RSA分段加密解密

1 1 private static readonly Encoding Encoder = Encoding.UTF8;
2 2 
3 3         public static String Encrypt(this String plaintext)
4 4         {
5 5             X509Certificate2 _X509Certificate2 = RSAHelper.RetrieveX509Certificate();
6 6             string publickey = @"<RSAKeyValue><Modulus>5m9m14XH3oqLJ8bNGw9e4rGpXpcktv9MSkHSVFVMjHbfv+SJ5v0ubqQxa5YjLN4vc49z7SVju8s0X4gZ6AzZTn06jzWOgyPRV54Q4I0DCYadWW4Ze3e+BOtwgVU1Og3qHKn8vygoj40J6U85Z/PTJu3hN1m75Zr195ju7g9v4Hk=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
7 7             using (RSACryptoServiceProvider RSACryptography = /*_X509Certificate2.PublicKey.Key as*/ new RSACryptoServiceProvider())
8 8             {
9 9                 RSACryptography.FromXmlString(publickey);
1010                 Byte[] PlaintextData = RSAHelper.Encoder.GetBytes(plaintext);
1111                 int MaxBlockSize = RSACryptography.KeySize / 8 - 11;    //加密块最大长度限制
1212 
1313                 if (PlaintextData.Length <= MaxBlockSize)
1414                     return Convert.ToBase64String(RSACryptography.Encrypt(PlaintextData, false));
1515 
1616                 using (MemoryStream PlaiStream = new MemoryStream(PlaintextData))
1717                 using (MemoryStream CrypStream = new MemoryStream())
1818                 {
1919                     Byte[] Buffer = new Byte[MaxBlockSize];
2020                     int BlockSize = PlaiStream.Read(Buffer, 0, MaxBlockSize);
2121 
2222                     while (BlockSize > 0)
2323                     {
2424                         Byte[] ToEncrypt = new Byte[BlockSize];
2525                         Array.Copy(Buffer, 0, ToEncrypt, 0, BlockSize);
2626 
2727                         Byte[] Cryptograph = RSACryptography.Encrypt(ToEncrypt, false);
2828                         CrypStream.Write(Cryptograph, 0, Cryptograph.Length);
2929 
3030                         BlockSize = PlaiStream.Read(Buffer, 0, MaxBlockSize);
3131                     }
3232 
3333                     return Convert.ToBase64String(CrypStream.ToArray(), Base64FormattingOptions.None);
3434                 }
3535             }
3636         }
3737 
3838         public static String Decrypt(this String ciphertext)
3939         {
4040             X509Certificate2 _X509Certificate2 = RSAHelper.RetrieveX509Certificate();
4141             string privatekey = @"<RSAKeyValue><Modulus>5m9m14XH3oqLJ8bNGw9e4rGpXpcktv9MSkHSVFVMjHbfv+SJ5v0ubqQxa5YjLN4vc49z7SVju8s0X4gZ6AzZTn06jzWOgyPRV54Q4I0DCYadWW4Ze3e+BOtwgVU1Og3qHKn8vygoj40J6U85Z/PTJu3hN1m75Zr195ju7g9v4Hk=</Modulus><Exponent>AQAB</Exponent><P>/hf2dnK7rNfl3lbqghWcpFdu778hUpIEBixCDL5WiBtpkZdpSw90aERmHJYaW2RGvGRi6zSftLh00KHsPcNUMw==</P><Q>6Cn/jOLrPapDTEp1Fkq+uz++1Do0eeX7HYqi9rY29CqShzCeI7LEYOoSwYuAJ3xA/DuCdQENPSoJ9KFbO4Wsow==</Q><DP>ga1rHIJro8e/yhxjrKYo/nqc5ICQGhrpMNlPkD9n3CjZVPOISkWF7FzUHEzDANeJfkZhcZa21z24aG3rKo5Qnw==</DP><DQ>MNGsCB8rYlMsRZ2ek2pyQwO7h/sZT8y5ilO9wu08Dwnot/7UMiOEQfDWstY3w5XQQHnvC9WFyCfP4h4QBissyw==</DQ><InverseQ>EG02S7SADhH1EVT9DD0Z62Y0uY7gIYvxX/uq+IzKSCwB8M2G7Qv9xgZQaQlLpCaeKbux3Y59hHM+KpamGL19Kg==</InverseQ><D>vmaYHEbPAgOJvaEXQl+t8DQKFT1fudEysTy31LTyXjGu6XiltXXHUuZaa2IPyHgBz0Nd7znwsW/S44iql0Fen1kzKioEL3svANui63O3o5xdDeExVM6zOf1wUUh/oldovPweChyoAdMtUzgvCbJk1sYDJf++Nr0FeNW1RB1XG30=</D></RSAKeyValue>";
4242             using (RSACryptoServiceProvider RSACryptography = /*_X509Certificate2.PrivateKey as*/ new RSACryptoServiceProvider())
4343             {
4444                 RSACryptography.FromXmlString(privatekey);
4545                 Byte[] CiphertextData = Convert.FromBase64String(ciphertext);
4646                 int MaxBlockSize = RSACryptography.KeySize / 8;    //解密块最大长度限制
4747 
4848                 if (CiphertextData.Length <= MaxBlockSize)
4949                     return RSAHelper.Encoder.GetString(RSACryptography.Decrypt(CiphertextData, false));
5050 
5151                 using (MemoryStream CrypStream = new MemoryStream(CiphertextData))
5252                 using (MemoryStream PlaiStream = new MemoryStream())
5353                 {
5454                     Byte[] Buffer = new Byte[MaxBlockSize];
5555                     int BlockSize = CrypStream.Read(Buffer, 0, MaxBlockSize);
5656 
5757                     while (BlockSize > 0)
5858                     {
5959                         Byte[] ToDecrypt = new Byte[BlockSize];
6060                         Array.Copy(Buffer, 0, ToDecrypt, 0, BlockSize);
6161 
6262                         Byte[] Plaintext = RSACryptography.Decrypt(ToDecrypt, false);
6363                         PlaiStream.Write(Plaintext, 0, Plaintext.Length);
6464 
6565                         BlockSize = CrypStream.Read(Buffer, 0, MaxBlockSize);
6666                     }
6767 
6868                     return RSAHelper.Encoder.GetString(PlaiStream.ToArray());
6969                 }
7070             }
7171         }
7272 
7373         private static X509Certificate2 RetrieveX509Certificate()
7474         {
7575 
7676             return null;    //检索用于 RSA 加密的 X509Certificate2 证书
7777         }

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