how to find a known client certificate's root certificate in rootStore?

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string issuertofcert = cert.GetIssuerName();
Certificate root = castore.FindCertificateBySubjectString(issuertofcert);
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the above does not work because there can be two root certificates having the same subject string. I want to get the
right root certificate.

actually, verifyChain(cert) method must find the root certificate somewhere inside the code. how can i get it?

Also, can i get the x500 string of my root certificate's subject from my client certificate and use it in FindCertificateBySubjectName(rootcert)? (by the way, is there a possibility that two root certificates having the same subject name? if so, this way does not work either.)

or;

is there any other way?

I would appreciate it so much if anyone replies fast.
Thanks in advance

You can use the following code to get the root certificate [if it can be found]:

CertificateChain cc = new CertificateChain(mycert);
Certificate[] certs = cc.GetCertificates();

The last certificate in the array (certs[certs.Length-1]) is the root certificate -- if it can be found.

I tried it but it did not work. The thing is I can verify the certificate which means the root should be found when cc.GetCertificates() in your suggestion code. But the array's length is always 1 and the only certificate in it is my client certificate.

"verify" in my previous post means "chain verify". cc.VerifyChain(...)
gives me CertificateStatus.ValidCertificate. It can find the root in my CertificateStore.RootStore. But cc.GetCertificates() can not. why?

Have you tried sepcifying the ROOT store as the additional store when creating instantiating the CertificateChain instance?

root = new CertificateStore(CertificateStore.RootStore);
cc = new CertificateChain(mycert, root);

does not work. same result. array with 1 cert in it. i coded the certificate parser myself. many thanks anyway. just keep developing the libraries. (suggestion: i could not find a free asn1 parser for c#)