X509Certificate2.Extensions Property

 

Gets a collection of X509Extension objects.

Namespace:   System.Security.Cryptography.X509Certificates
Assembly:  System (in System.dll)

public X509ExtensionCollection Extensions { get; }

Exception Condition
CryptographicException

The certificate is unreadable.

The extensions defined in the X.509 v3 certificate format allow additional data to be included in the certificate. A number of extensions are defined by ISO in the X.509 v3 definition as well as by PKIX in RFC 3280, "Certificate and Certificate Revocation List (CRL) Profile." Common extensions include information regarding key usage (X509KeyUsageExtension), key identifiers (X509SubjectKeyIdentifierExtension), certificate policies, revocation information (CRL Distribution Point extension), and other uses.

The following code example opens the current user certificate store, selects only active certificates, then allows the user to select one or more certificates. The example then writes certificate information to the console.

using System;
using System.Security.Cryptography;
using System.Security.Permissions;
using System.IO;
using System.Security.Cryptography.X509Certificates;

class CertSelect
{
    static void Main()
    {
        X509Store store = new X509Store("MY",StoreLocation.CurrentUser);
        store.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly);

        X509Certificate2Collection collection = (X509Certificate2Collection)store.Certificates;
        X509Certificate2Collection fcollection = (X509Certificate2Collection)collection.Find(X509FindType.FindByTimeValid,DateTime.Now,false);
        X509Certificate2Collection scollection = X509Certificate2UI.SelectFromCollection(fcollection, "Test Certificate Select","Select a certificate from the following list to get information on that certificate",X509SelectionFlag.MultiSelection);
        Console.WriteLine("Number of certificates: {0}{1}",scollection.Count,Environment.NewLine);

        foreach (X509Certificate2 x509 in scollection)
        {
            try
            {
                byte[] rawdata = x509.RawData;
                Console.WriteLine("Content Type: {0}{1}",X509Certificate2.GetCertContentType(rawdata),Environment.NewLine);
                Console.WriteLine("Friendly Name: {0}{1}",x509.FriendlyName,Environment.NewLine);
                Console.WriteLine("Certificate Verified?: {0}{1}",x509.Verify(),Environment.NewLine);
                Console.WriteLine("Simple Name: {0}{1}",x509.GetNameInfo(X509NameType.SimpleName,true),Environment.NewLine);
                Console.WriteLine("Signature Algorithm: {0}{1}",x509.SignatureAlgorithm.FriendlyName,Environment.NewLine);
                Console.WriteLine("Private Key: {0}{1}",x509.PrivateKey.ToXmlString(false),Environment.NewLine);
                Console.WriteLine("Public Key: {0}{1}",x509.PublicKey.Key.ToXmlString(false),Environment.NewLine);
                Console.WriteLine("Certificate Archived?: {0}{1}",x509.Archived,Environment.NewLine);
                Console.WriteLine("Length of Raw Data: {0}{1}",x509.RawData.Length,Environment.NewLine);
                X509Certificate2UI.DisplayCertificate(x509);
                x509.Reset();
            }
            catch (CryptographicException)
            {
                Console.WriteLine("Information could not be written out for this certificate.");
            }
        }
        store.Close();
    }
}

.NET Framework
Available since 2.0
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