前言

前不久移植了支付宝官方的SDK，以适用ASP.NET Core使用支付宝支付，但是最近有好几位用户反应在Linux下使用会出错，调试发现是RSA加密的错误，下面具体讲一讲。

RSA在.NET Core的改动

以前我们使用RSA加密主要是使用RSACryptoServiceProvider这个类，在.NET Core中也有这个类，但是这个类并不支持跨平台，所以如果你是用这个类来进行加/解密在windows上运行是完全没有错误的，但是只要你一放到Linux下就会出现异常。

查阅资料得知，要解决这个问题，需要改用 System.Security.Cryptography.RSA.Create() 工厂方法，使用它之后，在 Windows 上创建的是 System.Security.Cryptography.RSACng 的实例，在 Mac 与 Linux 上创建的是 System.Security.Cryptography.RSAOpenSsl 的实例，它们都继承自 System.Security.Cryptography.RSA 抽象类。

RSACng：

相关资料：https://docs.microsoft.com/zh-cn/dotnet/api/system.security.cryptography.rsacng?view=netcore-2.0

RSAOpenSsl ：

相关资料：https://docs.microsoft.com/zh-cn/dotnet/api/system.security.cryptography.rsaopenssl?view=netcore-2.0

在Windows上的调试截图：

在Mac上使用Visual studio For Mac 调试截图：

RSA公钥/私钥说明

这里的RSA加密/解密主要是针对于由OpenSSL生成的公钥/私钥字符串。ssh-keygen -t rsa 命令生成的公钥私钥是不行的。

公钥示例：

私钥示例：

公钥/私钥生成

Windows&MAC_OSX可以使用有支付宝开发的RSA密钥生成工具：

使用此工具生成的时候一定要选择，PKCS1

下载地址：https://doc.open.alipay.com/docs/doc.htm?treeId=291&articleId=105971&docType=1

此外还可以使用OpenSSL工具命令来生成：https://doc.open.alipay.com/docs/doc.htm?articleId=106130&docType=1

.NET Core 中的使用

这里要讲一下RSA2算法。

什么是RSA2 ？RSA2 是在原来SHA1WithRSA签名算法的基础上，新增了支持SHA256WithRSA的签名算法。该算法比SHA1WithRSA有更强的安全能力。

算法名称	标准签名算法名称	备注
RSA2	SHA256WithRSA	（强烈推荐使用），强制要求RSA密钥的长度至少为2048
RSA	SHA1WithRSA	对RSA密钥的长度不限制，推荐使用2048位以上

签名的作用:保证数据完整性,机密性和发送方角色的不可抵赖性

这里来一发干货，我已经封装好的RSA/RSA2算法，支持加密/解密/签名/验证签名。

/// <summary>
/// RSA加解密 使用OpenSSL的公钥加密/私钥解密
/// 作者：李志强
/// 创建时间：2017年10月30日15:50:14
/// QQ:501232752
/// </summary>

public class RSAHelper{   
  private readonly RSA _privateKeyRsaProvider;  
  private readonly RSA _publicKeyRsaProvider;  
  private readonly HashAlgorithmName _hashAlgorithmName;   
  
  private readonly Encoding _encoding;    /// <summary>/// 实例化RSAHelper/// </summary>/// <param name="rsaType">加密算法类型 RSA SHA1;RSA2 SHA256 密钥长度至少为2048</param>/// <param name="encoding">编码类型</param>/// <param name="privateKey">私钥</param>/// <param name="publicKey">公钥</param>public RSAHelper(RSAType rsaType, Encoding encoding, string privateKey, string publicKey = null)    {_encoding = encoding;       
 if (!string.IsNullOrEmpty(privateKey)){_privateKeyRsaProvider = CreateRsaProviderFromPrivateKey(privateKey);}        if (!string.IsNullOrEmpty(publicKey)){_publicKeyRsaProvider = CreateRsaProviderFromPublicKey(publicKey);}_hashAlgorithmName = rsaType == RSAType.RSA ? HashAlgorithmName.SHA1 : HashAlgorithmName.SHA256;}    #region 使用私钥签名/// <summary>/// 使用私钥签名/// </summary>/// <param name="data">原始数据</param>/// <returns></returns>public string Sign(string data)    {     
   byte[] dataBytes = _encoding.GetBytes(data);    
       var signatureBytes = _privateKeyRsaProvider.SignData(dataBytes, _hashAlgorithmName, RSASignaturePadding.Pkcs1);   
            return Convert.ToBase64String(signatureBytes);}    #endregion#region 使用公钥验证签名/// <summary>/// 使用公钥验证签名/// </summary>/// <param name="data">原始数据</param>/// <param name="sign">签名</param>/// <returns></returns>public bool Verify(string data,string sign)    {    
    byte[] dataBytes = _encoding.GetBytes(data);      
      byte[] signBytes = Convert.FromBase64String(sign);  
      var verify = _publicKeyRsaProvider.VerifyData(dataBytes, signBytes, _hashAlgorithmName, RSASignaturePadding.Pkcs1);       
       return verify;}    #endregion#region 解密public string Decrypt(string cipherText)    {        if (_privateKeyRsaProvider == null){         
   throw new Exception("_privateKeyRsaProvider is null");}       
    return Encoding.UTF8.GetString(_privateKeyRsaProvider.Decrypt(Convert.FromBase64String(cipherText), RSAEncryptionPadding.Pkcs1));}    #endregion#region 加密public string Encrypt(string text)    {      
      if (_publicKeyRsaProvider == null){           
       throw new Exception("_publicKeyRsaProvider is null");}       
        return Convert.ToBase64String(_publicKeyRsaProvider.Encrypt(Encoding.UTF8.GetBytes(text), RSAEncryptionPadding.Pkcs1));}    #endregion#region 使用私钥创建RSA实例public RSA CreateRsaProviderFromPrivateKey(string privateKey)    {        var privateKeyBits = Convert.FromBase64String(privateKey);     
           var rsa = RSA.Create();       
           var rsaParameters = 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()");rsaParameters.Modulus = binr.ReadBytes(GetIntegerSize(binr));rsaParameters.Exponent = binr.ReadBytes(GetIntegerSize(binr));rsaParameters.D = binr.ReadBytes(GetIntegerSize(binr));rsaParameters.P = binr.ReadBytes(GetIntegerSize(binr));rsaParameters.Q = binr.ReadBytes(GetIntegerSize(binr));rsaParameters.DP = binr.ReadBytes(GetIntegerSize(binr));rsaParameters.DQ = binr.ReadBytes(GetIntegerSize(binr));rsaParameters.InverseQ = binr.ReadBytes(GetIntegerSize(binr));}rsa.ImportParameters(rsaParameters);     
       return rsa;}    #endregion#region 使用公钥创建RSA实例public RSA 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[] seq = new byte[15];      
      var x509Key = Convert.FromBase64String(publicKeyString);        // ---------  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 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 -----                var rsa = RSA.Create();                RSAParameters rsaKeyInfo = new RSAParameters                {                    Modulus = modulus,                    Exponent = exponent                };                rsa.ImportParameters(rsaKeyInfo);         
               return rsa;            }        }    }    #endregion    #region 导入密钥算法    private int GetIntegerSize(BinaryReader binr)    {       
 byte bt = 0;        int count = 0;        bt = binr.ReadByte();    
     if (bt != 0x02)          
       return 0;        bt = binr.ReadByte();      
         if (bt == 0x81)            count = binr.ReadByte();   
         else        if (bt == 0x82)        {      
               var highbyte = binr.ReadByte();  
               var 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 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}
/// <summary>
/// RSA算法类型
/// </summary>

public enum RSAType {   
     /// <summary>    /// SHA1    /// </summary>    RSA = 0,    /// <summary>    /// RSA2 密钥长度至少为2048    /// SHA256    /// </summary>    RSA2 }

使用：

static void Main(string[] args){    //2048 公钥string publicKey =        "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAoQh0wEqx/R2H1v00IU12Oc30fosRC/frhH89L6G+fzeaqI19MYQhEPMU13wpeqRONCUta+2iC1sgCNQ9qGGf19yGdZUfueaB1Nu9rdueQKXgVurGHJ+5N71UFm+OP1XcnFUCK4wT5d7ZIifXxuqLehP9Ts6sNjhVfa+yU+VjF5HoIe69OJEPo7OxRZcRTe17khc93Ic+PfyqswQJJlY/bgpcLJQnM+QuHmxNtF7/FpAx9YEQsShsGpVo7JaKgLo+s6AFoJ4QldQKir2vbN9vcKRbG3piElPilWDpjXQkOJZhUloh/jd7QrKFimZFldJ1r6Q59QYUyGKZARUe0KZpMQIDAQAB";    //2048 私钥string privateKey =        "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";    var rsa = new RSAHelper(RSAType.RSA2,Encoding.UTF8, privateKey, publicKey);    string str = "博客园 http://www.cnblogs.com/";Console.WriteLine("原始字符串："+str);    //加密string enStr = rsa.Encrypt(str);Console.WriteLine("加密字符串："+enStr);    //解密string deStr = rsa.Decrypt(enStr);Console.WriteLine("解密字符串："+deStr);    //私钥签名string signStr = rsa.Sign(str);Console.WriteLine("字符串签名：" + signStr);    //公钥验证签名bool signVerify = rsa.Verify(str,signStr);Console.WriteLine("验证签名：" + signVerify);Console.ReadKey();
}