public static Func<X509Certificate2, string> FromIssuerRegistry(IssuerNameRegistry registry)
{
return cert =>
{
var chain = new X509Chain
{
ChainPolicy =
{
RevocationMode = X509RevocationMode.NoCheck
}
};
chain.Build(cert);
var elems = chain.ChainElements;
return registry.GetIssuerName(
new X509SecurityToken(
elems.Count == 1 ? elems[0].Certificate : elems[1].Certificate));
};
}
internal static string GetCertificateIssuerName(X509Certificate2 certificate, IssuerNameRegistry issuerNameRegistry)
{
if (certificate == null)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("certificate");
}
if (issuerNameRegistry == null)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("issuerNameRegistry");
}
X509Chain chain = new X509Chain();
chain.ChainPolicy.RevocationMode = X509RevocationMode.NoCheck;
chain.Build(certificate);
X509ChainElementCollection elements = chain.ChainElements;
string issuer = null;
if (elements.Count > 1)
{
using (X509SecurityToken token = new X509SecurityToken(elements[1].Certificate))
{
issuer = issuerNameRegistry.GetIssuerName(token);
}
}
else
{
// This is a self-issued certificate. Use the thumbprint of the current certificate.
using (X509SecurityToken token = new X509SecurityToken(certificate))
{
issuer = issuerNameRegistry.GetIssuerName(token);
}
}
for (int i = 1; i < elements.Count; ++i)
{
// Resets the state of the certificate and frees resources associated with it.
elements[i].Certificate.Reset();
}
return issuer;
}