一、前台代码：

</div>
</form>

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();elsethrow 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();elseif (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 byteelse if (twobytes == 0x8230)binr.ReadInt16();   //advance 2 byteselsereturn null;seq = binr.ReadBytes(15);       //read the Sequence OIDif (!CompareBytearrays(seq, SeqOID))    //make sure Sequence for OID is correctreturn 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 byteelse if (twobytes == 0x8203)binr.ReadInt16();   //advance 2 byteselsereturn null;bt = binr.ReadByte();if (bt != 0x00)     //expect null byte nextreturn 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 byteelse if (twobytes == 0x8230)binr.ReadInt16();   //advance 2 byteselsereturn 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 moduluselse if (twobytes == 0x8202){highbyte = binr.ReadByte(); //advance 2 byteslowbyte = binr.ReadByte();}elsereturn null;byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };   //reverse byte order since asn.1 key uses big endian orderint modsize = BitConverter.ToInt32(modint, 0);int firstbyte = binr.PeekChar();if (firstbyte == 0x00){   //if first byte (highest order) of modulus is zero, don't include itbinr.ReadByte();    //skip this null bytemodsize -= 1;   //reduce modulus buffer size by 1}byte[] modulus = binr.ReadBytes(modsize);   //read the modulus bytesif (binr.ReadByte() != 0x02)            //expect an Integer for the exponent datareturn 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;
}

}
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