MD5给密码加密

            MD5 md5 = MD5.Create();
            byte[] buffer = System.Text.Encoding.UTF8.GetBytes(msg);
            byte[] md5Buffer = md5.ComputeHash(buffer);
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < md5Buffer.Length; i++)
            {
                sb.Append(md5Buffer[i].ToString("x2"));
            }
            return sb.ToString();