C# TripleDES ECB Encryption in PHP

Question

I mostly work with PHP, but I'm sending data to an api that's using C# for encryption, so I'm trying to encrypt a password in PHP, using the same method used in the following C# code:

System.Security.Cryptography.TripleDESCryptoServiceProvider DES = new System.Security.Cryptography.TripleDESCryptoServiceProvider(); System.Security.Cryptography.MD5CryptoServiceProvider hashMD5 = new System.Security.Cryptography.MD5CryptoServiceProvider(); DES.Key = hashMD5.ComputeHash(System.Text.ASCIIEncoding.ASCII.GetBytes(Key)); DES.Mode = System.Security.Cryptography.CipherMode.ECB; System.Security.Cryptography.ICryptoTransform DESEncrypt = DES.CreateEncryptor(); Buffer = System.Text.ASCIIEncoding.ASCII.GetBytes(Plaintext); string TripleDES = Convert.ToBase64String(DESEncrypt.TransformFinalBlock(Buffer, 0, Buffer.Length)); return TripleDES;

This is what I have so far in PHP:

 function encryptData($key, $plainText) { $byte = mb_convert_encoding($key, 'ASCII'); $desKey = md5(utf8_encode($byte), true); $data = mb_convert_encoding($plainText, 'ASCII'); // add PKCS#7 padding $blocksize = mcrypt_get_block_size('tripledes', 'ecb'); $paddingSize = $blocksize - (strlen($data) % $blocksize); $data .= str_repeat(chr($paddingSize), $paddingSize); // encrypt password $encData = mcrypt_encrypt('tripledes', $desKey, $data, 'ecb'); echo base64_encode($encData); }

I know I needed to add the true argument for the md5 function, and I know I needed to add the PKCS7 padding.

I haven't had a chance to check it against the C# code, because I'm still installing visual studio on my computer. Is there anything I'm missing? Do I need to add an IV?

EDIT: I tested the C# code, and saw that it was not giving same result. I fixed some things, and now have the DES.Key and Buffer variables from C# in PHP, giving the correct results.

EDIT again: It's fixed. All I had to do was append the first 8 characters to the end of the hashed key.

$desKey .= substr($desKey,0,8);

After I added the padding section, I was getting no response, because I was mistakenly trying to use $desKey as a function. Was should be there in its place? — mattslone
– mattslone, Commented Jul 27, 2015 at 15:01

mattslone · Accepted Answer · 2015-07-27 18:21:14Z

This is what I eventually came up with. It's worked so far for me on the few examples I've tried.

function encryptData($key, $plainText) { $byte = mb_convert_encoding($key, 'ASCII'); $desKey = md5(utf8_encode($byte), true); $desKey .= substr($desKey,0,8); $data = mb_convert_encoding($plainText, 'ASCII'); // add PKCS#7 padding $blocksize = mcrypt_get_block_size('tripledes', 'ecb'); $paddingSize = $blocksize - (strlen($data) % $blocksize); $data .= str_repeat(chr($paddingSize), $paddingSize); // encrypt password $encData = mcrypt_encrypt('tripledes', $desKey, $data, 'ecb'); echo base64_encode($encData); } encryptData('key', 'pass');

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