(Node.js) IMAP Download and Verify Signed MIME

Downloads the original MIME of a digitally signed email and saves the .p7s signature along with other MIME parts. It then imports the email into a Chilkat email object to unwrap the S/MIME and verify the signature, and subsequently saves the attachments if they haven't been saved already.

Note: This example requires Chilkat v11.0.0 or greater.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOS

var os = require('os');
if (os.platform() == 'win32') {  
  var chilkat = require('@chilkat/ck-node23-win64'); 
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node23-linux-arm');
    } else if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node23-linux-arm64');
    } else {
        var chilkat = require('@chilkat/ck-node23-linux-x64');
    }
} else if (os.platform() == 'darwin') {
  var chilkat = require('@chilkat/ck-node23-mac-universal');
}

function chilkatExample() {

    var success = false;

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

    var imap = new chilkat.Imap();

    // Connect to an IMAP server.
    // Use TLS
    imap.Ssl = true;
    imap.Port = 993;
    success = imap.Connect("imap.example.com");
    if (success == false) {
        console.log(imap.LastErrorText);
        return;
    }

    success = imap.Login("myLogin","myPassword");
    if (success == false) {
        console.log(imap.LastErrorText);
        return;
    }

    // Select an IMAP mailbox
    success = imap.SelectMailbox("Inbox");
    if (success == false) {
        console.log(imap.LastErrorText);
        return;
    }

    // Download the 1st email (as MIME) in the Inbox by sequence number.
    var sbMime = new chilkat.StringBuilder();
    success = imap.FetchSingleAsMimeSb(1,false,sbMime);
    if (success == false) {
        console.log(imap.LastErrorText);
        return;
    }

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

        // This will save the .p7s and other parts...
        var st = new chilkat.StringTable();
        success = mime.PartsToFiles("c:/temp/qa_output",st);
        if (success == true) {
            var numFiles = st.Count;
            var i = 0;
            while (i < numFiles) {
                console.log("Created: " + st.StringAt(i));
                i = i+1;
            }

            alreadySavedParts = true;
        }

    }

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

    if (email.ReceivedSigned == true) {

        console.log("This email was signed.");

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

            console.log("Signer: " + email.SignedBy);

            // The certificate used for signing may be obtained
            // by calling email.GetSignedByCert.
            var cert = new chilkat.Cert();
            success = email.LastSignerCert(i,cert);
            if (success == false) {
                console.log("Failed to get signing certificate object.");
            }
            else {
                console.log("Signing cert: " + cert.SubjectCN);
            }

        }

    }
    else {
        console.log("Digital signature verification failed.");
    }

    if (alreadySavedParts !== true) {
        email.SaveAllAttachments("c:/temp/qa_output");
    }


}

chilkatExample();