how to create a completely new x509Certificate2 in .net?

user_276586 0
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I google it from web, find many samples to generate a new x509Certificate2 from a file in .net, but there is no one sample to show how to generate a completely new x509Certificate2 from the beginning in .net.

Is there any one that can tell me how to do it in .net?

Thank you very much.

x509certificate2 .net
6 Answers

Checkout CertificateRequest (Name Space: System.Security.Cryptography.X509Certificates)...

 public static X509Certificate2 GenerateSelfSignedCertificate()
    {
        string secp256r1Oid = "1.2.840.10045.3.1.7";  //oid for prime256v1(7)  other identifier: secp256r1
        
        string subjectName = "Self-Signed-Cert-Example";

        var ecdsa = ECDsa.Create(ECCurve.CreateFromValue(secp256r1Oid));

        var certRequest = new CertificateRequest($"CN={subjectName}", ecdsa, HashAlgorithmName.SHA256);

        //add extensions to the request (just as an example)
        //add keyUsage
        certRequest.CertificateExtensions.Add(new X509KeyUsageExtension(X509KeyUsageFlags.DigitalSignature, true));

        X509Certificate2 generatedCert = certRequest.CreateSelfSigned(DateTimeOffset.Now.AddDays(-1), DateTimeOffset.Now.AddYears(10)); // generate the cert and sign!

        X509Certificate2 pfxGeneratedCert = new X509Certificate2(generatedCert.Export(X509ContentType.Pfx)); //has to be turned into pfx or Windows at least throws a security credentials not found during sslStream.connectAsClient or HttpClient request...

     return pfxGeneratedCert;
}
user_115968110

Open ssl for creating x509 certificate

1.Download the Win64 Openssl from the below link.(Win64 OpenSSL v1.1.0j - 37mb installer) URL - https://slproweb.com/products/Win32OpenSSL.html

2.After installation set the system path environment variable.(path = C:\OpenSSL-Win64\bin)

3.Open command prompt and change the directory to desktop.

4.Command for key creation : Private Key : openssl req -x509 -days 365 -newkey rsa:2048 -keyout cert-key.pem -out cert.pem Enter the command and follow the instruction.

5.Now we have 2 files named cert-key.pem and cert.pem in desktop. To create the .pfx file run the below command openssl pkcs12 -export -in cert.pem -inkey cert-key.pem -out x509-cert.pfx and follow the instruction(enter the same password).

6.Command for public key creation : openssl pkcs12 -in x509-cert.pfx -clcerts -nokeys -out x509-cert-public.pem and follow the instruction.

7.Register the certificate to mmc.

user_35320370 
public X509Certificate2 GetCertificate()
{
    var config = InitConfiguration();
    var certificateSubject = "X509Subject";
    var certificateStoreName = "X509StoreName";
    var certificateStoreLocation = "X509StoreLocation";
    var thumbPrint = "ThumbPrint";

    var storeName = (StoreName)Enum.Parse(typeof(StoreName), certificateStoreName, true);
    var storeLocation = (StoreLocation)Enum.Parse(typeof(StoreLocation), certificateStoreLocation, true);

    var certificateStore = new X509Store(storeName, storeLocation);
    certificateStore.Open(OpenFlags.ReadOnly);

    foreach (var storeCertificate in certificateStore.Certificates)
    {
        if (storeCertificate.Thumbprint.ToLower(System.Globalization.CultureInfo.CurrentCulture) == thumbPrint.ToLower(System.Globalization.CultureInfo.CurrentCulture))
        {return storeCertificate;
        }
    }
certificateStore.Close();
    return null;
}
user_35320370
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