解密（使用PHP）Java加密（PBEWithMD5AndDES）

Question

I need your help. I was asked to decrypt strings via PHP, starting by this java class:

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

import com.sun.mail.util.BASE64DecoderStream;

public class Decryptor {

    private Cipher dcipher;

    private static final int iterationCount = 10;

    private static byte[] salt = {
        (byte) 0xB2, (byte) 0x12, (byte) 0xD5, (byte) 0xB2,
        (byte) 0x44, (byte) 0x21, (byte) 0xC3, (byte) 0xC3 };

    Decryptor(String passPhrase) {
        try {
            KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount);
            SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
            AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
            dcipher = Cipher.getInstance(key.getAlgorithm());
            dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
        } catch (InvalidAlgorithmParameterException e) {
            e.printStackTrace();
        } catch (InvalidKeySpecException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        }
    }

    public String decrypt(String str) {
        try {
            byte[] dec = BASE64DecoderStream.decode(str.getBytes());
            byte[] utf8 = dcipher.doFinal(dec);
            return new String(utf8, "UTF8");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;

    }

}

I don't know the Java language so I need some help to understand this encryption.

I tried to use this code: https://github.com/KevinBusse/PBEWithMD5AndDES

But I can't "translate" the salt to PHP string and it doesn't seem to work.

Thank you!

Answer 1

Try something like this, It worked for me.

Take your salt:

$bytes = array ( 0xB9,  0x2B, 0xC8,  0x32, 0x56,  0x35 ,  0xE3, 0x03 );

Convert it to String in php :

$salt = call_user_func_array(
    'sprintf',
    array_merge((array) str_repeat('%c', count($bytes)), $bytes)
);

Goto this repo: https://github.com/KevinBusse/PBEWithMD5AndDES

Goto class PkcsKeyGenerator and comment this code $salt = pack('H*', $salt); like this.

function __construct($keystring, $salt, $iterationsMd5, $segments)
    {
       // $salt = pack('H*', $salt);
        $keyMaterial = '';
        $data = $keystring . $salt;
        $result = '';
        for ($j = 0; $j < $segments; $j++)
        {
            if ($j == 0)
            {
                $result = $data;
            }
            else
            {
                $result .= $data;
            }
            for ($i = 0; $i < $iterationsMd5; $i++)
            {
                $result = md5($result, true);
            }
            $keyMaterial .= $result;
        }
        $this->_key = substr($keyMaterial, 0, 8);
        $this->_iv = substr($keyMaterial, 8, 8);
    }

Now try.