同时兼容JS和C#的RSA加密解密算法详解（对web提交的数据加密传输）

2020-01-24 00:34:00

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来源：转载

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前言

我们在Web应用中往往涉及到敏感的数据，由于HTTP协议以明文的形式与服务器进行交互，因此可以通过截获请求的数据包进行分析来盗取有用的信息。虽然https可以对传输的数据进行加密，但是必须要申请证书（一般都是收费的），成本较高。那么问题来了，如果对web提交的敏感数据进行加密呢？web应用中，前端的数据处理和交互基本上都是靠javascript来完成，后台的逻辑处理可以C#(java)等进行处理。

微软的C#中虽然有RSA算法，但是格式和OpenSSL生成的公钥/私钥文件格式并不兼容。这个也给贯通前后台的RSA加密解密带来了难度。为了兼容OpenSSL生成的公钥/私钥文件格式，贯通javascript和C#的RSA加密解密算法，必须对C#内置的方法进行再度封装。

下面以登录为例，用户在密码框输入密码后，javascript发送ajax请求时，对密码先进行rsa加密后再发送，服务器接收到加密后的密码后，先对其进行解密，然后再验证登录是否成功。

1、为了进行RSA加密解密，首先需要用openssl生成一对公钥和私钥（没有的先下载openssl)：

1）打开openssl.exe文件，输入 genrsa -out openssl_rsa_priv.pem 1024

此命令在openssl.exe同目录下生成openssl_rsa_private_key.pem文件。

2）生成公钥 rsa -in openssl_rsa__private.pem -pubout -out openssl_rsa__public.pem

以上命令会创建如下的文件：

这个文件可以用文本编辑器进行打开，查看内容。

2、用jsencrypt对密码进行加密：

首先需要导入js包文件

<script src="dist/js/jsencrypt.js"></script>

var encrypt = new JSEncrypt();var pubkey = "-----BEGIN PUBLIC KEY----- / MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDAj0dPnBMf3Z4VT1B8Ee6bjKNs / hlYj7xvGijAa8RCdmGR7mrtrExnk8mdUlwdcS05gc4SSFOyWJcYtKUHpWn8/pkS0 / vgGOl9Bzn0Xt9hiqTb3pZAfykNrMDGZMgJgfD6KTnfzVUAOupvxjcGkcoj6/vV5I / eMcx8mT/z3elfsDSjQIDAQAB / -----END PUBLIC KEY-----";encrypt.setPublicKey(pubkey);var encrypted = encrypt.encrypt($('#txtpwd').val());//console.log(encrypted);$.ajax({ type: "POST", url: "http://localhost:24830/services/rsa_pem.ashx", data: { "pwd": encrypted }, dataType: "Json", error: function (xhr, status, error) {  // alert(error);  $("#txtInfo").text(' 请求服务器失败！');  $(that).text('登 录');  $(that).attr('disabled', false); }, success: function (json) {  if (uid == "admin" && json.data=="000") {  window.location.href = "index.html"; } else {  $("#txtInfo").text(' 用户名或者密码错误！');  $(that).text('登 录');  $(that).attr('disabled', false); } }});

3、后台用C#进行解密

using System;using System.Collections.Generic;using System.IO;using System.Linq;using System.Security.Cryptography;using System.Text;using System.Threading.Tasks;namespace CMCloud.SaaS{ public class RSACryptoService { private RSACryptoServiceProvider _privateKeyRsaProvider; private RSACryptoServiceProvider _publicKeyRsaProvider; /// <summary> /// RSA解密 /// </summary> /// <param name="cipherText"></param> /// <returns></returns> public string Decrypt(string cipherText) {  if (_privateKeyRsaProvider == null)  {  throw new Exception("_privateKeyRsaProvider is null");  }  return Decrypt2(cipherText); } /// <summary> /// RSA加密 /// </summary> /// <param name="text"></param> /// <returns></returns> public string Encrypt(string text) {  if (_publicKeyRsaProvider == null)  {  throw new Exception("_publicKeyRsaProvider is null");  }  return Encrypt2(text);  //return Convert.ToBase64String(_publicKeyRsaProvider.Encrypt(Encoding.UTF8.GetBytes(text), false)); } private string Encrypt2(string text) {  Byte[] PlaintextData = Encoding.UTF8.GetBytes(text);  int MaxBlockSize = _publicKeyRsaProvider.KeySize / 8 - 11;//加密块最大长度限制  if (PlaintextData.Length <= MaxBlockSize)  {  return Convert.ToBase64String(_publicKeyRsaProvider.Encrypt(PlaintextData, false));  }  else  {  using (MemoryStream PlaiStream = new MemoryStream(PlaintextData))  using (MemoryStream CrypStream = new MemoryStream())  {   Byte[] Buffer = new Byte[MaxBlockSize];   int BlockSize = PlaiStream.Read(Buffer, 0, MaxBlockSize);   while (BlockSize > 0)   {   Byte[] ToEncrypt = new Byte[BlockSize];   Array.Copy(Buffer, 0, ToEncrypt, 0, BlockSize);   Byte[] Cryptograph = _publicKeyRsaProvider.Encrypt(ToEncrypt, false);   CrypStream.Write(Cryptograph, 0, Cryptograph.Length);   BlockSize = PlaiStream.Read(Buffer, 0, MaxBlockSize);   }   return Convert.ToBase64String(CrypStream.ToArray(), Base64FormattingOptions.None);  }  } } private string Decrypt2(string ciphertext) {  Byte[] CiphertextData = Convert.FromBase64String(ciphertext);  int MaxBlockSize = _privateKeyRsaProvider.KeySize / 8; //解密块最大长度限制  if (CiphertextData.Length <= MaxBlockSize)  return System.Text.Encoding.UTF8.GetString(_privateKeyRsaProvider.Decrypt(CiphertextData, false));  using (MemoryStream CrypStream = new MemoryStream(CiphertextData))  using (MemoryStream PlaiStream = new MemoryStream())  {  Byte[] Buffer = new Byte[MaxBlockSize];  int BlockSize = CrypStream.Read(Buffer, 0, MaxBlockSize);  while (BlockSize > 0)  {   Byte[] ToDecrypt = new Byte[BlockSize];   Array.Copy(Buffer, 0, ToDecrypt, 0, BlockSize);   Byte[] Plaintext = _privateKeyRsaProvider.Decrypt(ToDecrypt, false);   PlaiStream.Write(Plaintext, 0, Plaintext.Length);   BlockSize = CrypStream.Read(Buffer, 0, MaxBlockSize);  }  return System.Text.Encoding.UTF8.GetString(PlaiStream.ToArray());  } } public RSACryptoService(string privateKey, string publicKey = null) {  if (!string.IsNullOrEmpty(privateKey))  {  _privateKeyRsaProvider = CreateRsaProviderFromPrivateKey(privateKey);  }  if (!string.IsNullOrEmpty(publicKey))  {  _publicKeyRsaProvider = CreateRsaProviderFromPublicKey(publicKey);  } }  private RSACryptoServiceProvider CreateRsaProviderFromPrivateKey(string privateKey) {  var privateKeyBits = System.Convert.FromBase64String(privateKey);  var RSA = new RSACryptoServiceProvider();  var RSAparams = new RSAParameters();  using (BinaryReader binr = new BinaryReader(new MemoryStream(privateKeyBits)))  {  byte bt = 0;  ushort twobytes = 0;  twobytes = binr.ReadUInt16();  if (twobytes == 0x8130)   binr.ReadByte();  else if (twobytes == 0x8230)   binr.ReadInt16();  else   throw new Exception("Unexpected value read binr.ReadUInt16()");  twobytes = binr.ReadUInt16();  if (twobytes != 0x0102)   throw new Exception("Unexpected version");  bt = binr.ReadByte();  if (bt != 0x00)   throw new Exception("Unexpected value read binr.ReadByte()");  RSAparams.Modulus = binr.ReadBytes(GetIntegerSize(binr));  RSAparams.Exponent = binr.ReadBytes(GetIntegerSize(binr));  RSAparams.D = binr.ReadBytes(GetIntegerSize(binr));  RSAparams.P = binr.ReadBytes(GetIntegerSize(binr));  RSAparams.Q = binr.ReadBytes(GetIntegerSize(binr));  RSAparams.DP = binr.ReadBytes(GetIntegerSize(binr));  RSAparams.DQ = binr.ReadBytes(GetIntegerSize(binr));  RSAparams.InverseQ = binr.ReadBytes(GetIntegerSize(binr));  }  RSA.ImportParameters(RSAparams);  return RSA; } private int GetIntegerSize(BinaryReader binr) {  byte bt = 0;  byte lowbyte = 0x00;  byte highbyte = 0x00;  int count = 0;  bt = binr.ReadByte();  if (bt != 0x02)  return 0;  bt = binr.ReadByte();  if (bt == 0x81)  count = binr.ReadByte();  else  if (bt == 0x82)  {  highbyte = binr.ReadByte();  lowbyte = binr.ReadByte();  byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };  count = BitConverter.ToInt32(modint, 0);  }  else  {  count = bt;  }  while (binr.ReadByte() == 0x00)  {  count -= 1;  }  binr.BaseStream.Seek(-1, SeekOrigin.Current);  return count; } private RSACryptoServiceProvider CreateRsaProviderFromPublicKey(string publicKeyString) {  // encoded OID sequence for PKCS #1 rsaEncryption szOID_RSA_RSA = "1.2.840.113549.1.1.1"  byte[] SeqOID = { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };  byte[] x509key;  byte[] seq = new byte[15];  int x509size;  x509key = Convert.FromBase64String(publicKeyString);  x509size = x509key.Length;  // --------- Set up stream to read the asn.1 encoded SubjectPublicKeyInfo blob ------  using (MemoryStream mem = new MemoryStream(x509key))  {  using (BinaryReader binr = new BinaryReader(mem)) //wrap Memory Stream with BinaryReader for easy reading  {   byte bt = 0;   ushort twobytes = 0;   twobytes = binr.ReadUInt16();   if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)   binr.ReadByte(); //advance 1 byte   else if (twobytes == 0x8230)   binr.ReadInt16(); //advance 2 bytes   else   return null;   seq = binr.ReadBytes(15); //read the Sequence OID   if (!CompareBytearrays(seq, SeqOID)) //make sure Sequence for OID is correct   return null;   twobytes = binr.ReadUInt16();   if (twobytes == 0x8103) //data read as little endian order (actual data order for Bit String is 03 81)   binr.ReadByte(); //advance 1 byte   else if (twobytes == 0x8203)   binr.ReadInt16(); //advance 2 bytes   else   return null;   bt = binr.ReadByte();   if (bt != 0x00) //expect null byte next   return null;   twobytes = binr.ReadUInt16();   if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)   binr.ReadByte(); //advance 1 byte   else if (twobytes == 0x8230)   binr.ReadInt16(); //advance 2 bytes   else   return null;   twobytes = binr.ReadUInt16();   byte lowbyte = 0x00;   byte highbyte = 0x00;   if (twobytes == 0x8102) //data read as little endian order (actual data order for Integer is 02 81)   lowbyte = binr.ReadByte(); // read next bytes which is bytes in modulus   else if (twobytes == 0x8202)   {   highbyte = binr.ReadByte(); //advance 2 bytes   lowbyte = binr.ReadByte();   }   else   return null;   byte[] modint = { lowbyte, highbyte, 0x00, 0x00 }; //reverse byte order since asn.1 key uses big endian order   int modsize = BitConverter.ToInt32(modint, 0);   int firstbyte = binr.PeekChar();   if (firstbyte == 0x00)   { //if first byte (highest order) of modulus is zero, don't include it   binr.ReadByte(); //skip this null byte   modsize -= 1; //reduce modulus buffer size by 1   }   byte[] modulus = binr.ReadBytes(modsize); //read the modulus bytes   if (binr.ReadByte() != 0x02)  //expect an Integer for the exponent data   return null;   int expbytes = (int)binr.ReadByte(); // should only need one byte for actual exponent data (for all useful values)   byte[] exponent = binr.ReadBytes(expbytes);   // ------- create RSACryptoServiceProvider instance and initialize with public key -----   RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();   RSAParameters RSAKeyInfo = new RSAParameters();   RSAKeyInfo.Modulus = modulus;   RSAKeyInfo.Exponent = exponent;   RSA.ImportParameters(RSAKeyInfo);   return RSA;  }  } } private bool CompareBytearrays(byte[] a, byte[] b) {  if (a.Length != b.Length)  return false;  int i = 0;  foreach (byte c in a)  {  if (c != b[i])   return false;  i++;  }  return true; } }}