X509Certificate2.PublicKey Property

Definition

Namespace:

System.Security.Cryptography.X509Certificates

Assemblies:

netstandard.dll, System.Security.Cryptography.dll

Source:

X509Certificate2.cs

Gets a PublicKey object associated with a certificate.

C#

public System.Security.Cryptography.X509Certificates.PublicKey PublicKey { get; }

Property Value

PublicKey

A PublicKey object.

Exceptions

CryptographicException

The key value is not an RSA or DSA key, or the key is unreadable.

Examples

The following code example creates a command-line executable that takes a certificate file as an argument and prints various certificate properties to the console.

C#

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("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();
    }
}

Remarks

This property returns a PublicKey object, which contains the object identifier (Oid) representing the public key algorithm, the ASN.1-encoded parameters, and the ASN.1-encoded key value.

You can also obtain the key as an AsymmetricAlgorithm object by referencing the PublicKey property. This property supports only RSA or DSA keys, so it returns either an RSACryptoServiceProvider or a DSACryptoServiceProvider object that represents the public key.

Applies to