Problem in creating X509Certificate2 Public Key

Question

I have an existing asp.net application where I use X509Certificate2 private and public keys. I am migrating it to netcoreapp2.1 (MVC). I'm facing a problem in creating a public key with X509Certificate2. I have the below code

  public string CertificatePublicKeyEncrypt(string stringToEncrypt, string certficatePath)
    {
        byte[] bytesToEncrypt = ASCIIEncoding.ASCII.GetBytes(stringToEncrypt);

        RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();

        X509Certificate2 cert = new X509Certificate2(certficatePath);

        RSACryptoServiceProvider rsa = cert.PublicKey.Key as RSACryptoServiceProvider;

        byte[] encryptedData = rsa.Encrypt(bytesToEncrypt, false);

        return Convert.ToBase64String(encryptedData);
    }

in asp.net application, cert.Handle value is "0x0792e4a0" and rsa is created successfully where the certificate location is determined using Server.MapPath function as shown:

   req.Sender = helper.CreateSenderObj(txt_sender_id.Text, txt_sender_name.Text, txt_efinance_password.Text, Server.MapPath("~/Certificates/InternetPaymentCrt.cer"));

Handle Value in asp.net Project but in our MVC project cert.Handle value is"0x0000019d814fffa0" and then rsa is null where the certificate location is determined using Hosting.ContentRootPath function as shown:

 var path = $"{Hosting.ContentRootPath}\\Certificates\\InternetPaymentCrt.cer"; 
         req.Sender = helper.CreateSenderObj(VM.SenderId, VM.SenderName, VM.SenderPassword,path);   

Handle Value in MCV Project and gives null exception error as follows System.NullReferenceException

Answer 1

In .NET Core applications, X509Certificate2.PublicKey and X509Certificate2.PrivateKey are literally obsolete. You have to use X509Certificate2 extension methods (corresponding method depending on key algorithm) to retrieve public and private keys.