.NET API

X509Certificate2 Class

Represents an X.509 certificate.

Namespace: System.Net.Security

Assembly: System.Security.Cryptography.X509Certificates.dll

Syntax

public sealed class X509Certificate2 : X509Certificate, System.Runtime.Serialization.ISerializable

Methods

Constructors

public X509Certificate2(byte[] rawData)

Initializes a new instance of the X509Certificate2 class by using the specified array of bytes.

public X509Certificate2(string fileName)

Initializes a new instance of the X509Certificate2 class by using the specified file name.

public X509Certificate2(string fileName, string password)

Initializes a new instance of the X509Certificate2 class by using the specified file name and password.

Properties

public string Arch { get; }

Gets the processor architecture associated with the certificate.

public string DnsNameString { get; }

Gets the DNS name associated with the certificate.

public bool HasPrivateKey { get; }

Gets a value that indicates whether the certificate has a private key.

public string Issuer { get; }

Gets the issuer of the X.509 v.3 certificate.

public DateTime NotAfter { get; }

Gets the date and time when the certificate expires.

public DateTime NotBefore { get; }

Gets the date and time when the certificate becomes valid.

public AsymmetricAlgorithm PrivateKey { get; }

Gets the private key associated with the certificate.

public string Subject { get; }

Gets the subject of the X.509 v.3 certificate.

public string Thumbprint { get; }

Gets the thumbprint of the X.509 certificate.

Methods

public bool Verify()

Verifies the X.509 certificate.

public bool Verify(X509Chain chain)

Verifies the X.509 certificate by using the specified certificate chain.

Remarks

The X509Certificate2 class represents an X.509 certificate, which is a digital certificate that uses the public key cryptography standards to bind together a public key with an identity. This identity can be a person, a computer, an organization, or any other entity.

X509Certificate2 objects are commonly used to authenticate the identity of an application, a server, or a client, especially in secure communication protocols like SSL/TLS.

Examples

using System;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;

public class CertificateExample
{
    public static void Main(string[] args)
    {
        try
        {
            // Load a certificate from a file
            string certificatePath = "mycertificate.pfx";
            string certificatePassword = "mypassword";
            X509Certificate2 certificate = new X509Certificate2(certificatePath, certificatePassword);

            Console.WriteLine($"Subject: {certificate.Subject}");
            Console.WriteLine($"Issuer: {certificate.Issuer}");
            Console.WriteLine($"Thumbprint: {certificate.Thumbprint}");
            Console.WriteLine($"Valid from: {certificate.NotBefore}");
            Console.WriteLine($"Expires on: {certificate.NotAfter}");
            Console.WriteLine($"Has Private Key: {certificate.HasPrivateKey}");

            // You can also use it in an SslStream
            // Example: NegotiateClientAuthentication(stream, certificate);
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred: {ex.Message}");
        }
    }

    // Placeholder for an example using SslStream
    // public static void NegotiateClientAuthentication(System.IO.Stream stream, X509Certificate2 clientCertificate)
    // {
    //     SslStream sslStream = new SslStream(stream, false,
    //         new RemoteCertificateValidationCallback(ValidateServerCertificate),
    //         new LocalCertificateSelectionCallback(SelectClientCertificate));
    //
    //     // ... further SSL/TLS handshake logic ...
    // }
    //
    // public static bool ValidateServerCertificate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
    // {
    //     // Implement your server certificate validation logic here
    //     return true;
    // }
    //
    // public static X509Certificate SelectClientCertificate(object sender, string targetHost, X509CertificateCollection localCertificates, X509Certificate remoteCertificate, string acceptableIssuers)
    // {
    //     // Select the appropriate client certificate from the collection
    //     return localCertificates[0];
    // }
}

Exceptions