Decryption In Stored Procedure

byte[] keyArray;
//get the byte code of the string

//byte[] toEncryptArray = Convert.FromBase64String(cipherString);
byte[] toEncryptArray = Convert.FromBase64String(cipherString.Replace("", "+"));

System.Configuration.AppSettingsReader settingsReader =
new AppSettingsReader();
//Get your key from config file to open the lock!
//string key = (string)settingsReader.GetValue("SecurityKey",
// typeof(String));
string key = "123";

if (useHashing)
{
//if hashing was used get the hash code with regards to your key
MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
//release any resource held by the MD5CryptoServiceProvider

hashmd5.Clear();
}
else
{
//if hashing was not implemented get the byte code of the key
keyArray = UTF8Encoding.UTF8.GetBytes(key);
}

TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
//set the secret key for the tripleDES algorithm
tdes.Key = keyArray;
//mode of operation. there are other 4 modes.
//We choose ECB(Electronic code Book)

tdes.Mode = CipherMode.ECB;
//padding mode(if any extra byte added)
tdes.Padding = PaddingMode.PKCS7;

ICryptoTransform cTransform = tdes.CreateDecryptor();
byte[] resultArray = cTransform.TransformFinalBlock(
toEncryptArray, 0, toEncryptArray.Length);
//Release resources held by TripleDes Encryptor
tdes.Clear();
//return the Clear decrypted TEXT
return UTF8Encoding.UTF8.GetString(resultArray);

The above mentioned is the method that i am using