using System;

using System.Security.Cryptography;                 

public class Program

{

    public static void Main()

    {

        Console.WriteLine("PasswordString 原始密碼字串");

        Console.WriteLine("Hello World");

        Console.WriteLine("=======================================");

        Console.WriteLine("PasswordHash, same password have different hash and salt 密碼雜湊值，相同的密碼也會有不同的雜湊和鹽");

        Console.WriteLine(PasswordHash.GetPasswordHash("Hello World"));

        Console.WriteLine(PasswordHash.GetPasswordHash("Hello World"));

        Console.WriteLine(PasswordHash.GetPasswordHash("Hello World"));

        Console.WriteLine("=======================================");

        Console.WriteLine("VerifyPasswordHash 驗證密碼雜湊是否與輸入的密碼相同");

        Console.WriteLine(PasswordHash.VerifyPasswordHash("Hello World","4096:hQnjEQoZH9Q2h6bCkPirW4dKbU1erHnyicjca98OkA4=:++Yslxkt1IBY0e87OgmzBbBSgRuRlcpwPb5fMkvWgtQ="));

        Console.WriteLine("=======================================");

        Console.WriteLine("Memory is high 可以觀察到右邊消耗記憶體不少");

    }

    class PasswordHash

    {

        private const int SaltByteSize = 32;

        private const int HashByteSize = 32;

        private const int Iterations = 4096;

​

        private static string GetSalt()

        {

            var cryptoProvider = new RNGCryptoServiceProvider();

            byte[] b_salt = new byte[SaltByteSize];

            cryptoProvider.GetBytes(b_salt);

            return Convert.ToBase64String(b_salt);

        }

​

        public static string GetPasswordHash(string password)

        {

            string salt = GetSalt();

​

            byte[] saltBytes = Convert.FromBase64String(salt);

            byte[] derived;

​

            using (var pbkdf2 = new Rfc2898DeriveBytes(

                password,

                saltBytes,

                Iterations,

                HashAlgorithmName.SHA512))

            {

                derived = pbkdf2.GetBytes(HashByteSize);

            }

​

            return string.Format("{0}:{1}:{2}", Iterations, Convert.ToBase64String(derived), Convert.ToBase64String(saltBytes));

        }

​

        public static bool VerifyPasswordHash(string password, string hash)

        {

            try

            {

                string[] parts = hash.Split(new char[] { ':' });

​

                byte[] saltBytes = Convert.FromBase64String(parts[2]);

                byte[] derived;

​

                int iterations = Convert.ToInt32(parts[0]);

​

                using (var pbkdf2 = new Rfc2898DeriveBytes(

                    password,

                    saltBytes,

                    iterations,

                    HashAlgorithmName.SHA512))

                {

                    derived = pbkdf2.GetBytes(HashByteSize);

                }

​

                string new_hash = string.Format("{0}:{1}:{2}", Iterations, Convert.ToBase64String(derived), Convert.ToBase64String(saltBytes));

​

                return hash == new_hash;

            }

            catch

            {

                return false;

            }

        }

    }

}