我正在使用C# .NET 4.0发送一个签名的SMTP邮件,代码如下:
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,这在某种程度上是“可行的”,因为如果查看消息的原始数据,可以看到其中一个大的PKCS签名的备选视图。但是Outlook并不承认它。Outlook客户端通常会识别已签名的消息,并尝试验证它们,并在消息上放置一个小证书等等...
我想要那个... 我还缺少什么?
编辑:我自己在这方面取得了一些进展,但仍然遇到一些麻烦。现在代码看起来像这样:
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,这次我留空了消息正文 message.Body,仅发送了 AlternateView。现在,当我将其发送到 Outlook 邮箱时,会在我的电子邮件上显示一个挂锁图标,S/MIME 小玩意儿会尝试验证签名者,但失败了。用于签署电子邮件的证书由公共可信 CA 发行。 编辑:这是我的问题,证书没有“安全电子邮件”使用属性。我会获取新的证书。
当我将相同的电子邮件发送到 Gmail 地址时,我会收到一个带有*.p7m附件的空白消息,其中包含一堆垃圾。