Get Private Key from BouncyCastle X509 Certificate? C#

问题

Normally when I grab an X509Certificate2 out of my keystore I can call .PrivateKey to retrieve the cert's private key as an AsymmetricAlgorithm. However I have decided to use Bouncy Castle and its instance of X509Certificate only has a getPublicKey(); I cannot see a way to get the private key out of the cert. Any ideas?

I get the an X509Certificate2 from my Windows-MY keystore then use:

//mycert is an X509Certificate2 retrieved from Windows-MY Keystore
X509CertificateParser certParser = new X509CertificateParser();
X509Certificate privateCertBouncy = certParser.ReadCertificate(mycert.GetRawCertData());
AsymmetricKeyParameter pubKey = privateCertBouncy.GetPublicKey();
//how do i now get the private key to make a keypair?

Is there anyway to convert a AsymmetricAlgorithm(C# private key) to a AsymmetricKeyParameter(bouncycastle private key)?

回答1:

Don't know BouncyCastle that much but it seems to me that the simple thing to do is to recreate the key based on the key parameters.


    public static AsymmetricKeyParameter TransformRSAPrivateKey(AsymmetricAlgorithm privateKey)
    {
        RSACryptoServiceProvider prov = privateKey as RSACryptoServiceProvider;
        RSAParameters parameters = prov.ExportParameters(true);

        return new RsaPrivateCrtKeyParameters(
            new BigInteger(1,parameters.Modulus),
            new BigInteger(1,parameters.Exponent),
            new BigInteger(1,parameters.D),
            new BigInteger(1,parameters.P),
            new BigInteger(1,parameters.Q),
            new BigInteger(1,parameters.DP),
            new BigInteger(1,parameters.DQ),
            new BigInteger(1,parameters.InverseQ));
    }

You can call the code by using


AsymmetricKeyParameter bouncyCastlePrivateKey = TransformRSAPrivateKey(mycert.PrivateKey);

Obviously this assumes that the certificate includes a RSA Key but the same result can be achieved for DSA with DSACryptoServiceProvider and DSAParameters

回答2:

Akp = Org.BouncyCastle.Security.DotNetUtilities.GetKeyPair(this.Certificate.PrivateKey).Private;

回答3:

Find .NET X509Certificate2:

X509Certificate2 cert = this.FindCertificate(certificateFriendlyName);

Parse it to BouncyCastle certificate and use X509Certificate2Signature to get signature:

var parser = new X509CertificateParser();
var bouncyCertificate = parser.ReadCertificate(cert.RawData);
var algorithm = DigestAlgorithms.GetDigest(bouncyCertificate.SigAlgOid);
var signature = new X509Certificate2Signature(cert, algorithm);

来源：https://stackoverflow.com/questions/3240222/get-private-key-from-bouncycastle-x509-certificate-c-sharp

标签

x509certificate

bouncycastle

private-key