在分享源码之前，先准备一些东西：
1、下载一个js加密帮助文件，下载地址：https://passport.cnblogs.com/scripts/jsencrypt.min.js，在项目中以JavaScript.js保存，以方便引用：，当然了，也可以直接引用网页的，即：
2、生成一对RSA密钥对，可以在这个网址生成：http://web.chacuo.net/netrsakeypair，也可以下载一个工具来生成。
3、创建一个JsEncryptHelper.cs，包含后台的加密和解决功能，要把第2步生成的密钥对放置在此文件中，之前本来想在前台js中有参调用加密函数来加密不成功，就是我楼上提出的问题。后面就采用JavaScript.js够进行加密了，为了展示效果，把加密的结果保存在文本框中，如果在实际项目中可以把密文保存在一个隐藏的文本框中。后面会把这个类JsEncryptHelper.cs的代码一并分享。
一、前台代码：
二、后台解密按钮代码 ：
protected void Button1_Click(object sender, EventArgs e)
{
JsEncryptHelper newRSA = new JsEncryptHelper();
mingwen.Text = newRSA.Decrypt(miwen.Text);
}
三、JsEncryptHelper.cs代码：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
///
/// JsEncryptHelper 的摘要说明
///
///
/// AJax提交参数加密帮助类
///
public class JsEncryptHelper
{
private const string defaultprivateKey = @"MIICXAIBAAKBgQCC0hrRIjb3noDWNtbDpANbjt5Iwu2NFeDwU16Ec87ToqeoIm2K
I+cOs81JP9aTDk/jkAlU97mN8wZkEMDr5utAZtMVht7GLX33Wx9XjqxUsDfsGkqN
L8dXJklWDu9Zh80Ui2Ug+340d5dZtKtd+nv09QZqGjdnSp9PTfFDBY133QIDAQAB
AoGAJBNTOITaP6LCyKVKyEdnHaKNAz0DS+V9UwjKhyAgfcAxwm3sDdd6FQCEW0TI
JA7Np7rFYrGwcR1UOoKxkNxB10ACl6JX4rE7xKS6NLZumdwxON/KgDb+2SQtWEXD
gBySZ7Znv/FhEp1RmoBDjZ05E99kILWO3ToorUM0Eq2GHQkCQQCnUMXgZa4HS0tu
INzysgB37d7ene9+CIARyJphs079qao2UWCgXqen43Ob6GJUgulz7We+4JOZFld0
TfEi1E5rAkEAyClQAVzafLO3gXgqH7tbRbPPx788+4opxT9QBo2Trzl6/3FlcC1P
IZeqbQ/Oc2wT7jmidFnpyTEnM2p7Yq3U1wJBAILTWaX4W3dAnJ5j+9+Y51zfFiEj
hRwbMWi2XmB+gAlAHOOUBeXfnWBdLQx/TEOgiUIoI7LQjxhoq8E5II+HSjkCQDlK
SdH6B7dFoTJ3eGcYsykiLEiZ3hSJGSeR1Y/qmei/ZQsUI9qVvV56EJeivI6g0puO
94ah7Z5eaT/4LFS0OIUCQDgLn586pGgeidLhQsIe/AR3y9YOCAygTFLxzmeBXOKt
M90q4516KWlTtK2u99442mNi7hNmjryBVwk62foWo8w=";
private const string defaultpublicKey = @"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCC0hrRIjb3noDWNtbDpANbjt5I
wu2NFeDwU16Ec87ToqeoIm2KI+cOs81JP9aTDk/jkAlU97mN8wZkEMDr5utAZtMV
ht7GLX33Wx9XjqxUsDfsGkqNL8dXJklWDu9Zh80Ui2Ug+340d5dZtKtd+nv09QZq
GjdnSp9PTfFDBY133QIDAQAB";
private RSACryptoServiceProvider _privateKeyRsaProvider;
private RSACryptoServiceProvider _publicKeyRsaProvider;
public JsEncryptHelper(string privateKey = "", string publicKey = "")
{
if (string.IsNullOrEmpty(privateKey))
{
privateKey = defaultprivateKey;
}
if (string.IsNullOrEmpty(publicKey))
{
publicKey = defaultpublicKey;
}
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");
}
if (string.IsNullOrEmpty(cipherText))
{
return "";
}
return Encoding.UTF8.GetString(_privateKeyRsaProvider.Decrypt(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;
}
}