(.NET Core C#) IMAP Download and Verify Signed MIME

Downloads the unmodified MIME of a digitally signed email, saves the .p7s signature (and other MIME parts), then loads the email into a Chilkat email object (which unwraps the S/MIME and verifies the signature) and then saves attachments (if the MIME parts were not already saved).

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.Imap imap = new Chilkat.Imap();

// Connect to an IMAP server.
// Use TLS
imap.Ssl = true;
imap.Port = 993;
bool success = imap.Connect("imap.someMailServer.com");
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

success = imap.Login("myLogin","myPassword");
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// Select an IMAP mailbox
success = imap.SelectMailbox("Inbox");
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// Download the 1st email (as MIME) in the Inbox by sequence number.
Chilkat.StringBuilder sbMime = new Chilkat.StringBuilder();
success = imap.FetchSingleAsMimeSb(1,false,sbMime);
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// Load it into a MIME object and check to see if it is signed
Chilkat.Mime mime = new Chilkat.Mime();
mime.LoadMimeSb(sbMime);
bool alreadySavedParts = false;
if (mime.ContainsSignedParts() == true) {

    // This will save the .p7s and other parts...
    Chilkat.StringArray sa = mime.ExtractPartsToFiles("qa_output");
    if (mime.LastMethodSuccess == true) {
        int numFiles = sa.Count;
        int i = 0;
        while (i < numFiles) {
            Debug.WriteLine("Created: " + sa.GetString(i));
            i = i + 1;
        }

        alreadySavedParts = true;
    }

}

// Load the MIME into an Email object.  This unwraps the security layers and verifies signatures.
Chilkat.Email email = new Chilkat.Email();
email.SetFromMimeSb(sbMime);

if (email.ReceivedSigned == true) {

    Debug.WriteLine("This email was signed.");

    // Check to see if the signatures were verified.
    if (email.SignaturesValid == true) {
        Debug.WriteLine("Digital signature(s) verified.");

        Debug.WriteLine("Signer: " + email.SignedBy);

        // The certificate used for signing may be obtained
        // by calling email.GetSignedByCert.
        Chilkat.Cert cert = email.GetSignedByCert();
        if (email.LastMethodSuccess != true) {
            Debug.WriteLine("Failed to get signing certificate object.");
        }
        else {
            Debug.WriteLine("Signing cert: " + cert.SubjectCN);

        }

    }

}
else {
    Debug.WriteLine("Digital signature verification failed.");
}

if (alreadySavedParts != true) {
    email.SaveAllAttachments("qa_output");
}