NetCore 下使用RSA加密，解密；并且前端使用jsencrypt.js实现Rsa相关方法。

首先上资源

jsencrypt.js下载地址：https://github.com/travist/jsencrypt

第三方Rsa密钥生成工具：BouncyCastle.Crypto.dll，直接可以在NuGet中查找。

至于为什么用第三方工具生成密钥，是为了和jsencrypt配合。c#本身RSACryptoServiceProvider类生成的工具不能再jsencrypt中使用。

有关知识：http://www.cnblogs.com/dudu/p/dotnet-core-rsa-openssl.html

并且：（信息来源：https://www.jianshu.com/p/f22b4e565ec1）文中的生成RSAParameters方法来源于此。

• RSACryptoServiceProvider
  在Windows 环境下依然可以使用RSACryptoServiceProvider, 但在Linux 环境下编译不过. 参考 dudu 的文章 .net core中使用openssl的公钥私钥进行加解密

• FromXmlString方法和ToXmlString
  由于不在使用RSACryptoServiceProvider这两个方法不在提供,我们可以通过扩展方法来添加这两个方法,以处理C#生成的密钥.

这边引用BouncyCastle.Crypto.dll会在NuGet里有个警告提示，如图：

我在Centos7，和windows10 里测试过，可以使用，其他就不懂了。

这是BouncyCastle.Crypto.dll在NuGet相关信息:

好了开始上代码。

使用BouncyCastle.Crypto.dll生成PEM密钥字符串

            public static RSAKey GetKey()
            {
                var key = new RSAKey();
                Org.BouncyCastle.Crypto.Generators.RsaKeyPairGenerator g = new Org.BouncyCastle.Crypto.Generators.RsaKeyPairGenerator();
                g.Init(new Org.BouncyCastle.Crypto.KeyGenerationParameters(new SecureRandom(), 1024));
                var pair = g.GenerateKeyPair();



                TextWriter textWriter = new StringWriter();
                PemWriter pemWriter = new PemWriter(textWriter);
                pemWriter.WriteObject(pair.Private);
                pemWriter.Writer.Flush();

                string privateKey = textWriter.ToString();
                key.privateKey = privateKey;


                TextWriter textpubWriter = new StringWriter();
                PemWriter pempubWriter = new PemWriter(textpubWriter);
                pempubWriter.WriteObject(pair.Public);
                pempubWriter.Writer.Flush();
                string pubKey = textpubWriter.ToString();
                key.publicKey = pubKey;



                #region 使用该部分代码偶尔会在解析私钥时候发生“不正常数据”异常。
                //PrivateKeyInfo privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(pair.Private);
                //byte[] serializedPrivateBytes = privateKeyInfo.ToAsn1Object().GetDerEncoded();
                //key.privateKey = Convert.ToBase64String(serializedPrivateBytes);//PEM秘钥

                //SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(pair.Public);
                //byte[] serializedPublicBytes = publicKeyInfo.ToAsn1Object().GetDerEncoded();
                //key.publicKey = Convert.ToBase64String(serializedPublicBytes);//PEM公钥 
                #endregion

                return key;
            }

 然后是将字符串转换为Pem密钥

            #region 解析
            private static RSAParameters CreateRsaFromPrivateKey(string privateKey)
            {
                string tmp = privateKey.Replace("
", "").Replace("-----END RSA PRIVATE KEY-----", "").Replace("-----BEGIN RSA PRIVATE KEY-----", "");
                var privateKeyBits = System.Convert.FromBase64String(tmp);
                var RSAparams = new RSAParameters();

                using (var 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));
                }
                return RSAparams;
            }

            private static 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 static RSAParameters CreateRsaFromPublicKey(string publicKeyString)
            {
                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;

                var tmp = publicKeyString.Replace("-----BEGIN PUBLIC KEY-----", "").Replace("-----END PUBLIC KEY-----", "").Replace("
", "");

                x509key = Convert.FromBase64String(tmp);
                x509size = x509key.Length;

                using (var mem = new MemoryStream(x509key))
                {
                    using (var binr = new BinaryReader(mem))
                    {
                        byte bt = 0;
                        ushort twobytes = 0;

                        twobytes = binr.ReadUInt16();
                        if (twobytes == 0x8130)
                            binr.ReadByte();
                        else if (twobytes == 0x8230)
                            binr.ReadInt16();
                        else
                            return new RSAParameters();

                        seq = binr.ReadBytes(15);
                        if (!CompareBytearrays(seq, SeqOID))
                            return new RSAParameters();

                        twobytes = binr.ReadUInt16();
                        if (twobytes == 0x8103)
                            binr.ReadByte();
                        else if (twobytes == 0x8203)
                            binr.ReadInt16();
                        else
                            return new RSAParameters();

                        bt = binr.ReadByte();
                        if (bt != 0x00)
                            return new RSAParameters();

                        twobytes = binr.ReadUInt16();
                        if (twobytes == 0x8130)
                            binr.ReadByte();
                        else if (twobytes == 0x8230)
                            binr.ReadInt16();
                        else
                            return new RSAParameters();

                        twobytes = binr.ReadUInt16();
                        byte lowbyte = 0x00;
                        byte highbyte = 0x00;

                        if (twobytes == 0x8102)
                            lowbyte = binr.ReadByte();
                        else if (twobytes == 0x8202)
                        {
                            highbyte = binr.ReadByte();
                            lowbyte = binr.ReadByte();
                        }
                        else
                            return new RSAParameters();
                        byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };
                        int modsize = BitConverter.ToInt32(modint, 0);

                        int firstbyte = binr.PeekChar();
                        if (firstbyte == 0x00)
                        {
                            binr.ReadByte();
                            modsize -= 1;
                        }

                        byte[] modulus = binr.ReadBytes(modsize);

                        if (binr.ReadByte() != 0x02)
                            return new RSAParameters();
                        int expbytes = (int)binr.ReadByte();
                        byte[] exponent = binr.ReadBytes(expbytes);
                        var rsaKeyInfo = new RSAParameters
                        {
                            Modulus = modulus,
                            Exponent = exponent
                        };
                        return rsaKeyInfo;
                    }

                }
            }

            private static 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;
            } 
            #endregion

C#后端加密解密方法

            //RSA加密
            public static string RSAEncrypt(string context, string publicKey)
            {
                UTF8Encoding ByteConverter = new UTF8Encoding();
                byte[] DataToEncrypt = ByteConverter.GetBytes(context);
                try
                {
                    var rsa = RSA.Create();
                    rsa.ImportParameters(CreateRsaFromPublicKey(publicKey));

                    byte[] bytes = rsa.Encrypt(DataToEncrypt, RSAEncryptionPadding.Pkcs1);
                    string str = Convert.ToBase64String(bytes);
                    return str;
                }
                catch (CryptographicException e)
                {
                    throw e;
                }
            }

            //RSA解密
            public static string RSADecrypt(string context, string privateKey)
            {
                byte[] DataToDecrypt = Convert.FromBase64String(context);
                try
                {
                    var rsa = RSA.Create();
                    rsa.ImportParameters(CreateRsaFromPrivateKey(privateKey));

                    byte[] bytes = rsa.Decrypt(DataToDecrypt, RSAEncryptionPadding.Pkcs1);
                    UTF8Encoding ByteConverter = new UTF8Encoding();
                    string str = ByteConverter.GetString(bytes);
                    return str;
                }
                catch (CryptographicException e)
                {
                    return null;
                    throw e;
                }
            }

ok以上就是后端代码。

前段代码就简单了，这个是jsencrypt官方的demo。

<!doctype html>
<html>
  <head>
    <title>JavaScript RSA Encryption</title>
    <script src="http://code.jquery.com/jquery-1.8.3.min.js"></script>
    <script src="bin/jsencrypt.min.js"></script>
    <script type="text/javascript">

      // Call this code when the page is done loading.
      $(function() {

        // Run a quick encryption/decryption when they click.
        $('#testme').click(function() {

          // Encrypt with the public key...
          var encrypt = new JSEncrypt();
          encrypt.setPublicKey($('#pubkey').val());
          var encrypted = encrypt.encrypt($('#input').val());

          // Decrypt with the private key...
          var decrypt = new JSEncrypt();
          decrypt.setPrivateKey($('#privkey').val());
          var uncrypted = decrypt.decrypt(encrypted);

          // Now a simple check to see if the round-trip worked.
          if (uncrypted == $('#input').val()) {
            alert('It works!!!');
          }
          else {
            alert('Something went wrong....');
          }
        });
      });
    </script>
  </head>
  <body>
    <label for="privkey">Private Key</label><br/>
    <textarea id="privkey" rows="15" cols="65">-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----</textarea><br/>
    <label for="pubkey">Public Key</label><br/>
    <textarea id="pubkey" rows="15" cols="65">-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDlOJu6TyygqxfWT7eLtGDwajtN
FOb9I5XRb6khyfD1Yt3YiCgQWMNW649887VGJiGr/L5i2osbl8C9+WJTeucF+S76
xFxdU6jE0NQ+Z+zEdhUTooNRaY5nZiu5PgDB0ED/ZKBUSLKL7eibMxZtMlUDHjm4
gwQco1KRMDSmXSMkDwIDAQAB
-----END PUBLIC KEY-----</textarea><br/>
    <label for="input">Text to encrypt:</label><br/>
    <textarea id="input" name="input" type="text" rows=4 cols=70>This is a test!</textarea><br/>
    <input id="testme" type="button" value="Test Me!!!" /><br/>
  </body>
</html>

打完，收功，希望能给大家带来一点用处^_^