Overview

Provides static extension methods for the X509Certificate2 class to simplify the retrieval and manipulation of certificate extensions.

This class is part of the System.Security.Cryptography.X509Certificates namespace.

Members

Methods

GetEkuOids()

Retrieves the Object Identifiers (OIDs) for all Enhanced Key Usage (EKU) extensions present in the certificate.

public static OidCollection GetEkuOids(
    this X509Certificate2 certificate
);

Parameters

  • certificate: The X509Certificate2 object to inspect.

Return Value

An OidCollection containing the OIDs of the EKUs found in the certificate.

Example

using System;
using System.Security.Cryptography.X509Certificates;
using System.Net.Security; // Required for extension methods

public class Example
{
    public static void Main(string[] args)
    {
        // Load a certificate (replace with your actual certificate loading logic)
        X509Certificate2 cert = new X509Certificate2("path/to/your/certificate.cer");

        OidCollection ekuOids = cert.GetEkuOids();

        Console.WriteLine($"Enhanced Key Usages for certificate: {cert.Subject}");
        if (ekuOids.Count > 0)
        {
            foreach (Oid oid in ekuOids)
            {
                Console.WriteLine($"- OID: {oid.Value}, Name: {oid.FriendlyName}");
            }
        }
        else
        {
            Console.WriteLine("  No Enhanced Key Usages found.");
        }
    }
}

GetSubjectAlternativeNames()

Retrieves the Subject Alternative Name (SAN) entries from the certificate. This includes DNS names, IP addresses, etc.

public static IList<string> GetSubjectAlternativeNames(
    this X509Certificate2 certificate
);

Parameters

  • certificate: The X509Certificate2 object to inspect.

Return Value

A IList<string> containing the SAN entries. Each entry is typically a DNS name or IP address.

Example

using System;
using System.Collections.Generic;
using System.Security.Cryptography.X509Certificates;
using System.Net.Security; // Required for extension methods

public class Example
{
    public static void Main(string[] args)
    {
        X509Certificate2 cert = new X509Certificate2("path/to/your/certificate.cer");

        IList<string> sanEntries = cert.GetSubjectAlternativeNames();

        Console.WriteLine($"Subject Alternative Names for certificate: {cert.Subject}");
        if (sanEntries.Count > 0)
        {
            foreach (string san in sanEntries)
            {
                Console.WriteLine($"- {san}");
            }
        }
        else
        {
            Console.WriteLine("  No Subject Alternative Names found.");
        }
    }
}

GetRawExtensionValue(string oid)

Retrieves the raw byte array value of a certificate extension specified by its Object Identifier (OID).

public static byte[] GetRawExtensionValue(
    this X509Certificate2 certificate,
    string oid
);

Parameters

  • certificate: The X509Certificate2 object to inspect.
  • oid: The OID of the extension to retrieve.

Return Value

A byte array representing the raw value of the extension, or null if the extension is not found.

HasExtension(string oid)

Checks if a certificate contains a specific extension, identified by its OID.

public static bool HasExtension(
    this X509Certificate2 certificate,
    string oid
);

Parameters

  • certificate: The X509Certificate2 object to inspect.
  • oid: The OID of the extension to check for.

Return Value

true if the certificate contains the specified extension; otherwise, false.