md5加密篇（一）

    /// <summary>
        /// 获取文件的md5摘要
        /// </summary>
        /// <param name="sFile">文件流</param>
        /// <returns>MD5摘要结果</returns>
        public static string GetAbstractToMD5(Stream sFile)
        {
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] result = md5.ComputeHash(sFile);
            StringBuilder sb = new StringBuilder(32);
            for (int i = 0; i < result.Length; i++)
            {
                sb.Append(result[i].ToString("x").PadLeft(2, '0'));
            }
            return sb.ToString();
        }

        /// <summary>
        /// 获取文件的md5摘要
        /// </summary>
        /// <param name="dataFile">文件流</param>
        /// <returns>MD5摘要结果</returns>
        public static string GetAbstractToMD5(byte[] dataFile)
        {
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] result = md5.ComputeHash(dataFile);
            StringBuilder sb = new StringBuilder(32);
            for (int i = 0; i < result.Length; i++)
            {
                sb.Append(result[i].ToString("x").PadLeft(2, '0'));
            }
            return sb.ToString();
        }

        /// <summary>
        /// 签名字符串
        /// </summary>
        /// <param name="prestr">需要签名的字符串</param>
        /// <param name="key">密钥</param>
        /// <param name="_input_charset">编码格式</param>
        /// <returns>签名结果</returns>
        public static string Md5Sign(string prestr, string key, string _input_charset)
        {
            StringBuilder sb = new StringBuilder(32);

            prestr = prestr + key;

            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] t = md5.ComputeHash(Encoding.GetEncoding(_input_charset).GetBytes(prestr));
            for (int i = 0; i < t.Length; i++)
            {
                sb.Append(t[i].ToString("x").PadLeft(2, '0'));
            }

            return sb.ToString();
        }


        /// <summary>
        /// 验证签名
        /// </summary>
        /// <param name="prestr">需要签名的字符串</param>
        /// <param name="sign">签名结果</param>
        /// <param name="key">密钥</param>
        /// <param name="_input_charset">编码格式</param>
        /// <returns>验证结果</returns>
        public static bool Md5Verify(string prestr, string sign, string key, string _input_charset)
        {
            string mysign = Md5Sign(prestr, key, _input_charset);
            if (mysign == sign)
            {
                return true;
            }
            else
            {
                return false;
            }
        }