Aes Encryption In c#

gistfile1.txt

            public static string EncryptStringToBytes(string plainText, string KeyString, string IVString)
            {
                var Key = Convert.FromBase64String(KeyString);
                var IV = Convert.FromBase64String(IVString);
                // Check arguments.
                if (plainText == null || plainText.Length <= 0)
                    throw new ArgumentNullException("plainText");
                if (Key == null || Key.Length <= 0)
                    throw new ArgumentNullException("Key");
                if (IV == null || IV.Length <= 0)
                    throw new ArgumentNullException("IV");
                byte[] encrypted;
                // Create an RijndaelManaged object
                // with the specified key and IV.
                using (RijndaelManaged rijAlg = new RijndaelManaged())
                {
                    rijAlg.Key = Key;
                    rijAlg.IV = IV;

                    // Create an encryptor to perform the stream transform.
                    ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);

                    // Create the streams used for encryption.
                    using (MemoryStream msEncrypt = new MemoryStream())
                    {
                        using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                        {
                            using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                            {

                                //Write all data to the stream.
                                swEncrypt.Write(plainText);
                            }
                            encrypted = msEncrypt.ToArray();
                        }
                    }
                }

                // Return the encrypted bytes from the memory stream.
                return Convert.ToBase64String(encrypted);
            }