jetherald/JetHerald/TokenHelper.cs

using System;
using System.Security.Cryptography;

namespace JetHerald
{
    public static class TokenHelper
    {
        static RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
        static byte[] buf = new byte[24];
        static readonly object SyncLock = new object();

        public static string GetToken()
        {
            lock (SyncLock)
            {
                rng.GetBytes(buf);
                return Convert.ToBase64String(buf).Replace('+', '_').Replace('/', '_');
            }
        }
    }
}