Ruby OpenSSL::Cipher::CipherError (key not set) - asp.net

Question

I am trying to port an existing .net encryption code to ruby. But stuck with the key not set error.
Bellow is the .net code to encrypt a string.
private static string Encrypt(string strToEncrypt, string saltValue, string password)
{
using (var csp = new AesCryptoServiceProvider())
{
ICryptoTransform e = GetCryptoTransform(csp, true, saltValue, password);
byte[] inputBuffer = Encoding.UTF8.GetBytes(strToEncrypt);
byte[] output = e.TransformFinalBlock(inputBuffer, 0, inputBuffer.Length);
string encrypted = Convert.ToBase64String(output);
return encrypted;
}
}
private static ICryptoTransform GetCryptoTransform(AesCryptoServiceProvider csp, bool encrypting, string saltValue, string password)
{
csp.Mode = CipherMode.CBC;
csp.Padding = PaddingMode.PKCS7;
var passWord = password;
var salt = saltValue;
//a random Init. Vector. just for testing
String iv = "e675f725e675f123";
var spec = new Rfc2898DeriveBytes(Encoding.UTF8.GetBytes(passWord), Encoding.UTF8.GetBytes(salt), 1000);
byte[] key = spec.GetBytes(16);
csp.IV = Encoding.UTF8.GetBytes(iv);
csp.Key = key;
if (encrypting)
{
return csp.CreateEncryptor();
}
return csp.CreateDecryptor();
}
I have used Ruby's OpenSSL::PKCS5 library to generate key and OpenSSL::Cipher to encrypt using AES algorithm like bellow.
def aes_encrypt(input_string)
cipher = OpenSSL::Cipher.new('AES-128-CBC')
cipher.encrypt
key = encryption_key
iv = cipher.random_iv
cipher.update(input_string) + cipher.final
end
def encryption_key
OpenSSL::PKCS5.pbkdf2_hmac_sha1(PASSWORD, SALT, 1000, 16)
end
Can anyone let know where I am missing? (Padding ?)