using System;

using System.Security.Cryptography;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        var hash = EncryptSHA256("123456");

        Console.WriteLine(hash);

    }

​

    static String EncryptSHA256(String str)

    {

        if (str == null)

            str = "";

        var bytes = Encoding.Default.GetBytes(str);

        var sha = new SHA256Managed();

        bytes = sha.ComputeHash(bytes);

        var rs = Convert.ToBase64String(bytes);

        sha.Clear();

        return rs;

    }

}