Verify DomainKey-Signature Headers in Downloaded Email

NODEJS_PRELUDE

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, login, select mailbox..
    // Use TLS 
    imap.Ssl = true;
    imap.Port = 993;
    success = imap.Connect("imap.example.com");
    if (success == true) {
        success = imap.Login("myLogin","myPassword");
        if (success == true) {
            success = imap.SelectMailbox("Inbox");
        }

    }

    if (success !== true) {
        console.log(imap.LastErrorText);
        return;
    }

    // Note: DKIM-Signatures are much more common than DomainKey-Signature
    // See DKIM-Signature Verify Sample.

    var dkim = new chilkat.Dkim();

    // Download a max of 10 emails and verify any DomainKey-Signature headers
    // that are present.

    // Download emails by sequence numbers (not UIDs).
    var bUid = false;
    var seqNum;
    var j;
    var n = imap.NumMessages;
    if (n > 50) {
        n = 50;
    }

    var json = new chilkat.JsonObject();
    json.EmitCompact = false;

    // To verify DomainKey-Signature headers, we need the exact unmodified MIME bytes of each email.
    var mimeData = new chilkat.BinData();
    seqNum = 1;
    while (seqNum <= n) {
        // The FetchSingleBd method was introduced in v9.5.0.76
        success = imap.FetchSingleBd(seqNum,bUid,mimeData);
        if (success !== true) {
            console.log(imap.LastErrorText);
            return;
        }

        // Note: DKIM-Signatures are much more common than DomainKey-Signature
        // See DKIM-Signature Verify Sample.

        // Get the number of DomainKey-Signature headers.
        var numSigs = dkim.NumDomainKeySigs(mimeData);

        // Verify each..
        j = 0;
        while (j < numSigs) {
            console.log("------ DomainKey Signature " + j);

            success = dkim.DomainKeyVerify(j,mimeData);
            if (success !== true) {
                console.log("Not valid.");
                console.log(dkim.LastErrorText);
            }
            else {
                console.log("valid.");
            }

            // Show the additional information about the signature verification
            json.Load(dkim.VerifyInfo);
            console.log(json.Emit());

            // The JSON contains information such as this:

            // 	{
            // 	  "domain": "amazonses.com",
            // 	  "selector": "7v7vs6w47njt4pimodk5mmttbegzsi6n",
            // 	  "publicKey": "MIGfMA0GCSqG...v2GvWPqGHz6uqeQIDAQAB",
            // 	  "canonicalization": "relaxed/simple",
            // 	  "algorithm": "rsa-sha256",
            // 	  "signedHeaders": "Subject:From:To:Date:Mime-Version:Content-Type:References:Message-Id:Feedback-ID",
            // 	  "verified": "yes"
            // 	}

            j = j+1;
        }

        seqNum = seqNum+1;
    }

    success = imap.Disconnect();

}

chilkatExample();