Convert different certificate revocation list formats in .net

Question

I need to convert a bunch of certificate revocation list in .crl extension,they are in DER format (Binary), and I need to convert them into PEM format (Base64 string representation of the binary content of each .crl file).

As per instructions in Convert .der to .pem using OpenSSL-Net, I have created the following code trying to convert a single .crl file from its DER format to PEM format:

    private static void generateCrl()
    {
        byte [] certbyte = File.ReadAllBytes("D:\\certsunzip\\DODIDCA_44.crl");
        Console.WriteLine("First byte: {0}", certbyte[0]);
        X509Certificate2 cert = new X509Certificate2(certbyte);
        string pem = "-----BEGIN X509 CRL-----\r\n" + Convert.ToBase64String(cert.RawData, Base64FormattingOptions.InsertLineBreaks) + "-----END X509 CRL-----";
        using (StreamWriter outputFile = new StreamWriter(@"D:\certsunzip\test.crl"))
        {
            foreach (char chr in pem)
            outputFile.WriteLine(chr);
        }
    }

However, when I run the code, the X509Certificate2 constructor is throwing me an CryptographicException saying "Cannot find the requested object". I would like to know is there another way I can do this conversion, maybe the X509Certificate2 constructor does not like the crl files?

Answer 1

Remove 3rd line, because it doesn't make sense (because X509Certificate2 class doesn't support CRLs) and use 'certbyte' variable on a 4th line:

private static void generateCrl()
{
    byte [] certbyte = File.ReadAllBytes("D:\\certsunzip\\DODIDCA_44.crl");
    Console.WriteLine("First byte: {0}", certbyte[0]);
    string pem = "-----BEGIN X509 CRL-----\r\n" + Convert.ToBase64String(certbyte, Base64FormattingOptions.InsertLineBreaks) + "-----END X509 CRL-----";
    using (StreamWriter outputFile = new StreamWriter(@"D:\certsunzip\test.crl"))
    {
        outputFile.Write(pem);
    }
}

This will work.