如何像在Java上的代码一样在php上加密字符串？

Question

For a project I should encrypt strings on php as same as a code block on java side. Below there is the java code. "input" is the string to be encrypted and "key" encryption key.

    MessageDigest digest;
    try {
        digest = MessageDigest.getInstance("MD5");
        byte[] md5key = digest.digest(key.getBytes("UTF-8"));
        Cipher cipher = Cipher.getInstance("DESEDE/ECB/PKCS5Padding");
        SecretKeySpec myKey = new SecretKeySpec(md5key, "DESede");
        cipher.init(Cipher.ENCRYPT_MODE, myKey);

        try {
            byte[] encryptedPlainText = cipher.doFinal(input.getBytes());

            String encrypted = Base64.encodeToString(encryptedPlainText, 0);
            return encrypted;

        }
    }

And here is the php code that I tried to encrypt strings. "encryptText_3des" function gets the string and the key, and returns encrypted string.

function encryptText_3des($plainText, $key) {
    $key = hash("md5", $key, true);
    $padded = pkcs5_pad($plainText, mcrypt_get_block_size(MCRYPT_3DES, MCRYPT_MODE_ECB));
    $encrypted = base64_encode(mcrypt_encrypt(MCRYPT_3DES, $key, $padded, MCRYPT_MODE_ECB));
    return $encrypted;
}

function pkcs5_pad ($text, $blocksize) 
{ 
    $pad = $blocksize - (strlen($text) % $blocksize); 
    return $text . str_repeat(chr($pad), $pad); 
}

The output strings of java and php codes are not same. What the point that I am missing?

Thanks...

Answer 1

The problem is that PHP seems to use it's own proprietary key extension mechanism. Instead of using the 16 bytes as DES ABA key (16 bytes) it simply extends the key with 0 valued characters until it has 24 bytes to use as DES ABC key.

If you want to have DES EDE with 16 bytes key, then you should repeat the first 8 bytes of your key (retrieved from MD5) at the end of your key:

$key = hash("md5", $key, true);
$key = $key . substr($key, 0, 8);