using System;

using System.Security.Cryptography;

using System.Text;

using System.IO;

​

public class Program

{

    public static void Main()

    {

        long idPerson = 123;

        Console.WriteLine(EncryptId(idPerson,"owrngvowrhgoi4eht_!@#T$dsfnasolfb"));

    }

    public static string EncryptId(long value, string password)

        {

            var key = DeriveKey(password);

            using var aesAlg = Aes.Create();

            aesAlg.Key = key;

            aesAlg.IV = new byte[16];

​

            using var encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

            using var msEncrypt = new MemoryStream();

            using var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);

            var buffer = BitConverter.GetBytes(value);

            csEncrypt.Write(buffer, 0, buffer.Length);

            csEncrypt.FlushFinalBlock();

            return Convert.ToBase64String(msEncrypt.ToArray()); ;

        }

​

        public static long DecryptId(string encryptedId, string password)

        {

            var cipherText = Convert.FromBase64String(encryptedId);

            var key = DeriveKey(password);

            using var aesAlg = Aes.Create();

            aesAlg.Key = key;

            aesAlg.IV = new byte[16];

​

            using var decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

            using var msDecrypt = new MemoryStream(cipherText);

            using var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read);

            byte[] buffer = new byte[sizeof(long)];

            csDecrypt.Read(buffer, 0, buffer.Length);

            return BitConverter.ToInt64(buffer, 0);

        }

​

        private static byte[] DeriveKey(string password)

        {

            using var keyGenerator = new Rfc2898DeriveBytes(password, Encoding.UTF8.GetBytes("Salt"), 10000);

            return keyGenerator.GetBytes(16);

        }

}