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。
-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC0w036ClSD0LvxPROMun0u022R
OJlZE6P3m+gjq3gpi4n7lo8jhTqMqgccDbVJqnIfMzWS9O3lnlQXWTxJ3B4XJ52F
AcriY5brOXUVgBLx5QMHLLd1gtJnmG4i7r4ytgX7XVKRnojR6zca1YnS0lbGGDF1
CGllB1riNrdksSQP+wIDAQAB
-----END PUBLIC KEY-----
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
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 / - ;//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, , MaxBlockSize); while (BlockSize > )
{
Byte[] ToEncrypt = new Byte[BlockSize];
Array.Copy(Buffer, , ToEncrypt, , BlockSize); Byte[] Cryptograph = _publicKeyRsaProvider.Encrypt(ToEncrypt, false);
CrypStream.Write(Cryptograph, , Cryptograph.Length); BlockSize = PlaiStream.Read(Buffer, , MaxBlockSize);
} return Convert.ToBase64String(CrypStream.ToArray(), Base64FormattingOptions.None);
}
} } private string Decrypt2(string ciphertext)
{ Byte[] CiphertextData = Convert.FromBase64String(ciphertext);
int MaxBlockSize = _privateKeyRsaProvider.KeySize / ; //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, , MaxBlockSize); while (BlockSize > )
{
Byte[] ToDecrypt = new Byte[BlockSize];
Array.Copy(Buffer, , ToDecrypt, , BlockSize); Byte[] Plaintext = _privateKeyRsaProvider.Decrypt(ToDecrypt, false);
PlaiStream.Write(Plaintext, , Plaintext.Length); BlockSize = CrypStream.Read(Buffer, , 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 = ;
ushort twobytes = ;
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 = ;
byte lowbyte = 0x00;
byte highbyte = 0x00;
int count = ;
bt = binr.ReadByte();
if (bt != 0x02)
return ;
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, );
}
else
{
count = bt;
} while (binr.ReadByte() == 0x00)
{
count -= ;
}
binr.BaseStream.Seek(-, 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[];
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 = ;
ushort twobytes = ; 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(); //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, ); 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 -= ; //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 = ;
foreach (byte c in a)
{
if (c != b[i])
return false;
i++;
}
return true;
}
}
}
虽然将公钥暴露在js文件中，但是如果需要解密得到明文，必须需要私钥（这个存储在后台，不容易获取）。
调试运行，可以看到获取的密码是加密后的数据，然后在后台可以进行解密获取到明文。