X509Certificate 中的公钥和私钥

Question

I am using the C# System.Security.Cryptography library to create a certificate for apache. I already have a CA certificate which I try to use for signing the server certificate.

I am using the CertificateRequest.Create method to create the certificate. Unfortunately it doesn't provide a private key which I need for apache (.pem/.crt and.key). How do I save the certificate and get both needed files for apache?

OpenSSL is not a solution for me.

X509Certificate2 signedCert = request.Create(issuerCert, DateTimeOffset.Now, 
    DateTimeOffset.Now.AddYears(5), new byte[] { 1, 2, 3, 4 });

I can save the public key of the signed cert by doing this:

File.WriteAllText(path + "cert.pem",
            "-----BEGIN CERTIFICATE-----\r\n"
            + Convert.ToBase64String(signedCert.Export(X509ContentType.Cert), Base64FormattingOptions.InsertLineBreaks)
            + "\r\n-----END CERTIFICATE-----");

How do I get the private key and save it as.key file?

Answer 1

With .NET Core 3.0:

File.WriteAllText(path + "cert.pem",
    "-----BEGIN PRIVATE KEY-----\r\n"
        + Convert.ToBase64String(
            key.ExportPkcs8PrivateKey(),
            Base64FormattingOptions.InsertLineBreaks)
        + "\r\n-----END PRIVATE KEY-----");

Where key is any AsymmetricAlgorithm type (which you need to just... have somewhere -- probably passed into the CertificateRequest constructor, but since you created a chain-signed certificate the CertificateRequest would have worked from a public-key-only instance).