System.Convert.ToBase64String C# (CSharp) Method

        public static String ToBase64String(byte[] inArray) {
            if (inArray==null) {
                throw new ArgumentNullException("inArray");
            }
            return ToBase64String(inArray, 0, inArray.Length, Base64FormattingOptions.None);
        }

        public static string Encrypt(this string plainText)
        {
            if (IsEncrypted(plainText))
            {
                return(plainText);
            }

            var plainTextBytes = UTF8.GetBytes(plainText);

            var keyBytes     = new Rfc2898DeriveBytes(PASSWORD_HASH, ASCII.GetBytes(SALT_KEY)).GetBytes(256 / 8);
            var symmetricKey = new RijndaelManaged()
            {
                Mode = CipherMode.CBC, Padding = PaddingMode.Zeros
            };
            var encryptor = symmetricKey.CreateEncryptor(keyBytes, ASCII.GetBytes(VI_KEY));


            using (var memoryStream = new MemoryStream())
            {
                using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                {
                    cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                    cryptoStream.FlushFinalBlock();
                    return(ENCRYPTION_INDICATOR + Convert.ToBase64String(memoryStream.ToArray()));
                }
            }
        }