Rust

Verify DKIM-Signature Headers in Downloaded Email

See more DKIM / DomainKey Examples

Downloads email from an IMAP server and verifies the DKIM-Signature header(s) in each email, if present. Rust

let mut success = false;

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

let imap = chilkat::Imap::new();

// Connect to an IMAP server, login, select mailbox..
// Use TLS 
imap.set_ssl(true);
imap.set_port(993);
success = imap.connect("imap.example.com").is_ok();
if success {
    success = imap.login("myLogin", "myPassword").is_ok();
    if success {
        success = imap.select_mailbox("Inbox").is_ok();
    }

}

if !success {
    println!("{}", imap.last_error_text());
    return;
}

let dkim = chilkat::Dkim::new();

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

// Download emails by sequence numbers (not UIDs).
let b_uid = false;
let mut seq_num: i32 = 0;
let mut j: i32 = 0;
let mut n = imap.num_messages();
if n > 10 {
    n = 10;
}

let json = chilkat::JsonObject::new();
json.set_emit_compact(false);

// To verify DKIM-Signature headers, we need the exact unmodified MIME bytes of each email.
let mime_data = chilkat::BinData::new();
seq_num = 1;
while seq_num <= n {
    // The FetchSingleBd method was introduced in v9.5.0.76
    if imap.fetch_single_bd(seq_num as u32, b_uid, &mime_data).is_err() {
        println!("{}", imap.last_error_text());
        return;
    }

    // Get the number of DKIM-Signature headers.
    let num_dkim = dkim.num_dkim_sigs(&mime_data);

    // Verify each..
    j = 0;
    while j < num_dkim {
        println!("------ DKIM Signature {}", j);

        if dkim.dkim_verify(j, &mime_data).is_err() {
            println!("Not valid.");
        } else {
            println!("valid.");
        }

        // Show the additional information about the signature verification
        let _ = json.load(&dkim.verify_info());
        println!("{}", json.emit().unwrap_or_default());

        // 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;
    }

    seq_num = seq_num + 1;
}

success = imap.disconnect().is_ok();