Signing X509 Certs w/BouncyCastle - invalid digita

Question

Possible Duplicate:
Generated signed X.509 client certificate is invalid (no certificate chain to its CA)

I followed the example at:

http://www.bouncycastle.org/wiki/display/JA1/X.509+Public+Key+Certificate+and+Certification+Request+Generation

But the resulting signed client certificate has the following error when opened in windows:

"This file is invalid for use as the following: Security Certificate"

If I install it anyway and view it with certmgr, the certification path looks OK - I see my self-signed Certificate Authority (which is fine, no problems there) but the client cert has the following status:

"This certificate has an invalid digital signature."

If I call X509Certificate.Verify() it throws the following exception:

"Public key presented not for certificate signature"

Yet I'm using the same exact public key extracted from the Pkcs10CertificationRequest and when I called Verify() on that it's fine.

Any ideas? After days of struggling through this, I've got all the pieces working except this last one - and what's really confusing is that my self-signed CA cert is fine. There's just something going on with the client cert. Here's the entire block of code:

        TextReader textReader = new StreamReader("certificaterequest.pkcs10");
        PemReader pemReader = new PemReader(textReader);

        Pkcs10CertificationRequest certificationRequest = (Pkcs10CertificationRequest)pemReader.ReadObject();
        CertificationRequestInfo certificationRequestInfo = certificationRequest.GetCertificationRequestInfo();
        SubjectPublicKeyInfo publicKeyInfo = certificationRequestInfo.SubjectPublicKeyInfo;

        RsaPublicKeyStructure publicKeyStructure = RsaPublicKeyStructure.GetInstance(publicKeyInfo.GetPublicKey());

        RsaKeyParameters publicKey = new RsaKeyParameters(false, publicKeyStructure.Modulus, publicKeyStructure.PublicExponent);

        bool certIsOK = certificationRequest.Verify(publicKey);
        // public key is OK here...

        // get the server certificate
        Org.BouncyCastle.X509.X509Certificate serverCertificate = DotNetUtilities.FromX509Certificate(System.Security.Cryptography.X509Certificates.X509Certificate.CreateFromCertFile("servermastercertificate.cer"));

        // get the server private key
        byte[] privateKeyBytes = File.ReadAllBytes("serverprivate.key");
        AsymmetricKeyParameter serverPrivateKey = PrivateKeyFactory.CreateKey(privateKeyBytes);

        // generate the client certificate
        X509V3CertificateGenerator generator = new X509V3CertificateGenerator();

        generator.SetSerialNumber(BigInteger.ProbablePrime(120, new Random()));
        generator.SetIssuerDN(serverCertificate.SubjectDN);
        generator.SetNotBefore(DateTime.Now);
        generator.SetNotAfter(DateTime.Now.AddYears(5));
        generator.SetSubjectDN(certificationRequestInfo.Subject);
        generator.SetPublicKey(publicKey);
        generator.SetSignatureAlgorithm("SHA512withRSA");
        generator.AddExtension(X509Extensions.AuthorityKeyIdentifier, false, new AuthorityKeyIdentifierStructure(serverCertificate));
        generator.AddExtension(X509Extensions.SubjectKeyIdentifier, false, new SubjectKeyIdentifierStructure(publicKey));

        var newClientCert = generator.Generate(serverPrivateKey);

        newClientCert.Verify(publicKey); // <-- this blows up

        return DotNetUtilities.ToX509Certificate(newClientCert).Export(X509ContentType.Pkcs12, "user password");

Answer 1

I figured this out. If you call X509Certificate.Verify(publicKey) you have to pass the CA's public key, not the client's public key from the Pkcs10CertificationRequest.