是否可以使用 MimeKit 创建带有不透明签名的签名电子邮件？

Question

基本上如问题所述。

我编写了一个程序，使用安装在用户计算机上的 X509Certificate2 对电子邮件进行签名。这是用 MimeKit 完成的，这使得它非常容易（如图所示）。

var signer = new CmsSigner(certificate, key);
signer.DigestAlgorithm = DigestAlgorithm.Sha1;

message.Body = MultipartSigned.Create(ctx, signer, messageContent);

有人问我是否可以使用 'opaque' 签名而不是分离签名来创建此签名电子邮件。我相信 OpenSSL 中有一个选项可以做到这一点（？？）。

无论如何，我找不到任何与 MimeKit 相关的 'opaque' 选项。

这可能吗？如果可能，怎么做？

Answer 1

是的，这也是可以的。关于 S/MIME，当人们提到不透明签名时，他们的意思是他们想要 application/pkcs7-mime 格式的签名。以下是您将如何创建它：

var signer = new CmsSigner(certificate, key);
signer.DigestAlgorithm = DigestAlgorithm.Sha1;

message.Body = ApplicationPkcs7Mime.Sign(ctx, signer, messageContent);

希望对您有所帮助！

注：

In late 2013, Microsoft announced that they would be retiring their use of SHA-1 in their products by 2016 with the assumption that its days as an unbroken digest algorithm were numbered. It is speculated that the SHA-1 digest algorithm will be vulnerable to collisions, and thus no longer considered secure, by 2018.

Microsoft and other vendors plan to move to the SHA-2 suite of digest algorithms which includes the following 4 variants: SHA-224, SHA-256, SHA-384, and SHA-512.

Answer 2

public void SignEmail( MimeMessage m, Org.BouncyCastle.X509.X509Certificate certificate, Org.BouncyCastle.Crypto.AsymmetricKeyParameter key, MailboxAddress sender, MimeEntity content)
    {
        var signer = new MimeKit.Cryptography.CmsSigner( certificate, key );
        signer.DigestAlgorithm = DigestAlgorithm.Sha1;

        m.Body = ApplicationPkcs7Mime.Sign( sender, signer.DigestAlgorithm, content );
    }

是否可以使用 MimeKit 创建带有不透明签名的签名电子邮件？

Is it possible to create a signed email with an opaque signature using MimeKit?

c#

smime

mimekit