让Outlook识别我的数字签名电子邮件

Question

我正在使用C#.NET 4.0发送签名的SMTP邮件,如下所示:

    private void SendMailMessage(object data)
    {
        MailMessage message = new MailMessage();
        message.From = new MailAddress(fromAddress);
        message.To.Add(new MailAddress(emailTo));
        message.Subject = "Subject";
        message.IsBodyHtml = true;
        message.Body += "Blah blah blah.";
        byte[] messageBytes = Encoding.ASCII.GetBytes(message.Body);
        SignedCms Cms = new SignedCms(new ContentInfo(messageBytes));
        CmsSigner Signer = new CmsSigner(SubjectIdentifierType.IssuerAndSerialNumber, certificate);
        Cms.ComputeSignature(Signer);
        byte[] SignedBytes = Cms.Encode();
        MemoryStream signedStream = new MemoryStream(SignedBytes);
        AlternateView signedView = new AlternateView(signedStream, "application/pkcs7-mime; smime-type=signed-data;name=sig.p7m");
        message.AlternateViews.Add(signedView);
        SmtpClient client = new SmtpClient(smtpServer, int.Parse(smtpServerPort));
        client.DeliveryMethod = SmtpDeliveryMethod.Network;
        client.Send(message);
        message.Dispose();
        client = null;       
    }

据我所知,这"工作",如果查看消息的原始数据,我会看到备用视图中有一个大的PKCS签名.但Outlook不承认它.Outlook客户端通常会识别已签名的邮件并尝试验证它们,并在邮件上放置一些证书以及所有这些...

我想要那......我错过了什么？

编辑:我自己在这方面取得了一些进展,但仍然遇到了一些麻烦.这是代码现在的样子:

    private void SendMailMessage(string emailTo)
    {            
        MailMessage message = new MailMessage();
        message.From = new MailAddress(fromAddress);
        message.To.Add(new MailAddress(emailTo));
        message.Subject = "Special Delivery";
        message.IsBodyHtml = false;
        string body = "Content-Type: text/plain;charset=\"iso-8859-1\"\nContent-Transfer-Encoding: quoted-printable\n\nHere is some body text!";
        byte[] messageBytes = Encoding.ASCII.GetBytes(body);
        ContentInfo content = new ContentInfo(messageBytes);
        SignedCms signedCms = new SignedCms(content, false);
        CmsSigner Signer = new CmsSigner(SubjectIdentifierType.IssuerAndSerialNumber, certificate);
        signedCms.ComputeSignature(Signer);
        byte[] signedBytes = signedCms.Encode();
        MemoryStream ms = new MemoryStream(signedBytes);
        AlternateView av = new AlternateView(ms, "application/pkcs7-mime; smime-type=signed-data;name=smime.p7m");
        message.AlternateViews.Add(av);
        SmtpClient client = new SmtpClient(smtpServer, int.Parse(smtpServerPort));
        client.DeliveryMethod = SmtpDeliveryMethod.Network;
        client.Send(message);
        message.Dispose();
        client = null;
    }

值得注意的是,我留下了留言.这次是空白,只发送了AlternateView.现在,当我将其发送到Outlook收件箱时,我在我的电子邮件中获得了挂锁图标,S/MIME doodad启动并尝试验证签名者,但失败了.用于签署电子邮件的证书由公开信任的CA颁发. 编辑:这是我的错,证书没有"安全电子邮件"使用属性.我会得到一张新证书.

当我将同一封电子邮件发送到Gmail地址时,我收到一条空白消息,其中包含*.p7m附件,其中包含一堆垃圾.

Answer 1

在Outlook中使用此代码的代码如下所示:

private void SendMailMessage(string emailTo)
{
    MailMessage message = new MailMessage();
    message.From = new MailAddress(fromAddress);
    message.To.Add(new MailAddress(emailTo));
    message.Subject = "Regarding your lottery winnings";
    message.IsBodyHtml = false;
    string body = "Content-Type: text/plain;charset=\"iso-8859-1\"\nContent-Transfer-Encoding: quoted-printable\n\nBlah blah blah blah blah blah.";                
    byte[] messageBytes = Encoding.ASCII.GetBytes(body);
    ContentInfo content = new ContentInfo(messageBytes);
    SignedCms signedCms = new SignedCms(content, false);
    CmsSigner Signer = new CmsSigner(SubjectIdentifierType.IssuerAndSerialNumber, emailCert);
    signedCms.ComputeSignature(Signer);
    byte[] signedBytes = signedCms.Encode();
    MemoryStream ms = new MemoryStream(signedBytes);
    AlternateView av = new AlternateView(ms, "application/pkcs7-mime; smime-type=signed-data;name=smime.p7m");
    message.AlternateViews.Add(av);                
    SmtpClient client = new SmtpClient(smtpServer, int.Parse(smtpServerPort));
    client.DeliveryMethod = SmtpDeliveryMethod.Network;
    client.Send(message);
    message.Dispose();
    client = null;
}

当然,使用有效的证书.现在,当我发送此电子邮件并在Outlook中查看时,我在电子邮件中获得了证书图标,并且S/MIME控件成功验证了签名,文本显示就像我想要的那样而不向用户显示标题.

请注意,我必须留下message.Body为空.把任何东西放在消息中.身体会打破它.