NAME);
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec, initVector);

            byte[] encryptedData = cipher.doFinal((data.getBytes()));

            String base64_EncryptedData = Base64.getEncoder().encodeToString(encryptedData);
            String base64_IV = Base64.getEncoder().encodeToString(iv.getBytes("UTF-8"));

            return base64_EncryptedData + ":" + base64_IV;

        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

    /**
     * Decrypt data using AES Cipher (CBC) with 128 bit key
     * 
     * @param key - key to use should be 16 bytes long (128 bits)
     * @param data - encrypted data with iv at the end separate by :
     * @return decrypted data string
     */

    public static String decrypt(String key, String data) {
        try {

            String[] parts = data.split(":");

            IvParameterSpec iv = new IvParameterSpec(Base64.getDecoder().decode(parts[1]));
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");

            Cipher cipher = Cipher.getInstance(Java_AES_Cipher.CIPHER_NAME);
            cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);

            byte[] decodedEncryptedData = Base64.getDecoder().decode(parts[0]);

            byte[] original = cipher.doFinal(decodedEncryptedData);

            return new String(original);
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

}