using System;

using System.Text;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        string key=KeyGenerator.GetUniqueKey("V9lNRDBFapXO433Nkd0soaQN1PSmnnTVyFkJFmKrpGe2vh7GvtZtnTamFmhP2lsCaLSnstPDKEULpl06".Length);

        Console.WriteLine("Token - " + key);

    }

}

​

 public class KeyGenerator

    {

        internal static readonly char[] chars =

            "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890".ToCharArray(); 

​

        public static string GetUniqueKey(int size)

        {            

            byte[] data = new byte[4*size];

            using (RNGCryptoServiceProvider crypto = new RNGCryptoServiceProvider())

            {

                crypto.GetBytes(data);

            }

            StringBuilder result = new StringBuilder(size);

            for (int i = 0; i < size; i++)

            {

                var rnd = BitConverter.ToUInt32(data, i * 4);

                var idx = rnd % chars.Length;

​

                result.Append(chars[idx]);

            }

​

            return result.ToString();

        }

​

        public static string GetUniqueKeyOriginal_BIASED(int size)

        {

            char[] chars =

                "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890".ToCharArray();

            byte[] data = new byte[size];

            using (RNGCryptoServiceProvider crypto = new RNGCryptoServiceProvider())

            {

                crypto.GetBytes(data);

            }

            StringBuilder result = new StringBuilder(size);

            foreach (byte b in data)

            {

                result.Append(chars[b % (chars.Length)]);

            }

            return result.ToString();

        }

    }