C#实现RSA加密解密

RSA公钥加密算法是1977年由Ron Rivest、Adi Shamirh和LenAdleman在（美国麻省理工学院）开发的。RSA取名来自开发他们三者的名字。
RSA的缺点:

• 产生密钥很麻烦，受到素数产生技术的限制，因而难以做到一次一密。

• 分组长度太大，为保证安全性，n 至少也要 600bits以上，使运算代价很高，尤其是速度较慢，较对称密码算法慢几个数量级；且随着大数分解技术的发展，这个长度还在增加，不利于数据格式的标准化。目前，SET(Secure Electronic Transaction)协议中要求CA采用2048bits长的密钥，其他实体使用1024比特的密钥。C)RSA密钥长度随着保密级别提高，增加很快。下表列出了对同一安全级别所对应的密钥长度。

C#中RSA的相关操作

• 生成公钥和私钥

  public class RSASecretKey
      {
          public RSASecretKey() { }
          public RSASecretKey(string privateKey, string publicKey)
          {
              PrivateKey = privateKey;
              PublicKey = publicKey;
          }
          public string PublicKey { get; set; }
          public string PrivateKey { get; set; }
          public override string ToString()
          {
              return string.Format(
                  "PrivateKey: {0}\r\nPublicKey: {1}", PrivateKey, PublicKey);
          }
  
          /// <summary>
          /// 生成公钥私钥
          /// </summary>
          /// <param name="keySize">the size of the key,must from 384 bits to 16384 bits in increments of 8 </param>
          /// <returns></returns>
          public RSASecretKey GenerateRSASecretKey(int keySize)
          {
              RSASecretKey rsaKey = new RSASecretKey();
              using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(keySize))
              {
                  rsaKey.PrivateKey = rsa.ToXmlString(true);
                  rsaKey.PublicKey = rsa.ToXmlString(false);
              }
              return rsaKey;
          }
          
      }

  

   

• 实现公钥加密私钥解密

      public class RSAHelper
      {
          /// <summary>
          /// 加密
          /// </summary>
          /// <param name="xmlPublicKey"></param>
          /// <param name="content"></param>
          /// <returns></returns>
          public string RSAEncrypt(string xmlPublicKey, string content)
          {
              string encryptedContent = string.Empty;
              using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
              {
                  rsa.FromXmlString(xmlPublicKey);
                  byte[] encryptedData = rsa.Encrypt(Encoding.Default.GetBytes(content), false);
                  encryptedContent = Convert.ToBase64String(encryptedData);
              }
              return encryptedContent;
          }
          /// <summary>
          /// 解密
          /// </summary>
          /// <param name="xmlPrivateKey"></param>
          /// <param name="content"></param>
          /// <returns></returns>
          public string RSADecrypt(string xmlPrivateKey, string content)
          {
              string decryptedContent = string.Empty;
              using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
              {
                  rsa.FromXmlString(xmlPrivateKey);
                  byte[] decryptedData = rsa.Decrypt(Convert.FromBase64String(content), false);
                  decryptedContent = Encoding.GetEncoding("gb2312").GetString(decryptedData);
              }
              return decryptedContent;
          }
  
  
      }

  密钥格式的转换

  C#中RSA公钥和私钥的格式都是XML的,而在其他语言如java中,生成的RSA密钥就是普通的Base64字符串,所以需要将C#xml格式的密钥转换成普通的Base64字符串,同时也要实现Base64密钥字符串生成C#中xml格式的密钥.
  安装 BouncyCastle 这个Nuget包
  PM > Install-Package BouncyCastle
  BouncyCastle项目网址
  BouncyCastlegithub地址
  构造一个RSAKeyConventer类

      using System;
      using System.Security.Cryptography;
      using Org.BouncyCastle.Asn1.Pkcs;
      using Org.BouncyCastle.Math;
      using Org.BouncyCastle.Pkcs;
      using Org.BouncyCastle.Asn1.X509;
      using Org.BouncyCastle.X509;
      using Org.BouncyCastle.Security;
      using Org.BouncyCastle.Crypto.Parameters;
  
      public class RSAKeyConverter
      {
          /// <summary>
          /// xml private key -> base64 private key string
          /// </summary>
          /// <param name="xmlPrivateKey"></param>
          /// <returns></returns>
          public static string FromXmlPrivateKey(string xmlPrivateKey)
          {
              string result = string.Empty;
              using(RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
              {
                  rsa.FromXmlString(xmlPrivateKey);
                  RSAParameters param = rsa.ExportParameters(true);
                  RsaPrivateCrtKeyParameters privateKeyParam = new RsaPrivateCrtKeyParameters(
                      new BigInteger(1, param.Modulus), new BigInteger(1, param.Exponent),
                      new BigInteger(1, param.D), new BigInteger(1, param.P),
                      new BigInteger(1, param.Q), new BigInteger(1, param.DP),
                      new BigInteger(1, param.DQ), new BigInteger(1, param.InverseQ));
                  PrivateKeyInfo privateKey = PrivateKeyInfoFactory.CreatePrivateKeyInfo(privateKeyParam);
                 
                  result = Convert.ToBase64String(privateKey.ToAsn1Object().GetEncoded());
              }
              return result;
          }
  
          /// <summary>
          /// xml public key -> base64 public key string
          /// </summary>
          /// <param name="xmlPublicKey"></param>
          /// <returns></returns>
          public static string FromXmlPublicKey(string xmlPublicKey)
          {
              string result = string.Empty;
              using(RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
              {
                  rsa.FromXmlString(xmlPublicKey);
                  RSAParameters p = rsa.ExportParameters(false);
                  RsaKeyParameters keyParams = new RsaKeyParameters(
                      false, new BigInteger(1,p.Modulus), new BigInteger(1, p.Exponent));
                  SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keyParams);
                  result = Convert.ToBase64String(publicKeyInfo.ToAsn1Object().GetEncoded());
              }
              return result;
          }
  
          /// <summary>
          /// base64 private key string -> xml private key
          /// </summary>
          /// <param name="privateKey"></param>
          /// <returns></returns>
          public static string ToXmlPrivateKey(string privateKey)
          {
              RsaPrivateCrtKeyParameters privateKeyParams =
                  PrivateKeyFactory.CreateKey(Convert.FromBase64String(privateKey)) as RsaPrivateCrtKeyParameters;
              using(RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
              {
                  RSAParameters rsaParams = new RSAParameters()
                  {
                      Modulus = privateKeyParams.Modulus.ToByteArrayUnsigned(),
                      Exponent = privateKeyParams.PublicExponent.ToByteArrayUnsigned(),
                      D = privateKeyParams.Exponent.ToByteArrayUnsigned(),
                      DP = privateKeyParams.DP.ToByteArrayUnsigned(),
                      DQ = privateKeyParams.DQ.ToByteArrayUnsigned(),
                      P = privateKeyParams.P.ToByteArrayUnsigned(),
                      Q = privateKeyParams.Q.ToByteArrayUnsigned(),
                      InverseQ = privateKeyParams.QInv.ToByteArrayUnsigned()
                  };
                  rsa.ImportParameters(rsaParams);
                  return rsa.ToXmlString(true);
              }
          }
  
          /// <summary>
          /// base64 public key string -> xml public key
          /// </summary>
          /// <param name="pubilcKey"></param>
          /// <returns></returns>
          public static string ToXmlPublicKey(string pubilcKey)
          {
              RsaKeyParameters p = 
                  PublicKeyFactory.CreateKey(Convert.FromBase64String(pubilcKey)) as RsaKeyParameters;
              using(RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
              {
                  RSAParameters rsaParams = new RSAParameters
                  {
                      Modulus = p.Modulus.ToByteArrayUnsigned(),
                      Exponent = p.Exponent.ToByteArrayUnsigned()
                  };
                  rsa.ImportParameters(rsaParams);
                  return rsa.ToXmlString(false);
              }
          }
      }

   

C#实现RSA加密解密

原文：https://www.cnblogs.com/caiyt/p/12088745.html