CODEWITHSUNDEEP
c#phptripledes
staskus
staskus

Reputation: 171

String Encrypted in C# Using TripleDES, need to decrypt in PHP

C# Code looks like that (can't change it as it's in a client's system).

namespace Common {
public static class EncryptionHelper
{

   private const string cryptoKey = "password";

// The Initialization Vector for the DES encryption routine
   private static readonly byte[] IV = new byte[8] { 240, 3, 45, 29, 0, 76, 173, 59 };

/// <summary>
/// Encrypts provided string parameter
/// </summary>
public static string Encrypt(string s)
{

   string result = string.Empty;

   byte[] buffer = Encoding.ASCII.GetBytes(s);

   byte[] k = Encoding.ASCII.GetBytes(cryptoKey);

   TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
   MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();


   des.Key = MD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(cryptoKey));

   des.IV = IV;

   result = Convert.ToBase64String(des.CreateEncryptor().TransformFinalBlock(buffer, 0, buffer.Length));

   return result;
  }
}
}

I found client took this class from here: http://johnnycoder.com/blog/2008/07/03/c-encryption-decryption-helper-class/

I'm not very familiar with C# and I need to Decrypt string in PHP encrypted with this code.

When I do "md5($key, true)" I don't get the same result as "MD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(cryptoKey));", not sure why.

How to convert "byte[] IV" to PHP string ?

Any help would be appreciated. Thank you.

Upvotes: 4

Views: 775

Answers (1)

staskus
staskus

Reputation: 171

Managed to get it working:

class Crypter
{

/**
 *
 * Encryption key
 *
 * @var
 */
protected $key;

/**
 *
 * Encryption vector
 *
 * @var
 */
protected $iv;

public function __construct()
{

    $this->key = config('auth.triple_des_key');
    $this->iv = implode(array_map("chr", config('auth.triple_des_iv')));
}


/**
 *
 * Decrypts string using tripleDES method.
 *
 * @param $input String
 * @return String
 */
public function decryptTripleDES($input)
{

    $td = mcrypt_module_open(MCRYPT_3DES, '', MCRYPT_MODE_CBC, '');

    $encryptedData = base64_decode($input);

    $key = iconv('utf-8', 'us-ascii//TRANSLIT', $this->key);

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

    mcrypt_generic_init($td, $key, $this->iv);

    $decryptedData = mdecrypt_generic($td, $encryptedData);
    mcrypt_generic_deinit($td);

    //remove the padding text
    $block = mcrypt_get_block_size("tripledes", "cbc");

    $packing = ord($decryptedData{strlen($decryptedData) - 1});

    if ($packing and ($packing < $block)) {
        for ($P = strlen($decryptedData) - 1; $P >= strlen($decryptedData) - $packing; $P--) {
          if (ord($decryptedData[$P]) != $packing) {
              $packing = 0;
          }
      }
    }

    $decryptedData = substr($decryptedData, 0, strlen($decryptedData) - $packing);

    return $decryptedData;
}
}

Upvotes: 3

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