C#中RSA加密解密和签名与验证的实现

RSA加密算法是一种非对称加密算法。在公钥加密标准和电子商业中RSA被广泛使用。RSA是1977年由罗纳德•李维斯特（Ron Rivest）、阿 迪•萨莫尔（Adi Shamir）和伦纳德•阿德曼（Leonard Adleman）一起提出的。当时他们三人都在麻省理工学院工作。RSA就是他们 三人姓氏开头字母拼在一起组成的。.Net的推出，我们能够利用.Net Framework中的类提供的加密服务来保证数据安全。目前应用较为广泛的加 密方法是使用RSA算法进行加密。在.Net Framework中与RSA加密算法相关的类主要有两个：RSA 类和 RSACryptoServiceProvider 类。按照MSDN的说法RSA 类是“表示 RSA 算法的所有实现均从中继承的基类”，而 RSACryptoServiceProvider 类是“使用加密服务提供程序 (CSP) 提供的 RSA 算法的实现执行不对称加密和解密”。另 外，“表示 RSA 算法的标准参数”的RSAParameters 结构也是很重要的，它保存了RSA算法的参数。
这里具体讲述一下在C#中如何使用框架提供的RSA算法来对我们的信息加密、签名、验证签名、解密的这个几个步骤的实现

  class Program
    {
        static void Main()
        {
            try
            {
                //string str_DataToSign = @"Data to Sign!Data to Sign!Data to Sign!";
                //Console.WriteLine("原文：" + str_DataToSign);
                //Console.WriteLine("长度：" + str_DataToSign.Length.ToString());
                //Console.WriteLine();

                string filePath = @"C:md5main.js";
                string str_DataToSign = GetFileMD5(filePath);
                Console.WriteLine(str_DataToSign);
                //WriteDateToFile(@"C:md5md5.txt", str_DataToSign);


                RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider();

                string str_Private_Key = Convert.ToBase64String(RSAalg.ExportCspBlob(true));
                string str_Public_Key = Convert.ToBase64String(RSAalg.ExportCspBlob(false));
                Console.WriteLine("公钥：" + str_Public_Key);
                //WriteDateToFile(@"C:md5public.txt",str_Public_Key);
                Console.WriteLine();
                Console.WriteLine("私钥：" + str_Private_Key);
                //WriteDateToFile(@"C:md5private.txt", str_Private_Key);
                Console.WriteLine();

                string str_SignedData = HashAndSign(str_DataToSign, str_Private_Key);// Hash and sign the data.
                Console.WriteLine("签名数据：" + str_SignedData);
                //WriteDateToFile(@"C:md5sign.txt", str_SignedData);
                Console.WriteLine();

                if (VerifySignedHash(str_DataToSign, str_SignedData, str_Public_Key))
                {
                    Console.WriteLine("验证签名OK.");
                }
                else
                {
                    Console.WriteLine("签名不匹配!");
                }
                Console.ReadKey();
            }
            catch (ArgumentNullException)
            {
                Console.WriteLine("The data was not signed or verified");
            }
        }

        //对数据签名
        public static string HashAndSign(string str_DataToSign, string str_Private_Key)
        {
            ASCIIEncoding ByteConverter = new ASCIIEncoding();
            byte[] DataToSign = ByteConverter.GetBytes(str_DataToSign);
            try
            {
                RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider();
                RSAalg.ImportCspBlob(Convert.FromBase64String(str_Private_Key));
                byte[] signedData = RSAalg.SignData(DataToSign, new SHA1CryptoServiceProvider());
                string str_SignedData = Convert.ToBase64String(signedData);
                return str_SignedData;
            }
            catch (CryptographicException e)
            {
                Console.WriteLine(e.Message);
                return null;
            }
        }

        //验证签名
        public static bool VerifySignedHash(string str_DataToVerify, string str_SignedData, string str_Public_Key)
        {
            byte[] SignedData = Convert.FromBase64String(str_SignedData);

            ASCIIEncoding ByteConverter = new ASCIIEncoding();
            byte[] DataToVerify = ByteConverter.GetBytes(str_DataToVerify);
            try
            {
                RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider();
                RSAalg.ImportCspBlob(Convert.FromBase64String(str_Public_Key));

                return RSAalg.VerifyData(DataToVerify, new SHA1CryptoServiceProvider(), SignedData);

            }
            catch (CryptographicException e)
            {
                Console.WriteLine(e.Message);

                return false;
            }
        }

        /// <summary>
        /// 对文件进行MD5加密
        /// </summary>
        /// <param name="filepath">文件路径</param>
        /// <returns></returns>
        public static string GetFileMD5(string filepath)
        {
            StringBuilder sb = new StringBuilder();
            using (MD5 md5 = MD5.Create())
            {
                using (FileStream fs = File.OpenRead(filepath))
                {
                    byte[] newB = md5.ComputeHash(fs);
                    foreach (byte item in newB)
                    {
                        sb.Append(item.ToString("x2"));
                    }
                }
            }

            return sb.ToString();
        }

        /// <summary>
        /// 写文件操作
        /// </summary>
        /// <param name="filePath"></param>
        /// <param name="content"></param>
        public static void WriteDateToFile(string filePath, string content)
        {
            using (StreamWriter sw = new StreamWriter(File.Open(filePath, FileMode.Create, FileAccess.Write, FileShare.None)))
            {
                //写入文件  
                sw.WriteLine(content);
                sw.Flush();
            }
        }
    }

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