用经Java加密的PHP中的DES解密字符串

Question

I've been banging my head against the wall trying to figure out exactly how to format everything to decrypt this string in PHP that's been encrypted in a custom Java class.

Here's the relevent functions from the Java class. The "salt" variable is a class variable byte array set earlier:

public DesEncrypter(String passPhrase) {
    try {
        // Create the key
        KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt,
                iterationCount);
        SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES")
                .generateSecret(keySpec);
        ecipher = Cipher.getInstance(key.getAlgorithm());
        dcipher = Cipher.getInstance(key.getAlgorithm());

        // Prepare the parameter to the ciphers
        AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt,
                iterationCount);

        // Create the ciphers
        ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
        dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
    } catch (java.security.InvalidAlgorithmParameterException e) {
    } catch (java.security.spec.InvalidKeySpecException e) {
    } catch (javax.crypto.NoSuchPaddingException e) {
    } catch (java.security.NoSuchAlgorithmException e) {
    } catch (java.security.InvalidKeyException e) {
    }
}

public String encrypt(String str) {
    try {
        // Encode the string into bytes using utf-8
        byte[] utf8 = str.getBytes("UTF8");

        // Encrypt
        byte[] enc = ecipher.doFinal(utf8);

        // Encode bytes to base64 to get a string
        return new sun.misc.BASE64Encoder().encode(enc);
    } catch (javax.crypto.BadPaddingException e) {
    } catch (IllegalBlockSizeException e) {
    } catch (UnsupportedEncodingException e) {
    }
    return null;
}

public String decrypt(String str) {
    try {
        // Decode base64 to get bytes
        byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

        // Decrypt
        byte[] utf8 = dcipher.doFinal(dec);

        // Decode using utf-8
        return new String(utf8, "UTF8");
    } catch( Exception ex) {
        ex.printStackTrace(System.err);
    }
    return null;
}

And here's what I have so far in PHP (FYI, I'm using this encryption library in PHP https://github.com/phpseclib/phpseclib ):

$app->get('/decrypt', function () use ($app) {
    $data = '3aCRLRd3srA/QF4MQb0D+P==';
    $salt = pack('nvc*', 0xB7, 0x9A, 0xC1, 0x34, 0x26, 0x89, 0xW3, 0x30);
    $secret = "secret";
    $keyLength = 16;

    $cipher = new Crypt_DES(CRYPT_DES_MODE_CBC);
    $cipher->setPassword($secret, 'pbkdf2', 'md5', $salt, $keyLength);

    var_dump($cipher->decrypt($data));
});

Right now it's dumping out a bunch of binary, which I've tried base64_decoding, but that doesn't do anything either.

Answer 1

If key.getAlgorithm() is "DES" then you need to provide a fully specified Cipher name like "DES/CBC/PKCS5Padding".

You will also need to provide the IV if it is non-null. Usually the IV is prepended to the ciphertext.

You can get the IV with cipher.getIV() and set with $cipher->setIV('...'); .