using System;

using System.IO;

using System.Security.Cryptography;

public class Program

{

    //https://stackoverflow.com/questions/52145133/encrypted-string-length-in-c-sharp

    public static void Main()

    {

        var txt="someone[a]somedomain.com";

        var cypher = Encrypt(txt, key:"EJlzmwq090f7Ckcoe1zuS1EscP2hpTcs8l/ZT69Uj5U=", salt:"Neg4LxF01KcSZ1Thw6jA3Q==");

        Console.WriteLine(string.Format("from {0} to {1} characters",txt.Length,cypher.Length));

        txt="someone.compleately.different[a]somedomain.com";

        cypher = Encrypt(txt, key:"EJlzmwq090f7Ckcoe1zuS1EscP2hpTcs8l/ZT69Uj5U=", salt:"Neg4LxF01KcSZ1Thw6jA3Q==");

        Console.WriteLine(string.Format("from {0} to {1} characters",txt.Length,cypher.Length));

    }

    protected static string Encrypt(string text, string key, string salt)

        {

            if (string.IsNullOrEmpty(text)) return string.Empty;

​

            return EncryptStringToBytes_Aes(text

                    , Convert.FromBase64String(key)

                    , Convert.FromBase64String(salt)

                    );

        }

    static string EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)

        {

            // 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 AesCryptoServiceProvider object

            // with the specified key and IV.

            using (AesCryptoServiceProvider aesAlg = new AesCryptoServiceProvider())

            {

                aesAlg.Key = Key;

                aesAlg.IV = IV;

                aesAlg.Padding = PaddingMode.ISO10126;

​

                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

​

                // Create the streams used for encryption.

                using (MemoryStream msEncrypt = new MemoryStream())

                {

                    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);

        }

}