X509Extension 類別

定義

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

繼承

Object

AsnEncodedData

X509Extension

衍生

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

更多…

範例

以下程式碼範例示範如何使用該 X509Extension 類別。

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

備註

X509 擴充功能是動態且可擴充的屬性，可以加入並變更於 X509 憑證中。 此 X509Extension 類別可用於建立與憑證相關聯但不屬於由認證機構（CA）核發的憑證中的擴充。

在最基本的形式中，X509 擴充包含物件識別碼（OID）、描述該擴充是否被視為關鍵的布林值，以及 ASN 編碼的資料。 自訂副檔名可以在檔案中註冊 CryptoConfig 。

.NET 框架包含了數個常見 X509 擴充功能的實作：

• X509KeyUsageExtension。 描述憑證的關鍵用途。

• X509BasicConstraintsExtension。 描述憑證的限制條件。

• X509EnhancedKeyUsageExtension。 描述憑證的增強金鑰使用方式。

• X509SubjectKeyIdentifierExtension。 描述金鑰識別碼。 例如，搭配 XMLDSIG 一起使用。