Decrypt C# RIJNDAEL encoded text in PHP

I need to decrypt a string as part of an authorization process.

The documentation specifies that the authorization string was encrypted with the following settings:

• Padding of input data: PKCS*7
• Password byte array is 32 bytes long. Password string is converted to UTF-16 encoded byte array and byte array is then padded with zeroes up to length of 32 bytes. Longer passwords are truncated.

The C# example:

 /// <summary> /// Decrypts a string. /// </summary> /// <param name="content">The string to decrypt.</param> /// <param name="password">The password to use.</param> /// <returns>The decrypted string.</returns> private static string DecryptString(string content, string password) { Rijndael aes; byte[] retVal = null; byte[] contentBytes; byte[] passwordBytes; byte[] ivBytes; try { contentBytes = Convert.FromBase64String(content); //Create the password and initial vector bytes passwordBytes = new byte[32]; ivBytes = new byte[16]; Array.Copy(Encoding.Unicode.GetBytes(password), passwordBytes, Encoding.Unicode.GetBytes(password).Length); Array.Copy(passwordBytes, ivBytes, 16); //Create the cryptograpy object using (aes = Rijndael.Create()) { aes.Key = passwordBytes; aes.IV = ivBytes; aes.Padding = PaddingMode.PKCS7; //Decrypt retVal = aes.CreateDecryptor().TransformFinalBlock(contentBytes, 0, contentBytes.Length); } } catch { } return Encoding.Unicode.GetString(retVal); } 

The same function was discussed here, but for JAVA: Decrypt C# RIJNDAEL encoded text

I tried to decrypt it with the following function but the result is different than expected:

function decrypt($string, $pass){ $iv = substr($pass, 0, 16); $data = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $pass, base64_decode($string), MCRYPT_MODE_CBC, $iv); $pad = ord($data[strlen($data) - 1]); return substr($data, 0, -$pad); } 

The ecrypted string "7iTdZnp0DtGnIfwwqY4W/glbLLVZ0+asVLAuz13PzrW0wM6HC7rNuQvcG8JDSehyYeBJARdXHgLo9hRL9sBz3fN5LJ8cro3o0kFnAao2YRU="

should decrypt to

"ldYWMFlSbcki6LMl3rkNfGavnt8VqmZd" 

using the password "GAT"

I think it has something to do with the password / iv / encoding