RSA不对称加密，公钥加密私钥解密，私钥加密公钥解密

RSA算法是第一个能同时用于加密和数字签名的算法，也易于理解和操作。 RSA是被研究得最广泛的公钥算法，从提出到现在已近二十年，经历了各种攻击的考验，逐渐为人们接受，普遍认为是目前最优秀的公钥方案之一。RSA的安全性依赖于大数的因子分解，但并没有从理论上证明破译RSA的难度与大数分解难度等价。

.NET提供常用的加密算法类，支持RSA的类是RSACryptoServiceProvider（命名空间：System.Security.Cryptography），但只支持公钥加密，私钥解密。RSACryptoServiceProvider类包括：Modulus、Exponent、P、Q、DP、DQ、InverseQ、D等8个属性，其中Modulus和Exponent就是公钥，Modulus和D就是私钥，RSACryptoServiceProvider类提供导出公钥的方法，也提供导出私钥的方法，但导出的私钥包含上面8个属性，显然要用RSACryptoServiceProvider实现私钥加密公钥是不可行的。

    从RSA的原理来看，公钥加密私钥解密和私钥加密公钥解密应该是等价的，在某些情况下，比如共享软件加密，我们需要用私钥加密注册码或注册文件，发给用户，用户用公钥解密注册码或注册文件进行合法性验证。

不对称密钥

.NET Framework 为不对称加密提供了 RSACryptoServiceProvider 和 DSACryptoServiceProvider 类。这些类在您使用默认构造函数创建新实例时创建一个公钥/私钥对。既可以存储不对称密钥以用在多个会话中，也可以只为一个会话生成不对称密钥。公钥可以被广泛地使用，私钥应被严密地保护起来。

每当创建不对称算法类的新实例时，都生成一个公钥/私钥对。创建该类的新实例后，可以用以下两种方法之一提取密钥信息：

• ToXMLString 方法，它返回密钥信息的 XML 表示形式。导出密钥--xml形式的字符串

• 对应的方法：FromXmlString通过 XML 字符串中的密钥信息初始化RSA 对象。 导入密钥

• ExportParameters 方法，它返回RSAParameters 结构以保存密钥信息。导出密钥--参数形式

• ImportParameters导入指定的RSAParameters。 （重写RSA.ImportParameters(RSAParameters)。）导入密钥

两个方法都接受布尔值，该值指示是只返回公钥信息还是同时返回公钥和私钥信息。通过使用 ImportParameters 方法，可以将 RSACryptoServiceProvider 类初始化为 RSAParameters 结构的值。

下面的代码示例创建 RSACryptoServiceProvider 类的一个新实例，创建一个公钥/私钥对，并将公钥信息保存在RSAParameters 结构中

//Generate a public/private key pair.
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
//Save the public key information to an RSAParameters structure.
RSAParameters RSAKeyInfo = RSA.ExportParameters(false);

一、公钥加密私钥解密

/// <summary>
   /// 公钥加密，私钥解密
   /// </summary>
   public class RSAEncryptHelper
   {

       /// <summary>
       /// 将字符串使用base64算法加密
       /// </summary>
       /// <param name="code_type">编码类型</param>
       /// <param name="code">待加密的字符串</param>
       /// <returns>加密后的字符串</returns>
       public string EncodeBase64(string code_type, string code)
       {
           string encode = "";
           byte[] bytes = Encoding.GetEncoding(code_type).GetBytes(code); //将一组字符编码为一个字节序列.
           try
           {
               encode = Convert.ToBase64String(bytes); //将8位无符号整数数组的子集转换为其等效的,以64为基的数字编码的字符串形式.
           }
           catch
           {
               encode = code;
           }
           return encode;
       }

       /// <summary>
       /// 将字符串使用base64算法解密
       /// </summary>
       /// <param name="code_type">编码类型</param>
       /// <param name="code">已用base64算法加密的字符串</param>
       /// <returns>解密后的字符串</returns>
       public string DecodeBase64(string code_type, string code)
       {

           string decode = "";
           byte[] bytes = Convert.FromBase64String(code); //将2进制编码转换为8位无符号整数数组.
           try
           {
               decode = Encoding.GetEncoding(code_type).GetString(bytes); //将指定字节数组中的一个字节序列解码为一个字符串。
           }
           catch
           {
               decode = code;
           }
           return decode;
       }
       /// <summary>
       /// 获取本机的MAC地址
       /// </summary>
       /// <returns></returns>
       public static string GetLocalMac()
       {
           string mac = null;
           ManagementObjectSearcher query = new ManagementObjectSearcher("SELECT * FROM Win32_NetworkAdapterConfiguration");
           ManagementObjectCollection queryCollection = query.Get();
           foreach (ManagementObject mo in queryCollection)
           {
               if (mo["IPEnabled"].ToString() == "True")
                   mac = mo["MacAddress"].ToString();
           }
           return (mac);
       }

       /// <summary>
       /// 得到CPU序列号
       /// </summary>
       /// <returns></returns>
       public static string GetCpuID()
       {
           try
           {
               //获取CPU序列号代码
               string cpuInfo = "";//cpu序列号
               ManagementClass mc = new ManagementClass("Win32_Processor");
               ManagementObjectCollection moc = mc.GetInstances();
               foreach (ManagementObject mo in moc)
               {
                   cpuInfo = mo.Properties["ProcessorId"].Value.ToString();
               }
               moc = null;
               mc = null;
               return cpuInfo;
           }
           catch
           {
               return "unknow";
           }
           finally
           {
           }

       }
       /// <summary>

       /// 生成公私钥

       /// </summary>

       /// <param name="PrivateKeyPath"></param>

       /// <param name="PublicKeyPath"></param>

       public void RSAKey(string PrivateKeyPath, string PublicKeyPath)
       {

           try
           {

               RSACryptoServiceProvider provider = new RSACryptoServiceProvider();

               this.CreatePrivateKeyXML(PrivateKeyPath, provider.ToXmlString(true));

               this.CreatePublicKeyXML(PublicKeyPath, provider.ToXmlString(false));

           }

           catch (Exception exception)
           {

               throw exception;

           }

       }

       /// <summary>

       /// 对原始数据进行MD5加密

       /// </summary>

       /// <param name="m_strSource">待加密数据</param>

       /// <returns>返回机密后的数据</returns>

       public string GetHash(string m_strSource)
       {

           HashAlgorithm algorithm = HashAlgorithm.Create("MD5");

           byte[] bytes = Encoding.GetEncoding("GB2312").GetBytes(m_strSource);

           byte[] inArray = algorithm.ComputeHash(bytes);

           return Convert.ToBase64String(inArray);

       }

       /// <summary>

       /// RSA加密

       /// </summary>

       /// <param name="xmlPublicKey">公钥</param>

       /// <param name="m_strEncryptString">MD5加密后的数据</param>

       /// <returns>RSA公钥加密后的数据</returns>

       public string RSAEncrypt(string xmlPublicKey, string m_strEncryptString)
       {

           string str2;

           try
           {

               RSACryptoServiceProvider provider = new RSACryptoServiceProvider();

               provider.FromXmlString(xmlPublicKey);

               byte[] bytes = new UnicodeEncoding().GetBytes(m_strEncryptString);

               str2 = Convert.ToBase64String(provider.Encrypt(bytes, false));

           }

           catch (Exception exception)
           {

               throw exception;

           }

           return str2;

       }

       /// <summary>

       /// RSA解密

       /// </summary>

       /// <param name="xmlPrivateKey">私钥</param>

       /// <param name="m_strDecryptString">待解密的数据</param>

       /// <returns>解密后的结果</returns>

       public string RSADecrypt(string xmlPrivateKey, string m_strDecryptString)
       {

           string str2;

           try
           {

               RSACryptoServiceProvider provider = new RSACryptoServiceProvider();

               provider.FromXmlString(xmlPrivateKey);

               byte[] rgb = Convert.FromBase64String(m_strDecryptString);

               byte[] buffer2 = provider.Decrypt(rgb, false);

               str2 = new UnicodeEncoding().GetString(buffer2);

           }
           catch (Exception exception)
           {

               throw exception;

           }

           return str2;

       }

       /// <summary>

       /// 对MD5加密后的密文进行签名

       /// </summary>

       /// <param name="p_strKeyPrivate">私钥</param>

       /// <param name="m_strHashbyteSignature">MD5加密后的密文</param>

       /// <returns></returns>

       public string SignatureFormatter(string p_strKeyPrivate, string m_strHashbyteSignature)
       {

           byte[] rgbHash = Convert.FromBase64String(m_strHashbyteSignature);

           RSACryptoServiceProvider key = new RSACryptoServiceProvider();

           key.FromXmlString(p_strKeyPrivate);

           RSAPKCS1SignatureFormatter formatter = new RSAPKCS1SignatureFormatter(key);

           formatter.SetHashAlgorithm("MD5");

           byte[] inArray = formatter.CreateSignature(rgbHash);

           return Convert.ToBase64String(inArray);

       }

       /// <summary>

       /// 签名验证

       /// </summary>

       /// <param name="p_strKeyPublic">公钥</param>

       /// <param name="p_strHashbyteDeformatter">待验证的用户名</param>

       /// <param name="p_strDeformatterData">注册码</param>

       /// <returns></returns>

       public bool SignatureDeformatter(string p_strKeyPublic, string p_strHashbyteDeformatter, string p_strDeformatterData)
       {

           try
           {

               byte[] rgbHash = Convert.FromBase64String(p_strHashbyteDeformatter);

               RSACryptoServiceProvider key = new RSACryptoServiceProvider();

               key.FromXmlString(p_strKeyPublic);

               RSAPKCS1SignatureDeformatter deformatter = new RSAPKCS1SignatureDeformatter(key);

               deformatter.SetHashAlgorithm("MD5");

               byte[] rgbSignature = Convert.FromBase64String(p_strDeformatterData);

               if (deformatter.VerifySignature(rgbHash, rgbSignature))
               {

                   return true;

               }

               return false;

           }

           catch
           {

               return false;

           }

       }

       /// <summary>

       /// 获取硬盘ID

       /// </summary>

       /// <returns>硬盘ID</returns>

       public string GetHardID()
       {

           string HDInfo = "";

           ManagementClass cimobject1 = new ManagementClass("Win32_DiskDrive");

           ManagementObjectCollection moc1 = cimobject1.GetInstances();

           foreach (ManagementObject mo in moc1)
           {

               HDInfo = (string)mo.Properties["Model"].Value;

           }

           return HDInfo;

       }

       /// <summary>

       /// 读注册表中指定键的值

       /// </summary>

       /// <param name="key">键名</param>

       /// <returns>返回键值</returns>

       private string ReadReg(string key)
       {

           string temp = "";

           try
           {

               RegistryKey myKey = Registry.LocalMachine;

               RegistryKey subKey = myKey.OpenSubKey(@"SOFTWARE/JX/Register");



               temp = subKey.GetValue(key).ToString();

               subKey.Close();

               myKey.Close();

               return temp;

           }

           catch (Exception)
           {

               throw;//可能没有此注册项;

           }



       }

       /// <summary>

       /// 创建注册表中指定的键和值

       /// </summary>

       /// <param name="key">键名</param>

       /// <param name="value">键值</param>

       private void WriteReg(string key, string value)
       {

           try
           {

               RegistryKey rootKey = Registry.LocalMachine.CreateSubKey(@"SOFTWARE/JX/Register");

               rootKey.SetValue(key, value);

               rootKey.Close();

           }

           catch (Exception)
           {

               throw;

           }

       }

       /// <summary>

       /// 创建公钥文件

       /// </summary>

       /// <param name="path"></param>

       /// <param name="publickey"></param>

       public void CreatePublicKeyXML(string path, string publickey)
       {

           try
           {

               FileStream publickeyxml = new FileStream(path, FileMode.Create);

               StreamWriter sw = new StreamWriter(publickeyxml);

               sw.WriteLine(publickey);

               sw.Close();

               publickeyxml.Close();

           }

           catch
           {

               throw;

           }

       }

       /// <summary>

       /// 创建私钥文件

       /// </summary>

       /// <param name="path"></param>

       /// <param name="privatekey"></param>

       public void CreatePrivateKeyXML(string path, string privatekey)
       {

           try
           {

               FileStream privatekeyxml = new FileStream(path, FileMode.Create);

               StreamWriter sw = new StreamWriter(privatekeyxml);

               sw.WriteLine(privatekey);

               sw.Close();

               privatekeyxml.Close();

           }

           catch
           {

               throw;

           }

       }

       /// <summary>

       /// 读取公钥

       /// </summary>

       /// <param name="path"></param>

       /// <returns></returns>

       public string ReadPublicKey(string path)
       {

           StreamReader reader = new StreamReader(path);

           string publickey = reader.ReadToEnd();

           reader.Close();

           return publickey;

       }

       /// <summary>

       /// 读取私钥

       /// </summary>

       /// <param name="path"></param>

       /// <returns></returns>

       public string ReadPrivateKey(string path)
       {

           StreamReader reader = new StreamReader(path);

           string privatekey = reader.ReadToEnd();

           reader.Close();

           return privatekey;

       }

       /// <summary>

       /// 初始化注册表，程序运行时调用，在调用之前更新公钥xml

       /// </summary>

       /// <param name="path">公钥路径</param>

       public void InitialReg(string path)
       {

           Registry.LocalMachine.CreateSubKey(@"SOFTWARE/JX/Register");

           Random ra = new Random();

           string publickey = this.ReadPublicKey(path);

           if (Registry.LocalMachine.OpenSubKey(@"SOFTWARE/JX/Register").ValueCount <= 0)
           {

               this.WriteReg("RegisterRandom", ra.Next(1, 100000).ToString());

               this.WriteReg("RegisterPublicKey", publickey);

           }

           else
           {

               this.WriteReg("RegisterPublicKey", publickey);

           }

       }
   }

二、私钥加密公钥解密

/// <summary>
   /// 非对称RSA加密类 可以参考
   /// http://www.cnblogs.com/hhh/archive/2011/06/03/2070692.html
   /// http://blog.csdn.net/zhilunchen/article/details/2943158
   /// http://www.cnblogs.com/yyl8781697/archive/2013/04/28/RSA.html
   /// 若是私匙加密 则需公钥解密
   /// 反正公钥加密 私匙来解密
   /// 需要BigInteger类来辅助
   /// </summary>
   public static class RSAHelper
   {
       /// <summary>
       /// RSA的容器 可以解密的源字符串长度为 DWKEYSIZE/8-11
       /// </summary>
       public const int DWKEYSIZE = 1024;

       /// <summary>
       /// RSA加密的密匙结构  公钥和私匙
       /// </summary>
       //public struct RSAKey
       //{
       //    public string PublicKey { get; set; }
       //    public string PrivateKey { get; set; }
       //}

       #region 得到RSA的解谜的密匙对
       /// <summary>
       /// 得到RSA的解谜的密匙对
       /// </summary>
       /// <returns></returns>
       //public static RSAKey GetRASKey()
       //{
       //    RSACryptoServiceProvider.UseMachineKeyStore = true;
       //    //声明一个指定大小的RSA容器
       //    RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(DWKEYSIZE);
       //    //取得RSA容易里的各种参数
       //    RSAParameters p = rsaProvider.ExportParameters(true);

       //    return new RSAKey()
       //    {
       //        PublicKey = ComponentKey(p.Exponent, p.Modulus),
       //        PrivateKey = ComponentKey(p.D, p.Modulus)
       //    };
       //}
       #endregion

       #region 检查明文的有效性 DWKEYSIZE/8-11 长度之内为有效 中英文都算一个字符
       /// <summary>
       /// 检查明文的有效性 DWKEYSIZE/8-11 长度之内为有效 中英文都算一个字符
       /// </summary>
       /// <param name="source"></param>
       /// <returns></returns>
       public static bool CheckSourceValidate(string source)
       {
           return (DWKEYSIZE / 8 - 11) >= source.Length;
       }
       #endregion

       #region 组合解析密匙
       /// <summary>
       /// 组合成密匙字符串
       /// </summary>
       /// <param name="b1"></param>
       /// <param name="b2"></param>
       /// <returns></returns>
       public static string ComponentKey(byte[] b1, byte[] b2)
       {
           List<byte> list = new List<byte>();
           //在前端加上第一个数组的长度值 这样今后可以根据这个值分别取出来两个数组
           list.Add((byte)b1.Length);
           list.AddRange(b1);
           list.AddRange(b2);
           byte[] b = list.ToArray<byte>();
           return Convert.ToBase64String(b);
       }

       /// <summary>
       /// 解析密匙
       /// </summary>
       /// <param name="key">密匙</param>
       /// <param name="b1">RSA的相应参数1</param>
       /// <param name="b2">RSA的相应参数2</param>
       private static void ResolveKey(string key, out byte[] b1, out byte[] b2)
       {
           //从base64字符串 解析成原来的字节数组
           byte[] b = Convert.FromBase64String(key);
           //初始化参数的数组长度
           b1 = new byte[b[0]];
           b2 = new byte[b.Length - b[0] - 1];
           //将相应位置是值放进相应的数组
           for (int n = 1, i = 0, j = 0; n < b.Length; n++)
           {
               if (n <= b[0])
               {
                   b1[i++] = b[n];
               }
               else
               {
                   b2[j++] = b[n];
               }
           }
       }
       #endregion

       #region 字符串加密解密 公开方法
       /// <summary>
       /// 字符串加密
       /// </summary>
       /// <param name="source">源字符串 明文</param>
       /// <param name="key">密匙</param>
       /// <returns>加密遇到错误将会返回原字符串</returns>
       public static string EncryptString(string source, string key)
       {
           string encryptString = string.Empty;
           byte[] d;
           byte[] n;
           try
           {
               if (!CheckSourceValidate(source))
               {
                   throw new Exception("source string too long");
               }
               //解析这个密钥
               ResolveKey(key, out d, out n);
               BigInteger biN = new BigInteger(n);
               BigInteger biD = new BigInteger(d);
               encryptString = EncryptString(source, biD, biN);
           }
           catch
           {
               encryptString = source;
           }
           return encryptString;
       }

       /// <summary>
       /// 字符串解密
       /// </summary>
       /// <param name="encryptString">密文</param>
       /// <param name="key">密钥</param>
       /// <returns>遇到解密失败将会返回空字符串</returns>
       public static string DecryptString(string encryptString, string key)
       {
           string source = string.Empty;
           byte[] e;
           byte[] n;
           try
           {
               //解析这个密钥
               ResolveKey(key, out e, out n);
               BigInteger biE = new BigInteger(e);
               BigInteger biN = new BigInteger(n);
               source = DecryptString(encryptString, biE, biN);
           }
           catch
           {
           }
           return source;
       }
       #endregion

       #region 字符串加密解密 私有  实现加解密的实现方法
       /// <summary>
       /// 用指定的密匙加密
       /// </summary>
       /// <param name="source">明文</param>
       /// <param name="d">可以是RSACryptoServiceProvider生成的D</param>
       /// <param name="n">可以是RSACryptoServiceProvider生成的Modulus</param>
       /// <returns>返回密文</returns>
       private static string EncryptString(string source, BigInteger d, BigInteger n)
       {
           int len = source.Length;
           int len1 = 0;
           int blockLen = 0;
           if ((len % 128) == 0)
               len1 = len / 128;
           else
               len1 = len / 128 + 1;
           string block = "";
           StringBuilder result = new StringBuilder();
           for (int i = 0; i < len1; i++)
           {
               if (len >= 128)
                   blockLen = 128;
               else
                   blockLen = len;
               block = source.Substring(i * 128, blockLen);
               byte[] oText = System.Text.Encoding.Default.GetBytes(block);
               BigInteger biText = new BigInteger(oText);
               BigInteger biEnText = biText.modPow(d, n);
               string temp = biEnText.ToHexString();
               result.Append(temp).Append("@");
               len -= blockLen;
           }
           return result.ToString().TrimEnd('@');
       }

       /// <summary>
       /// 用指定的密匙加密
       /// </summary>
       /// <param name="source">密文</param>
       /// <param name="e">可以是RSACryptoServiceProvider生成的Exponent</param>
       /// <param name="n">可以是RSACryptoServiceProvider生成的Modulus</param>
       /// <returns>返回明文</returns>
       private static string DecryptString(string encryptString, BigInteger e, BigInteger n)
       {
           StringBuilder result = new StringBuilder();
           string[] strarr1 = encryptString.Split(new char[] { '@' }, StringSplitOptions.RemoveEmptyEntries);
           for (int i = 0; i < strarr1.Length; i++)
           {
               string block = strarr1[i];
               BigInteger biText = new BigInteger(block, 16);
               BigInteger biEnText = biText.modPow(e, n);
               string temp = System.Text.Encoding.Default.GetString(biEnText.getBytes());
               result.Append(temp);
           }
           return result.ToString();
       }
       #endregion


       /// <summary>
       /// 将字符串使用base64算法加密
       /// </summary>
       /// <param name="code_type">编码类型</param>
       /// <param name="code">待加密的字符串</param>
       /// <returns>加密后的字符串</returns>
       public static string EncodeBase64(string code_type, string code)
       {
           string encode = "";
           byte[] bytes = Encoding.GetEncoding(code_type).GetBytes(code); //将一组字符编码为一个字节序列.
           try
           {
               encode = Convert.ToBase64String(bytes); //将8位无符号整数数组的子集转换为其等效的,以64为基的数字编码的字符串形式.
           }
           catch
           {
               encode = code;
           }
           return encode;
       }

       /// <summary>
       /// 将字符串使用base64算法解密
       /// </summary>
       /// <param name="code_type">编码类型</param>
       /// <param name="code">已用base64算法加密的字符串</param>
       /// <returns>解密后的字符串</returns>
       public static string DecodeBase64(string code_type, string code)
       {

           string decode = "";
           byte[] bytes = Convert.FromBase64String(code); //将2进制编码转换为8位无符号整数数组.
           try
           {
               decode = Encoding.GetEncoding(code_type).GetString(bytes); //将指定字节数组中的一个字节序列解码为一个字符串。
           }
           catch
           {
               decode = code;
           }
           return decode;
       }

       /// <summary>
       /// 读取公钥或私钥
       /// </summary>
       /// <param name="includePrivateparameters">为True则包含私钥</param>
       /// <param name="path">Xml格式保存的完整公/私钥路径</param>
       /// <returns>公钥或私钥参数形式 </returns>
       public static RSAParameters ReadKey(bool includePrivateparameters,string path)
       {
           using (StreamReader reader = new StreamReader(path))
           {
               string publickey = reader.ReadToEnd();
               RSACryptoServiceProvider rcp = new RSACryptoServiceProvider();
               rcp.FromXmlString(publickey);
               return rcp.ExportParameters(includePrivateparameters);
           }
       }

       /// <summary>
       /// 获取本机的MAC地址
       /// </summary>
       /// <returns></returns>
       public static string GetLocalMac()
       {
           string mac = null;
           ManagementObjectSearcher query = new ManagementObjectSearcher("SELECT * FROM Win32_NetworkAdapterConfiguration");
           ManagementObjectCollection queryCollection = query.Get();
           foreach (ManagementObject mo in queryCollection)
           {
               if (mo["IPEnabled"].ToString() == "True")
                   mac = mo["MacAddress"].ToString();
           }
           return (mac);
       }

       /// <summary>
       /// 得到CPU序列号
       /// </summary>
       /// <returns></returns>
       public static string GetCpuID()
       {
           try
           {
               //获取CPU序列号代码
               string cpuInfo = "";//cpu序列号
               ManagementClass mc = new ManagementClass("Win32_Processor");
               ManagementObjectCollection moc = mc.GetInstances();
               foreach (ManagementObject mo in moc)
               {
                   cpuInfo = mo.Properties["ProcessorId"].Value.ToString();
               }
               moc = null;
               mc = null;
               return cpuInfo;
           }
           catch
           {
               return "unknow";
           }
           finally
           {
           }

       }

       /// <summary>

       /// 获取硬盘ID

       /// </summary>

       /// <returns>硬盘ID</returns>

       public static string GetHardID()
       {

           string HDInfo = "";

           ManagementClass cimobject1 = new ManagementClass("Win32_DiskDrive");

           ManagementObjectCollection moc1 = cimobject1.GetInstances();

           foreach (ManagementObject mo in moc1)
           {

               HDInfo = (string)mo.Properties["Model"].Value;

           }

           return HDInfo;

       }

       /// <summary>

       /// 读注册表中指定键的值

       /// </summary>

       /// <param name="key">键名</param>

       /// <returns>返回键值</returns>

       private static string ReadReg(string key)
       {

           string temp = "";

           try
           {

               RegistryKey myKey = Registry.LocalMachine;

               RegistryKey subKey = myKey.OpenSubKey(@"SOFTWARE/JX/Register");



               temp = subKey.GetValue(key).ToString();

               subKey.Close();

               myKey.Close();

               return temp;

           }

           catch (Exception)
           {

               throw;//可能没有此注册项;

           }
       }

       /// <summary>

       /// 创建注册表中指定的键和值

       /// </summary>

       /// <param name="key">键名</param>

       /// <param name="value">键值</param>

       private static void WriteReg(string key, string value)
       {
           try
           {

               RegistryKey rootKey = Registry.LocalMachine.CreateSubKey(@"SOFTWARE/JX/Register");

               rootKey.SetValue(key, value);

               rootKey.Close();

           }

           catch (Exception)
           {

               throw;

           }

       }


   }

使用场景：如共享软件加密，我们需要用私钥加密注册码或注册文件，发给用户，用户用公钥解密注册码或注册文件进行合法性验证。

RSA算法实现激活码注册方式的原理如下：

1. 生成一对公钥E和私钥D（供软件注册模板和注册机使用）；

2. 用户安装软件后，软件注册模板提取用户机器指纹信息（如：MAC地址、CPU序列号、硬盘序列号等），并通过其它的编码算法（如BASE64）生成一个申请码C；

3. 用户将申请码C发给软件开发商。软件开发商通过注册机采用私钥D加密申请码C后生成激活码F。软件供应商将激活码F发给用户。

4. 用户输入激活码F，软件注册模板采用公钥E对激活码F解码后生成G(即：用户机器特征信息)，然后软件注册模板提取用户机器的特定信息后进行编码。将编码的结果与G进行比较，如果相等则用户合法，完成授权，否则授权失败。

//应用程序注册模块
   public partial class Form1 : Form
   {

       public Form1()
       {
           InitializeComponent();
       }

       private void Form1_Load(object sender, EventArgs e)
       {
           string cpu = RSAHelper.GetCpuID();
           string _申请码C = RSAHelper.EncodeBase64("utf-8", cpu);
           textEdit申请码.Text = _申请码C;
       }

       private void simpleButton注册_Click(object sender, EventArgs e)
       {
           string publicKeyPath = @"C://PublicKey.xml";
           RSAParameters pm = RSAHelper.ReadKey(false, publicKeyPath);

           string _PublicKey = RSAHelper.ComponentKey(pm.Exponent, pm.Modulus);

           string cpu = RSAHelper.DecryptString(textEdit激活码.Text, _PublicKey);
           if (cpu == textEdit申请码.Text)
           {
               MessageBox.Show("注册成功");
           }
           else
           {
               MessageBox.Show("注册失败");
           }
       }
   }

/// <summary>
   /// 注册机
   /// </summary>
   public partial class Form1 : Form
   {
       public Form1()
       {
           InitializeComponent();
       }

       private void simpleButton生成激活码_Click(object sender, EventArgs e)
       {
           string privateKeyPath = @"C://PrivateKey.xml";
           RSAParameters pm = RSAHelper.ReadKey(true, privateKeyPath);
           string _PrivateKey = RSAHelper.ComponentKey(pm.D, pm.Modulus);
           textEdit激活码.Text = RSAHelper.EncryptString(textEdit申请码.Text, _PrivateKey);
       }
   }