(Tcl) IMAP Download and Verify Signed MIME

Downloads the original MIME of a digitally signed email and saves the .p7s signature along with other MIME parts. It then imports the email into a Chilkat email object to unwrap the S/MIME and verify the signature, and subsequently saves the attachments if they haven't been saved already.

Note: This example requires Chilkat v11.0.0 or greater.

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load ./chilkat.dll

set success 0

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

set imap [new_CkImap]

# Connect to an IMAP server.
# Use TLS
CkImap_put_Ssl $imap 1
CkImap_put_Port $imap 993
set success [CkImap_Connect $imap "imap.example.com"]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkImap $imap
    exit
}

set success [CkImap_Login $imap "myLogin" "myPassword"]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkImap $imap
    exit
}

# Select an IMAP mailbox
set success [CkImap_SelectMailbox $imap "Inbox"]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkImap $imap
    exit
}

# Download the 1st email (as MIME) in the Inbox by sequence number.
set sbMime [new_CkStringBuilder]

set success [CkImap_FetchSingleAsMimeSb $imap 1 0 $sbMime]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkImap $imap
    delete_CkStringBuilder $sbMime
    exit
}

# Load it into a MIME object and check to see if it is signed
set mime [new_CkMime]

CkMime_LoadMimeSb $mime $sbMime
set alreadySavedParts 0
if {[CkMime_ContainsSignedParts $mime] == 1} then {

    # This will save the .p7s and other parts...
    set st [new_CkStringTable]

    set success [CkMime_PartsToFiles $mime "c:/temp/qa_output" $st]
    if {$success == 1} then {
        set numFiles [CkStringTable_get_Count $st]
        set i 0
        while {$i < $numFiles} {
            puts "Created: [CkStringTable_stringAt $st $i]"
            set i [expr $i + 1]
        }
        set alreadySavedParts 1
    }

}

# Load the MIME into an Email object.  This unwraps the security layers and verifies signatures.
set email [new_CkEmail]

CkEmail_SetFromMimeSb $email $sbMime

if {[CkEmail_get_ReceivedSigned $email] == 1} then {

    puts "This email was signed."

    # Check to see if the signatures were verified.
    if {[CkEmail_get_SignaturesValid $email] == 1} then {
        puts "Digital signature(s) verified."

        puts "Signer: [CkEmail_signedBy $email]"

        # The certificate used for signing may be obtained
        # by calling email.GetSignedByCert.
        set cert [new_CkCert]

        set success [CkEmail_LastSignerCert $email $i $cert]
        if {$success == 0} then {
            puts "Failed to get signing certificate object."
        }         else {
            puts "Signing cert: [CkCert_subjectCN $cert]"
        }

    }

} else {
    puts "Digital signature verification failed."
}

if {$alreadySavedParts != 1} then {
    CkEmail_SaveAllAttachments $email "c:/temp/qa_output"
}


delete_CkImap $imap
delete_CkStringBuilder $sbMime
delete_CkMime $mime
delete_CkStringTable $st
delete_CkEmail $email
delete_CkCert $cert