X509Extension Classe

Definição

public ref class X509Extension : System::Security::Cryptography::AsnEncodedData

public class X509Extension : System.Security.Cryptography.AsnEncodedData

type X509Extension = class
    inherit AsnEncodedData

Public Class X509Extension
Inherits AsnEncodedData

Herança

Object

AsnEncodedData

X509Extension

Derivado

System.Security.Cryptography.X509Certificates.X509AuthorityInformationAccessExtension

System.Security.Cryptography.X509Certificates.X509AuthorityKeyIdentifierExtension

System.Security.Cryptography.X509Certificates.X509BasicConstraintsExtension

System.Security.Cryptography.X509Certificates.X509EnhancedKeyUsageExtension

System.Security.Cryptography.X509Certificates.X509KeyUsageExtension

Mais…

Exemplos

O exemplo de código seguinte demonstra o uso da X509Extension classe.

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

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

            X509Certificate2Collection collection = (X509Certificate2Collection)store.Certificates;
            for (int i = 0; i < collection.Count; i++)
            {
                foreach (X509Extension extension in collection[i].Extensions)
                {
                    Console.WriteLine(extension.Oid.FriendlyName + "(" + extension.Oid.Value + ")");

                    if (extension.Oid.FriendlyName == "Key Usage")
                    {
                        X509KeyUsageExtension ext = (X509KeyUsageExtension)extension;
                        Console.WriteLine(ext.KeyUsages);
                    }

                    if (extension.Oid.FriendlyName == "Basic Constraints")
                    {
                        X509BasicConstraintsExtension ext = (X509BasicConstraintsExtension)extension;
                        Console.WriteLine(ext.CertificateAuthority);
                        Console.WriteLine(ext.HasPathLengthConstraint);
                        Console.WriteLine(ext.PathLengthConstraint);
                    }

                    if (extension.Oid.FriendlyName == "Subject Key Identifier")
                    {
                        X509SubjectKeyIdentifierExtension ext = (X509SubjectKeyIdentifierExtension)extension;
                        Console.WriteLine(ext.SubjectKeyIdentifier);
                    }

                    if (extension.Oid.FriendlyName == "Enhanced Key Usage")
                    {
                        X509EnhancedKeyUsageExtension ext = (X509EnhancedKeyUsageExtension)extension;
                        OidCollection oids = ext.EnhancedKeyUsages;
                        foreach (Oid oid in oids)
                        {
                            Console.WriteLine(oid.FriendlyName + "(" + oid.Value + ")");
                        }
                    }
                }
            }
            store.Close();
        }
        catch (CryptographicException)
        {
            Console.WriteLine("Information could not be written out for this certificate.");
        }
    }
}

Imports System.Security.Cryptography
Imports System.Security.Cryptography.X509Certificates



Module CertSelect

    Sub Main()
        Try
            Dim store As New X509Store("MY", StoreLocation.CurrentUser)
            store.Open(OpenFlags.ReadOnly Or OpenFlags.OpenExistingOnly)

            Dim collection As X509Certificate2Collection = CType(store.Certificates, X509Certificate2Collection)
            For i As Integer = 0 To collection.Count - 1
                Dim extension As X509Extension
                For Each extension In collection(i).Extensions
                    Console.WriteLine(extension.Oid.FriendlyName + "(" + extension.Oid.Value + ")")


                    If extension.Oid.FriendlyName = "Key Usage" Then
                        Dim ext As X509KeyUsageExtension = CType(extension, X509KeyUsageExtension)
                        Console.WriteLine(ext.KeyUsages)
                    End If

                    If extension.Oid.FriendlyName = "Basic Constraints" Then
                        Dim ext As X509BasicConstraintsExtension = CType(extension, X509BasicConstraintsExtension)
                        Console.WriteLine(ext.CertificateAuthority)
                        Console.WriteLine(ext.HasPathLengthConstraint)
                        Console.WriteLine(ext.PathLengthConstraint)
                    End If

                    If extension.Oid.FriendlyName = "Subject Key Identifier" Then
                        Dim ext As X509SubjectKeyIdentifierExtension = CType(extension, X509SubjectKeyIdentifierExtension)
                        Console.WriteLine(ext.SubjectKeyIdentifier)
                    End If

                    If extension.Oid.FriendlyName = "Enhanced Key Usage" Then
                        Dim ext As X509EnhancedKeyUsageExtension = CType(extension, X509EnhancedKeyUsageExtension)
                        Dim oids As OidCollection = ext.EnhancedKeyUsages
                        Dim oid As Oid
                        For Each oid In oids
                            Console.WriteLine(oid.FriendlyName + "(" + oid.Value + ")")
                        Next oid
                    End If
                Next extension
            Next i
            store.Close()
        Catch
            Console.WriteLine("Information could not be written out for this certificate.")
        End Try

    End Sub
End Module

Observações

As extensões X509 são propriedades dinâmicas e estendidas que podem ser adicionadas a um certificado X509 e alteradas. A X509Extension classe pode ser usada para criar extensões associadas a um certificado, mas que não fazem parte de um certificado emitido por uma autoridade certificadora (CA).

Na sua forma mais básica, uma extensão X509 tem um identificador de objeto (OID), um valor booleano que descreve se a extensão é considerada crítica ou não, e dados codificados em ASN. Extensões personalizadas podem ser registadas num CryptoConfig ficheiro.

O framework .NET inclui implementações de várias extensões comuns do X509:

• X509KeyUsageExtension. Descreve as principais utilizações de um certificado.

• X509BasicConstraintsExtension. Descreve as restrições para um certificado.

• X509EnhancedKeyUsageExtension. Descreve as utilizações melhoradas de chaves de um certificado.

• X509SubjectKeyIdentifierExtension. Descreve o identificador chave. Por exemplo, usado com XMLDSIG.