using System;

using System.Text;

using System.Security.Cryptography;

​

public class Program

{

    private const int SecretLength = 5;

    public static void Main()

    {

        var secret = GenerateSecret();

        Console.WriteLine(secret);

    }

​

    private static string GenerateSecret()

    {

        var length = SecretLength / 2 + SecretLength % 2;

        var buffer = new byte[length];

        using (var random = RandomNumberGenerator.Create())

        {

            random.GetBytes(buffer);

        }

​

        return BitConverter.ToString(buffer).Replace("-", string.Empty).Substring(0, SecretLength);

    }

​

    private static string Sha256(string input)

    {

        using (var sha = SHA256.Create())

        {

            var bytes = Encoding.UTF8.GetBytes(input);

            var hash = sha.ComputeHash(bytes);

            return Convert.ToBase64String(hash);

        }

    }

}