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1. 前言
本问是根据网上很多文章的总结得到的。
2. 介绍
RSA加密算法是一种非对称加密算法。
对极大整数做因数分解的难度决定了RSA算法的可靠性。换言之，对一极大整数做因数分解愈困难，RSA算法愈可靠。假如有人找到一种快速因数分解的算法的话，那么用RSA加密的信息的可靠性就肯定会极度下降。但找到这样的算法的可能性是非常小的。今天只有短的RSA钥匙才可能被强力方式解破。到2016年为止，世界上还没有任何可靠的攻击RSA算法的方式。只要其钥匙的长度足够长，用RSA加密的信息实际上是不能被解破的。
1983年麻省理工学院在美国为RSA算法申请了专利。这个专利2000年9月21日失效。由于该算法在申请专利前就已经被发表了，在世界上大多数其它地区这个专利权不被承认。
3. 开始
1）在线RSA加密，请选用PKCS#1来生成公钥与私钥
http://web.chacuo.net/netrsakeypair
点击【生成秘钥对RSA】就可以生成对应的非对称加密公钥与非对称加密似钥
2）前端JS框架
http://travistidwell.com/jsencrypt/
3）流程图
从上图可以看到，先从网站上生成publicKey与privateKey。
第一步返回publicKey前端，用来对password等敏感字段的加密。
第二步，前端进行password敏感字段的加密。
第三步post数据给后端。
第四步用publicKey与privateKey进行解密。
4.代码
这里的代码是简单的直接从前端访问后台，后台进行解密。逻辑根据读者的爱好编写。
前端代码
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
<script src="http://code.jquery.com/jquery-1.8.3.min.js"></script>
<script src="http://passport.cnblogs.com/scripts/jsencrypt.min.js"></script>
<script type="text/javascript">
// 使用jsencrypt类库加密js方法，
function encryptRequest(reqUrl, data, publicKey) {
var encrypt = new JSEncrypt();
encrypt.setPublicKey(publicKey);
// ajax请求发送的数据对象
var sendData = new Object();
// 将data数组赋给ajax对象
for (var key in data) {
sendData[key] = encrypt.encrypt(data[key]);
}
$.ajax({
url: reqUrl,
type: ‘post‘,
data: sendData,
dataType: ‘json‘,
//contentType: ‘application/json; charset=utf-8‘,
success: function (data) {
console.info(data);
},
error: function (xhr) {
//console.error(‘出错了‘);
}
});
}
// Call this code when the page is done loading.
$(function () {
$(‘#testme‘).click(function () {
var data = [];
data[‘username‘] = $(‘#username‘).val();
data[‘passwd‘] = $(‘#passwd‘).val();
var pkey = $(‘#pubkey‘).val();
encryptRequest(‘/WebForm2.aspx‘, data, pkey);
});
});
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<label for="pubkey">Public Key</label><br />
<textarea id="pubkey" rows="15" cols="65">
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCDbrIgHK8qkz5IfK/A7At4SVZQ
31TalDPsc4vzeDVjd5ao46hcf+eOEQNm8jmxxHTm6WPSTy7RDVXG/NI489L9okkd
K++kVh2Z9GjBo5jw/n9EYojt8aYyEOc6cMHT2Fv+1smG+X/W2HeXXoJJjcFLSjBe
CKx1SoCD4+B2ZiDQ8wIDAQAB
</textarea><br />
<label for="input">Text to encrypt:</label><br />
name:<input id="username" name="username" type="text"></input><br />
password:<input id="passwd" name="passwd" type="password"></input><br />
<input id="testme" type="button" value="submit" /><br />
</div>
</form>
</body>
</html>
后端代码
解密
private RSACrypto rsaCrypto = new RSACrypto(PublicAttribute.PrivateKey, PublicAttribute.PublicKey); //获取参数 string usernameEncode = Request["username"]; string pwdEncode = Request["pwd"]; //解密 RSA string username = rsaCrypto.Decrypt(usernameEncode); string pwd = rsaCrypto.Decrypt(pwdEncode);
类 RSACrypto
public class RSACrypto { private RSACryptoServiceProvider _privateKeyRsaProvider; private RSACryptoServiceProvider _publicKeyRsaProvider; public RSACrypto(string privateKey, string publicKey = null) { if (!string.IsNullOrEmpty(privateKey)) { _privateKeyRsaProvider = CreateRsaProviderFromPrivateKey(privateKey); } if (!string.IsNullOrEmpty(publicKey)) { _publicKeyRsaProvider = CreateRsaProviderFromPublicKey(publicKey); } } public string Decrypt(string cipherText) { if (_privateKeyRsaProvider == null) { throw new Exception("_privateKeyRsaProvider is null"); } return Encoding.UTF8.GetString(_privateKeyRsaProvider.Decrypt(System.Convert.FromBase64String(cipherText), false)); } public string Encrypt(string text) { if (_publicKeyRsaProvider == null) { throw new Exception("_publicKeyRsaProvider is null"); } return Convert.ToBase64String(_publicKeyRsaProvider.Encrypt(Encoding.UTF8.GetBytes(text), false)); } 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; } }
到此结束了。
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原文地址：http://www.cnblogs.com/alunchen/p/5758585.html
