CODEWITHSUNDEEP
.netphpencryption
Graviton
Graviton

Reputation: 83244

MCRYPT in .Net

I have a PHP decryption algorithm at one end, and a .Net encryption algorithm at another. I am using mcrypt_decrypt for decrypt purpose in PHP code, and looking for an equivalent of mcrypt_encrypt in .Net. More specifically, the PHP code that I want to convert to .Net is the following:

$cipher_alg = MCRYPT_RIJNDAEL_128;
$iv = mcrypt_create_iv ( mcrypt_get_iv_size ( $cipher_alg, MCRYPT_MODE_ECB ), MCRYPT_RAND );

$encrypted_string = mcrypt_encrypt ( $cipher_alg, $sessionkey, $string, MCRYPT_MODE_CBC, $iv );
$hex_encrypted_string = bin2hex ( $encrypted_string );

Is there an equivalent of mcrypt_encrypt in .Net?

Upvotes: 2

Views: 2324

Answers (2)

Graviton
Graviton

Reputation: 83244

I have come out with a solution in my blog.

Here is an excerpt :

    private static string CreateEncryptedString(string myString, string hexiv, string key)
    {
        RijndaelManaged alg = new RijndaelManaged();
        alg.Padding = PaddingMode.Zeros;
        alg.Mode = CipherMode.CBC;
        alg.BlockSize = 16 * 8;
        alg.Key = ASCIIEncoding.UTF8.GetBytes(key);
        alg.IV = StringToByteArray(hexiv);
        ICryptoTransform encryptor = alg.CreateEncryptor(alg.Key, alg.IV);

        MemoryStream msStream = new MemoryStream();
        CryptoStream mCSWriter = new CryptoStream(msStream, encryptor, CryptoStreamMode.Write);
        StreamWriter mSWriter = new StreamWriter(mCSWriter);
        mSWriter.Write(myString);
        mSWriter.Flush();
        mCSWriter.FlushFinalBlock();

        var EncryptedByte = new byte[msStream.Length];
        msStream.Position = 0;
        msStream.Read(EncryptedByte, 0, (int)msStream.Length);

        return ByteArrayToHexString(EncryptedByte);

    }

    public static byte[] StringToByteArray(String hex)
    {
        int NumberChars = hex.Length;
        byte[] bytes = new byte[NumberChars / 2];
        for (int i = 0; i < NumberChars; i += 2)
            bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);
        return bytes;
    }

    public static string ByteArrayToHexString(byte[] ba)
    {
        StringBuilder hex = new StringBuilder(ba.Length * 2);
        foreach (byte b in ba)
            hex.AppendFormat("{0:x2}", b);
        return hex.ToString();
    }

There is one thing to note. The key size must be 16. Which means that key parameter must be a string with 16 characters. Or else the encryption won't work and will throw a CryptographicException.

On the PHP end, here's how you do the decoding:

$cipher_alg = MCRYPT_RIJNDAEL_128;
$decrypted_string = mcrypt_decrypt($cipher_alg, $key, 
$encrypted_string , MCRYPT_MODE_CBC, trim(hex2bin(trim($hexiv))));

Upvotes: 3

Jon Skeet
Jon Skeet

Reputation: 1499660

There isn't a direct equivalent, but 128-bit Rijndael is supported (and probably most other ciphers that you would want). See the Rijndael class for details and an example.

Basically the encryption part of the framework is based on you specifying an appropriate instance of a base class (CryptoStream, SymmetricAlgorithm etc) rather than specifying a cipher by name - but you should be able to do what you need to.

Upvotes: 1

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