I wrote a identification web page a while back that looked for a client certificate and if found would display the certificate information. I believe that is what you are looking for... Here is the page:
<%@ Page Language="C#" Trace="false" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<%@ Import Namespace="System.Security.Cryptography.X509Certificates" %>
<%@ Import Namespace="System.Security.Cryptography" %>
<script runat="server">
//protected void Page_Load(object sender, EventArgs e)
//{ }
void LoadCertInfo()
{
string para = "<div style='margin: 10px 0 0 0; font-weight: bold'>{0}</div>";
string subpara = "<div style='margin-left: 15px; font-size: 90%'>{0}</div>";
if (Page.Request.ClientCertificate.IsPresent)
{
Response.Write("<hr /><div style='width: 500px; margin: 20px auto'>");
Response.Write("<h3 style='width: 500px; margin: 20px auto'>Client Certificate Information</h3>");
try
{
X509Certificate2 x509Cert2 = new X509Certificate2(Page.Request.ClientCertificate.Certificate);
Response.Write(string.Format(para, "Issued To:"));
Response.Write(string.Format(subpara, x509Cert2.Subject));
Response.Write(string.Format(para, "Issued By:"));
Response.Write(string.Format(subpara, x509Cert2.Issuer));
Response.Write(string.Format(para, "Friendly Name:"));
Response.Write(string.Format(subpara, string.IsNullOrEmpty(x509Cert2.FriendlyName) ? "(None Specified)" : x509Cert2.FriendlyName));
Response.Write(string.Format(para, "Valid Dates:"));
Response.Write(string.Format(subpara, "From: " + x509Cert2.GetEffectiveDateString()));
Response.Write(string.Format(subpara, "To: " + x509Cert2.GetExpirationDateString()));
Response.Write(string.Format(para, "Thumbprint:"));
Response.Write(string.Format(subpara, x509Cert2.Thumbprint));
//Response.Write(string.Format(para, "Public Key:"));
//Response.Write(string.Format(subpara, x509Cert2.GetPublicKeyString()));
#region EKU Section - Retrieve EKU info and write out each OID
X509EnhancedKeyUsageExtension ekuExtension = (X509EnhancedKeyUsageExtension)x509Cert2.Extensions["Enhanced Key Usage"];
if (ekuExtension != null)
{
Response.Write(string.Format(para, "Enhanced Key Usages (" + ekuExtension.EnhancedKeyUsages.Count.ToString() + " found)"));
OidCollection ekuOids = ekuExtension.EnhancedKeyUsages;
foreach (Oid ekuOid in ekuOids)
Response.Write(string.Format(subpara, ekuOid.FriendlyName + " (OID: " + ekuOid.Value + ")"));
}
else
{
Response.Write(string.Format(para, "No EKU Section Data"));
}
#endregion // EKU Section
#region Subject Alternative Name Section
X509Extension sanExtension = (X509Extension)x509Cert2.Extensions["Subject Alternative Name"];
if (sanExtension != null)
{
Response.Write(string.Format(para, "Subject Alternative Name:"));
Response.Write(string.Format(subpara, sanExtension.Format(true)));
}
else
{
Response.Write(string.Format(para, "No Subject Alternative Name Data"));
}
#endregion // Subject Alternative Name Section
#region Certificate Policies Section
X509Extension policyExtension = (X509Extension)x509Cert2.Extensions["Certificate Policies"];
if (policyExtension != null)
{
Response.Write(string.Format(para, "Certificate Policies:"));
Response.Write(string.Format(subpara, policyExtension.Format(true)));
}
else
{
Response.Write(string.Format(para, "No Certificate Policies Data"));
}
#endregion //Certificate Policies Section
// Example on how to enumerate all extensions
//foreach (X509Extension extension in x509Cert2.Extensions)
// Response.Write(string.Format(para, extension.Oid.FriendlyName + "(" + extension.Oid.Value + ")"));
}
catch (Exception ex)
{
Response.Write(string.Format(para, "An error occured:"));
Response.Write(string.Format(subpara, ex.Message));
Response.Write(string.Format(subpara, ex.StackTrace));
}
finally
{
Response.Write("</div>");
}
}
}
</script>
<html>
<head runat="server">
<title><% Page.Response.Write(System.Environment.MachineName); %></title>
</head>
<body>
<% LoadCertInfo(); %>
</body>
</html>