AuthenticateAsClient(ClientSecurity) メソッド

セキュアな接続を確立するときにサーバーを認証します。

シンタックス

Visual Basic (宣言)
C#

<SecuritySafeCriticalAttribute()>
<ObsoleteAttribute("Use AuthenticateAsClient(TcpSession) instead.")>
Public Overloads Sub AuthenticateAsClient( _
   ByVal security As ClientSecurity _
)

[SecuritySafeCritical()]
[Obsolete("Use AuthenticateAsClient(TcpSession) instead.")]
public void AuthenticateAsClient( 
   ClientSecurity security
)

パラメータ

security: 認証時に使用されるセキュリティパラメーター。

解説

security.TargetHostはサーバー証明書名に一致する必要があります。認証が失敗した場合は、AuthenticationExceptionが発生します。

証明書を受け入れるか拒否するかをオンザフライで決定するには、Security.ValidationCallback関数を実装します。

クライアント証明書をオンザフライで選択するには、ClientSecurity.SelectionCallback関数を実装します。

使用例

以下のサンプルコードは、AuthenticateAsClientの呼び出しと、証明書の受信時に実行されるコールバックを示します。

//using System.Net.Security;
//using System.Security.Authentication;
//using System.Security.Cryptography.X509Certificates;
  
private void doAuthentication(string server, SslProtocols protocol, bool checkRevocation)
{
    // サーバーを認証し、証明書コールバック関数を指定します。
    ClientSecurity security = new ClientSecurity();
    security.TargetHost = server;
    security.Protocols = protocol;
    security.CheckCertificateRevocation = checkRevocation;
    security.ValidationCallback = certificateReceived;
    myComponent.AuthenticateAsClient(security);
}

private static bool certificateReceived(object sender, X509Certificate certificate, 
    X509Chain chain, SslPolicyErrors sslPolicyErrors)
    {
        // サーバー証明書に問題がない場合、trueを返します。
        if (sslPolicyErrors == SslPolicyErrors.None)
        return true;

    bool acceptCertificate = true;
    string msg = "The server could not be validated for the following reason(s):\r\n";

    // サーバーが証明書を提示しなかった場合
    if ((sslPolicyErrors &
        SslPolicyErrors.RemoteCertificateNotAvailable) == SslPolicyErrors.RemoteCertificateNotAvailable)
    {
        msg = msg + "\r\n    -The server did not present a certificate.\r\n";
        acceptCertificate = false;
    }
    else
    {
        // 証明書がサーバー名と一致しない場合
        if ((sslPolicyErrors &
        SslPolicyErrors.RemoteCertificateNameMismatch) == SslPolicyErrors.RemoteCertificateNameMismatch)
        {
            msg = msg + "\r\n    -The certificate name does not match the authenticated name.\r\n";
            acceptCertificate = false;
        }

        // 証明書に関するその他の問題がある場合
        if ((sslPolicyErrors &
            SslPolicyErrors.RemoteCertificateChainErrors) == SslPolicyErrors.RemoteCertificateChainErrors)
        {
            foreach (X509ChainStatus item in chain.ChainStatus)
            {
                if (item.Status != X509ChainStatusFlags.RevocationStatusUnknown &&
                    item.Status != X509ChainStatusFlags.OfflineRevocation)
                break;

                if (item.Status != X509ChainStatusFlags.NoError)
                {
                    msg = msg + "\r\n    -" + item.StatusInformation;
                    acceptCertificate = false;
                }
            }
        }
    }

    // 検証が失敗した場合、メッセージボックスを表示します。
    if (acceptCertificate == false)
    {
        msg = msg + "\r\nDo you wish to override the security check?";
        if (MessageBox.Show(msg, "Security Alert: Server could not be validated",
            MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation) == DialogResult.Yes)
        acceptCertificate = true;
    }

    return acceptCertificate;
}

Visual Basic

'Imports System.Net.Security
'Imports System.Security.Authentication
'Imports System.Security.Cryptography.X509Certificates
  
Private Sub doAuthentication(ByVal server As String, ByVal protocol As SslProtocols, _
    ByVal checkRevocation As Boolean)
    ClientSecurity security = new ClientSecurity()
    security.TargetHost = server
    security.Protocols = protocol
    security.CheckCertificateRevocation = checkRevocation
    security.ValidationCallback = AddressOf certificateReceived
    myComponent.AuthenticateAsClient(security)
End Sub

Private Shared Function certificateReceived(ByVal sender As Object, ByVal certificate As X509Certificate, _
    ByVal chain As X509Chain, ByVal sslPolicyErrors As SslPolicyErrors) As Boolean
    ' サーバー証明書に問題がない場合、trueを返します。
    If sslPolicyErrors = SslPolicyErrors.None Then
        Return True
    End If

    Dim acceptCertificate As Boolean = True
    Dim msg As String = "The server could not be validated for the following reason(s):" & Constants.vbCrLf

    ' サーバーが証明書を提示しなかった場合
    If (sslPolicyErrors And _
        SslPolicyErrors.RemoteCertificateNotAvailable) = SslPolicyErrors.RemoteCertificateNotAvailable Then
        msg = msg & Constants.vbCrLf & "    -The server did not present a certificate." & Constants.vbCrLf
        acceptCertificate = False
    Else
        ' 証明書がサーバー名と一致しない場合
        If ((sslPolicyErrors And _
            SslPolicyErrors.RemoteCertificateNameMismatch) = SslPolicyErrors.RemoteCertificateNameMismatch) Then
        msg = msg & Constants.vbCrLf & _ 
            "    -The certificate name does not match the authenticated name." & Constants.vbCrLf
        acceptCertificate = False
    End If
            
    ' 証明書に関するその他の問題がある場合
    If (sslPolicyErrors And _
        SslPolicyErrors.RemoteCertificateChainErrors) = SslPolicyErrors.RemoteCertificateChainErrors Then
        For Each item As X509ChainStatus In chain.ChainStatus
            If item.Status <> X509ChainStatusFlags.RevocationStatusUnknown AndAlso _
                item.Status <> X509ChainStatusFlags.OfflineRevocation Then
                Exit For
            End If

            If (item.Status <> X509ChainStatusFlags.NoError) Then
                msg = msg & Constants.vbCrLf & "    -" & item.StatusInformation
                acceptCertificate = False
            End If
            Next item
        End If
    End If

    ' 検証が失敗した場合、メッセージボックスを表示します。
    If acceptCertificate = False Then
        msg = msg & Constants.vbCrLf & "Do you wish to override the security check?"
        If MessageBox.Show(msg, "Security Alert: Server could not be validated", _
            MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation) = System.Windows.Forms.DialogResult.Yes Then
            acceptCertificate = True
        End If
    End If

    Return acceptCertificate
End Function

参照

TcpBase クラス
 TcpBase メンバ
 オーバーロード一覧