TripleDes decryption with some ivalid data at the begining
===

I am trying to decrypt data using tripleDes. Everything looks fine but it has some invalid characters at the beginning? What am I doing wrong? For same data if call this function again and again these first few characters are always different but the rest of the data is same.

I am passing useHashing to false.

 public static byte[] GetTripleDesDecryption(string dataToDecrypt, byte[] key, bool useHashing)
        {
            byte[] keyArray;
            byte[] plainbytes = null;
            byte[] cipherbytes;
          
            try
            {
                if (useHashing)
                {
                    MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
                    keyArray = hashmd5.ComputeHash(key);
                    hashmd5.Clear();
                }
                else
                    keyArray = key;

                using (TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider())
                {
                    tdes.Key = keyArray;
                    tdes.Mode = CipherMode.CBC;
                    tdes.Padding = PaddingMode.None;

                    using (ICryptoTransform cTransform = tdes.CreateDecryptor())
                    {
                        cipherbytes = Convert.FromBase64String(dataToDecrypt);
                        plainbytes = cTransform.TransformFinalBlock(cipherbytes, 0, cipherbytes.Length);
                    }
                }
            }
            catch (Exception e)
            {
                LogMessage(e.Message + " Attribute Parsing error. DataToDecrypt = " + dataToDecrypt);
                throw e;
            }
            return plainbytes;
        }

This is what I get:

"�{c��]�sertion xmlns:saml=\"urn:oasis:names:tc:SAML:2.0:assertion\"><saml:AttributeStatement><saml:Attribute Name=\"userID\"><saml:AttributeValue>456</saml:AttributeValue></saml:Attribute><saml:Attribute Name=\"financialInstitutionNumber\"><saml:AttributeValue>303986258</saml:AttributeValue></saml:Attribute><saml:Attribute Name=\"password\"><saml:AttributeValue>galaxy</saml:AttributeValue></saml:Attribute></saml:AttributeStatement></saml:Assertion>   "

