(Swift 3,4,5...) IMAP Download and Verify Signed (S/MIME) Email

Demonstrates how to download and verify digitally signed S/MIME email.

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

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

    let imap = CkoImap()!

    // Connect to an IMAP server.
    // Use TLS
    imap.ssl = true
    imap.port = 993
    var success: Bool = imap.connect("imap.someMailServer.com")
    if success != true {
        print("\(imap.lastErrorText!)")
        return
    }

    success = imap.login("myLogin", password: "myPassword")
    if success != true {
        print("\(imap.lastErrorText!)")
        return
    }

    // Select an IMAP mailbox
    success = imap.selectMailbox("Inbox")
    if success != true {
        print("\(imap.lastErrorText!)")
        return
    }

    // We can choose to fetch UIDs or sequence numbers.
    var fetchUids: Bool = true

    // Get the message IDs of all the emails in the mailbox
    var messageSet: CkoMessageSet? = imap.search("ALL", bUid: fetchUids)
    if imap.lastMethodSuccess != true {
        print("\(imap.lastErrorText!)")
        return
    }

    // Scan for emails with attachments, and save the attachments
    // to a sub-directory.
    var i: Int = 0
    while i < messageSet!.count.intValue {

        var uid: String? = messageSet!.getId(i).intValue
        print("uid: \(uid!)")

        var email: CkoEmail? = imap.fetchSingle(uid, bUid: true)

        // The security layers of signed and/or encrypted emails
        // are automatically "unwrapped" when loaded into
        // a Chilkat email object.
        // An application only needs to check to see if an email
        // was received signed or encrypted, and then examine
        // the success/failure.  For example:
        if email!.receivedSigned == true {

            print("This email was signed.")

            // Check to see if the signatures were verified.
            if email!.signaturesValid == true {
                print("Digital signature(s) verified.")

                print("Signer: \(email!.signedBy!)")

                // The certificate used for signing may be obtained
                // by calling email.GetSignedByCert.
                var cert: CkoCert? = email!.getSignedByCert()
                if email!.lastMethodSuccess != true {
                    print("Failed to get signing certificate object.")
                }
                else {
                    print("Signing cert: \(cert!.subjectCN!)")
                    cert = nil
                }

            }
            else {
                print("Digital signature verification failed.")
            }

        }

        email = nil

        i = i + 1
    }

    // Disconnect from the IMAP server.
    success = imap.disconnect()

    messageSet = nil

}