.NET Core C#用RSACryptoServiceProvider解密Java RSA加密字符串报错

我正在开发一个C# .NET Core应用，需要解密由Java使用RSA/ECB/OAEPWithSHA-256AndMGF1Padding加密的字符串。尝试用RSACryptoServiceProvider解密时，一直抛出错误：Internal.Cryptography.CryptoThrowHelper.WindowsCryptographicException: 'Incorrect parameter'。已通过在线工具将PEM格式私钥转为XML格式，相关代码及密钥信息如下：

原代码 #

// encrypted string result is hello
const string encryptedString = "HhB77zNHCiB/CWa8v5VcaUNdi/M/mE9us8mQ4be1o2f3G/rQpsAcD8aue4QRJsOliekHIqaI9vrkyyLIDTJQDbkb15rweHZwwUr0YFqHFAq/PMt9tBph2U7n9zZN0zVDiFP/J4J8FZBGsLFx432YQP7DEi62fbHYY8fm1lXLx/Q=";
const string privateKey = "<RSAKeyValue><Modulus>utm7gcfK7JCTi1gRIcz2/BjtOpAAjqvd0uMKd2AAzxgFCEKCraPNKFjKv5OaEGq6bnbgt2BGx/5m5CrgjR26FMeA924QBoYZodGoSBV4klcoVihXtznWv96FYmuMya+BX5Q5fqM6TJ3iJbXI3+/o5eyblXj/mjjZ+yKGQjUn6Wc=</Modulus><Exponent>AQAB</Exponent><P>9+F18Oi6wKgCp4vSySDjKQmzIajs+QPsiOscmZxk/QV9T1Tg+QSi3s3sLxQFGnCU8Q0OE9d4idv6TLtS/ibl1w==</P><Q>wPiE2XzmTsEkOGO6KFfNHqkeh6uwd/WxHcRQgUfhFefl30YtIh1fj+Zq+b/rmzpkPPIVdl6zUbrWeldsfj2G8Q==</Q><DP>LyV52j1Zr+UExDtK9yhDLH4EzSUlFWPSrGQTh4AAkUNnBxy8wYBJPhlqj7W+Fr5NBeAWyl1UNtxZKhkC+wYI9w==</DP><DQ>ipw4uQxpVhqQDN09o6rl0OdD4commRRnY+1WsnZSLO0FBmsfEkktEm09XCZKc5bu14RAfGUrw0JEu14+tTM20Q==</DQ><InverseQ>7KvNQ83Bl1OFVOs4NZt2rFvPFQjSfSEdStyglsABSyBQUpC5IoJsj1SXrXQPPOFDgdDBXXsfJJRHEAl125CTmA==</InverseQ><D>UQkzODL1QCnnw4w7SeSBzY3l/PsNMtM5DkgnduRtFWP+crmdwT8EMBZqQDH8pFgVaOknxn/70qrz5srtvmYBGFjHdVRqBz01huykyIzxYhKATiljp+Akf72ljpIfs4zJ5bIQyA9OMYZKoIUjiUlCKBX29baxJ6tNAObOrwgAyGE=</D></RSAKeyValue>";
using (var rsa = new RSACryptoServiceProvider(1024))
{
    try
    {
        var base64Encrypted = encryptedString;

        // server decrypting data with private key                    
        rsa.FromXmlString(privateKey);

        var resultBytes = Convert.FromBase64String(base64Encrypted);
        var decryptedBytes = rsa.Decrypt(resultBytes, false);
        var decryptedData = Encoding.UTF8.GetString(decryptedBytes);
        Console.WriteLine(decryptedData.ToString());
    }
    finally
    {
        rsa.PersistKeyInCsp = false;
    }
}

转换前的PEM私钥 #

-----BEGIN RSA PRIVATE KEY-----
MIICXQIBAAKBgQC62buBx8rskJOLWBEhzPb8GO06kACOq93S4wp3YADPGAUIQoKt
o80oWMq/k5oQarpuduC3YEbH/mbkKuCNHboUx4D3bhAGhhmh0ahIFXiSVyhWKFe3
Oda/3oVia4zJr4FflDl+ozpMneIltcjf7+jl7JuVeP+aONn7IoZCNSfpZwIDAQAB
AoGAUQkzODL1QCnnw4w7SeSBzY3l/PsNMtM5DkgnduRtFWP+crmdwT8EMBZqQDH8
pFgVaOknxn/70qrz5srtvmYBGFjHdVRqBz01huykyIzxYhKATiljp+Akf72ljpIf
s4zJ5bIQyA9OMYZKoIUjiUlCKBX29baxJ6tNAObOrwgAyGECQQD34XXw6LrAqAKn
i9LJIOMpCbMhqOz5A+yI6xyZnGT9BX1PVOD5BKLezewvFAUacJTxDQ4T13iJ2/pM
u1L+JuXXAkEAwPiE2XzmTsEkOGO6KFfNHqkeh6uwd/WxHcRQgUfhFefl30YtIh1f
j+Zq+b/rmzpkPPIVdl6zUbrWeldsfj2G8QJALyV52j1Zr+UExDtK9yhDLH4EzSUl
FWPSrGQTh4AAkUNnBxy8wYBJPhlqj7W+Fr5NBeAWyl1UNtxZKhkC+wYI9wJBAIqc
OLkMaVYakAzdPaOq5dDnQ+HKJpkUZ2PtVrJ2UiztBQZrHxJJLRJtPVwmSnOW7teE
QHxlK8NCRLtePrUzNtECQQDsq81DzcGXU4VU6zg1m3asW88VCNJ9IR1K3KCWwAFL
IFBSkLkigmyPVJetdA884UOB0MFdex8klEcQCXXbkJOY
-----END RSA PRIVATE KEY-----

问题主要出在以下两点：

• 填充模式不匹配：Java使用的是OAEPWithSHA-256AndMGF1Padding，而原代码中rsa.Decrypt(resultBytes, false)的第二个参数false对应PKCS#1 v1.5填充，两者完全不兼容，这是抛出错误的核心原因。
• API选择过时：RSACryptoServiceProvider是.NET Framework时代的旧API，在.NET Core/.NET 5+中已被标记为过时，推荐使用更通用的RSA抽象类。

修正后的代码 #

// encrypted string result is hello
const string encryptedString = "HhB77zNHCiB/CWa8v5VcaUNdi/M/mE9us8mQ4be1o2f3G/rQpsAcD8aue4QRJsOliekHIqaI9vrkyyLIDTJQDbkb15rweHZwwUr0YFqHFAq/PMt9tBph2U7n9zZN0zVDiFP/J4J8FZBGsLFx432YQP7DEi62fbHYY8fm1lXLx/Q=";
const string privateKey = "<RSAKeyValue><Modulus>utm7gcfK7JCTi1gRIcz2/BjtOpAAjqvd0uMKd2AAzxgFCEKCraPNKFjKv5OaEGq6bnbgt2BGx/5m5CrgjR26FMeA924QBoYZodGoSBV4klcoVihXtznWv96FYmuMya+BX5Q5fqM6TJ3iJbXI3+/o5eyblXj/mjjZ+yKGQjUn6Wc=</Modulus><Exponent>AQAB</Exponent><P>9+F18Oi6wKgCp4vSySDjKQmzIajs+QPsiOscmZxk/QV9T1Tg+QSi3s3sLxQFGnCU8Q0OE9d4idv6TLtS/ibl1w==</P><Q>wPiE2XzmTsEkOGO6KFfNHqkeh6uwd/WxHcRQgUfhFefl30YtIh1fj+Zq+b/rmzpkPPIVdl6zUbrWeldsfj2G8Q==</Q><DP>LyV52j1Zr+UExDtK9yhDLH4EzSUlFWPSrGQTh4AAkUNnBxy8wYBJPhlqj7W+Fr5NBeAWyl1UNtxZKhkC+wYI9w==</DP><DQ>ipw4uQxpVhqQDN09o6rl0OdD4commRRnY+1WsnZSLO0FBmsfEkktEm09XCZKc5bu14RAfGUrw0JEu14+tTM20Q==</DQ><InverseQ>7KvNQ83Bl1OFVOs4NZt2rFvPFQjSfSEdStyglsABSyBQUpC5IoJsj1SXrXQPPOFDgdDBXXsfJJRHEAl125CTmA==</InverseQ><D>UQkzODL1QCnnw4w7SeSBzY3l/PsNMtM5DkgnduRtFWP+crmdwT8EMBZqQDH8pFgVaOknxn/70qrz5srtvmYBGFjHdVRqBz01huykyIzxYhKATiljp+Akf72ljpIfs4zJ5bIQyA9OMYZKoIUjiUlCKBX29baxJ6tNAObOrwgAyGE=</D></RSAKeyValue>";

using (var rsa = RSA.Create())
{
    try
    {
        rsa.FromXmlString(privateKey);
        var encryptedBytes = Convert.FromBase64String(encryptedString);
        // 指定OAEP填充，哈希算法为SHA256，匹配Java的加密配置
        var decryptedBytes = rsa.Decrypt(encryptedBytes, RSAEncryptionPadding.OaepSHA256);
        var decryptedData = Encoding.UTF8.GetString(decryptedBytes);
        Console.WriteLine(decryptedData);
    }
    finally
    {
        rsa.Clear();
    }
}

额外说明 #

• 无需将PEM私钥转为XML，可直接用rsa.ImportFromPem(privateKeyPem)方法导入，避免在线转换可能带来的错误。
• RSA跨语言加密解密的核心要求是：密钥对完全匹配，填充、哈希算法的配置严格一致。

内容的提问来源于stack exchange，提问作者JoelFerreira