I have a .cer file, .key and a password. I need to convert them to a .pfx file in .NET 6 but I have not a clear idea how to do it.

With the help of ChatGPT I came up with this code but it is not working as it should, I get an exception:

System.Security.Cryptography.CryptographicException: ASN1 corrupted data.
   ---> System.Formats.Asn1.AsnContentException: The provided data is tagged with 'Universal' class value '16', but it should have been 'Universal' class value '2'.

My code:

public async Task<string> ConvertToPfx(string certFilePath, string keyFilePath, string password)
{
    byte[] certData = await File.ReadAllBytesAsync(certFilePath);
    var certificate = new X509Certificate2(certData);

    byte[] keyData = await File.ReadAllBytesAsync(keyFilePath);
    RSA rsa = RSA.Create();
    rsa.ImportRSAPrivateKey(keyData, out _);  //  <-- Exception here

    var certWithPrivateKey = certificate.CopyWithPrivateKey(rsa);

    byte[] pfxData = certWithPrivateKey.Export(X509ContentType.Pfx, password);
    string pfxPath = Path.Combine(Path.GetTempPath(), $"{Path.GetFileNameWithoutExtension(certFilePath)}.pfx");
    await File.WriteAllBytesAsync(pfxPath, pfxData);

    return pfxPath;
}

Feel free to make the necessary changes or propose other alternatives.