(PureBasic) 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 PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkMime.pb"
IncludeFile "CkImap.pb"
IncludeFile "CkEmail.pb"
IncludeFile "CkStringArray.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkCert.pb"

Procedure ChilkatExample()

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

    imap.i = CkImap::ckCreate()
    If imap.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Connect to an IMAP server.
    ; Use TLS
    CkImap::setCkSsl(imap, 1)
    CkImap::setCkPort(imap, 993)
    success.i = CkImap::ckConnect(imap,"imap.someMailServer.com")
    If success <> 1
        Debug CkImap::ckLastErrorText(imap)
        CkImap::ckDispose(imap)
        ProcedureReturn
    EndIf

    success = CkImap::ckLogin(imap,"myLogin","myPassword")
    If success <> 1
        Debug CkImap::ckLastErrorText(imap)
        CkImap::ckDispose(imap)
        ProcedureReturn
    EndIf

    ; Select an IMAP mailbox
    success = CkImap::ckSelectMailbox(imap,"Inbox")
    If success <> 1
        Debug CkImap::ckLastErrorText(imap)
        CkImap::ckDispose(imap)
        ProcedureReturn
    EndIf

    ; Download the 1st email (as MIME) in the Inbox by sequence number.
    sbMime.i = CkStringBuilder::ckCreate()
    If sbMime.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkImap::ckFetchSingleAsMimeSb(imap,1,0,sbMime)
    If success <> 1
        Debug CkImap::ckLastErrorText(imap)
        CkImap::ckDispose(imap)
        CkStringBuilder::ckDispose(sbMime)
        ProcedureReturn
    EndIf

    ; Load it into a MIME object and check to see if it is signed
    mime.i = CkMime::ckCreate()
    If mime.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkMime::ckLoadMimeSb(mime,sbMime)
    alreadySavedParts.i = 0
    If CkMime::ckContainsSignedParts(mime) = 1

        ; This will save the .p7s and other parts...
        sa.i = CkMime::ckExtractPartsToFiles(mime,"qa_output")
        If CkMime::ckLastMethodSuccess(mime) = 1
            numFiles.i = CkStringArray::ckCount(sa)
            i.i = 0
            While i < numFiles
                Debug "Created: " + CkStringArray::ckGetString(sa,i)
                i = i + 1
            Wend
            CkStringArray::ckDispose(sa)

            alreadySavedParts = 1
        EndIf

    EndIf

    ; Load the MIME into an Email object.  This unwraps the security layers and verifies signatures.
    email.i = CkEmail::ckCreate()
    If email.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkEmail::ckSetFromMimeSb(email,sbMime)

    If CkEmail::ckReceivedSigned(email) = 1

        Debug "This email was signed."

        ; Check to see if the signatures were verified.
        If CkEmail::ckSignaturesValid(email) = 1
            Debug "Digital signature(s) verified."

            Debug "Signer: " + CkEmail::ckSignedBy(email)

            ; The certificate used for signing may be obtained
            ; by calling email.GetSignedByCert.
            cert.i = CkEmail::ckGetSignedByCert(email)
            If CkEmail::ckLastMethodSuccess(email) <> 1
                Debug "Failed to get signing certificate object."
            Else
                Debug "Signing cert: " + CkCert::ckSubjectCN(cert)
                CkCert::ckDispose(cert)

            EndIf

        EndIf

    Else
        Debug "Digital signature verification failed."
    EndIf

    If alreadySavedParts <> 1
        CkEmail::ckSaveAllAttachments(email,"qa_output")
    EndIf



    CkImap::ckDispose(imap)
    CkStringBuilder::ckDispose(sbMime)
    CkMime::ckDispose(mime)
    CkEmail::ckDispose(email)


    ProcedureReturn
EndProcedure