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）

这篇文章主要给大家介绍了关于同时兼容JS和C#的RSA加密解密算法，通过该算法可以对web提交的数据进行加密传输，文中通过图文及示例代码介绍的非常详细，需要的朋友们可以参考借鉴，下面来一起看看吧。

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

 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; ///  /// RSA解密 /// 
 ///  ///  public string Decrypt(string cipherText) { if (_privateKeyRsaProvider == null) { throw new Exception("_privateKeyRsaProvider is null"); } return Decrypt2(cipherText); } ///  /// RSA加密 /// 
 ///  ///  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; } } }