How do you parse the Subject Alternate Names from an X509Certificate2?

Question

Is there an easy way to get the Subject Alternate Names from an X509Certificate2 object?

        foreach (X509Extension ext in certificate.Extensions)
               


        

Answer 1

Based on the answer from Minh, here is a self-contained static function that should return them all

    public static IEnumerable ParseSujectAlternativeNames(X509Certificate2 cert)
    {
        Regex sanRex = new Regex(@"^DNS Name=(.*)", RegexOptions.Compiled | RegexOptions.CultureInvariant);

        var sanList = from X509Extension ext in cert.Extensions
                      where ext.Oid.FriendlyName.Equals("Subject Alternative Name", StringComparison.Ordinal)
                      let data = new AsnEncodedData(ext.Oid, ext.RawData)
                      let text = data.Format(true)
                      from line in text.Split(new char[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries)
                      let match = sanRex.Match(line)
                      where match.Success && match.Groups.Count > 0 && !string.IsNullOrEmpty(match.Groups[1].Value)
                      select match.Groups[1].Value;

        return sanList;
    }