(Go) 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).

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

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

    imap := chilkat.NewImap()

    // Connect to an IMAP server.
    // Use TLS
    imap.SetSsl(true)
    imap.SetPort(993)
    success := imap.Connect("imap.someMailServer.com")
    if success != true {
        fmt.Println(imap.LastErrorText())
        imap.DisposeImap()
        return
    }

    success = imap.Login("myLogin","myPassword")
    if success != true {
        fmt.Println(imap.LastErrorText())
        imap.DisposeImap()
        return
    }

    // Select an IMAP mailbox
    success = imap.SelectMailbox("Inbox")
    if success != true {
        fmt.Println(imap.LastErrorText())
        imap.DisposeImap()
        return
    }

    // Download the 1st email (as MIME) in the Inbox by sequence number.
    sbMime := chilkat.NewStringBuilder()
    success = imap.FetchSingleAsMimeSb(1,false,sbMime)
    if success != true {
        fmt.Println(imap.LastErrorText())
        imap.DisposeImap()
        sbMime.DisposeStringBuilder()
        return
    }

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

        // This will save the .p7s and other parts...
        sa := mime.ExtractPartsToFiles("qa_output")
        if mime.LastMethodSuccess() == true {
            numFiles := sa.Count()
            i := 0
            for i < numFiles {
                fmt.Println("Created: ", *sa.GetString(i))
                i = i + 1
            }

            sa.DisposeStringArray()
            alreadySavedParts = true
        }

    }

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

    if email.ReceivedSigned() == true {

        fmt.Println("This email was signed.")

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

            fmt.Println("Signer: ", email.SignedBy())

            // The certificate used for signing may be obtained
            // by calling email.GetSignedByCert.
            cert := email.GetSignedByCert()
            if email.LastMethodSuccess() != true {
                fmt.Println("Failed to get signing certificate object.")
            }
            else {
                fmt.Println("Signing cert: ", cert.SubjectCN())
                cert.DisposeCert()
            }

        }

    }
    else {
        fmt.Println("Digital signature verification failed.")
    }

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


    imap.DisposeImap()
    sbMime.DisposeStringBuilder()
    mime.DisposeMime()
    email.DisposeEmail()