MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();
var Sign = BitConverter.ToString(MD5.ComputeHash(Encoding.GetEncoding("utf-8").GetBytes(result))).Replace("-", "").ToLower();
将编码从gb2313改为utf-8。
原文：http://www.cnblogs.com/Cchblogs/p/6832496.html