(Chilkat2-Python) 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).

Chilkat2 Python Downloads install with pip pip3 install chilkat2 or download... Python Module for Windows, Linux, Alpine Linux, MacOS, Solaris

import sys
import chilkat2

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

imap = chilkat2.Imap()

# Connect to an IMAP server.
# Use TLS
imap.Ssl = True
imap.Port = 993
success = imap.Connect("imap.someMailServer.com")
if (success != True):
    print(imap.LastErrorText)
    sys.exit()

success = imap.Login("myLogin","myPassword")
if (success != True):
    print(imap.LastErrorText)
    sys.exit()

# Select an IMAP mailbox
success = imap.SelectMailbox("Inbox")
if (success != True):
    print(imap.LastErrorText)
    sys.exit()

# Download the 1st email (as MIME) in the Inbox by sequence number.
sbMime = chilkat2.StringBuilder()
success = imap.FetchSingleAsMimeSb(1,False,sbMime)
if (success != True):
    print(imap.LastErrorText)
    sys.exit()

# Load it into a MIME object and check to see if it is signed
mime = chilkat2.Mime()
mime.LoadMimeSb(sbMime)
alreadySavedParts = False
if (mime.ContainsSignedParts() == True):

    # This will save the .p7s and other parts...
    # sa is a CkStringArray
    sa = mime.ExtractPartsToFiles("qa_output")
    if (mime.LastMethodSuccess == True):
        numFiles = sa.Count
        i = 0
        while i < numFiles :
            print("Created: " + sa.GetString(i))
            i = i + 1

        alreadySavedParts = True

# Load the MIME into an Email object.  This unwraps the security layers and verifies signatures.
email = chilkat2.Email()
email.SetFromMimeSb(sbMime)

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.
        # cert is a CkCert
        cert = email.GetSignedByCert()
        if (email.LastMethodSuccess != True):
            print("Failed to get signing certificate object.")
        else:
            print("Signing cert: " + cert.SubjectCN)

else:
    print("Digital signature verification failed.")

if (alreadySavedParts != True):
    email.SaveAllAttachments("qa_output")