CkPython

Check if an Email Was Received Digitally Signed

Demonstrates the read-only Chilkat Email.ReceivedSigned property, which is true if the email was originally received carrying one or more digital signatures. Knowing a message was signed is separate from knowing the signature checked out, so this example also reads SignaturesValid to report whether the signed content verified.

Background: A digital signature on an email (S/MIME) provides two things: authenticity (it was really sent by the holder of a particular certificate) and integrity (the content was not altered in transit). The sender signs a hash of the message with their private key; the recipient verifies it with the sender's public certificate. ReceivedSigned simply tells you a signature is present — verifying it is a separate step exposed through SignaturesValid.

Chilkat CkPython Downloads

Download Chilkat for CkPython

CkPython

import sys
import chilkat

success = False

#  Demonstrates the read-only Email.ReceivedSigned property, which is true if this
#  email was originally received with a digital signature.  Use SignaturesValid to
#  determine whether the signed content actually verified.

email = chilkat.CkEmail()

success = email.LoadEml("qa_data/eml/signed.eml")
if (success == False):
    print(email.lastErrorText())
    sys.exit()

if (email.get_ReceivedSigned() == True):
    print("This email was received with a digital signature.")
    if (email.get_SignaturesValid() == True):
        print("All signatures are valid.")
    else:
        print("One or more signatures are NOT valid.")

else:
    print("This email was not signed.")

#  Note: Paths such as "qa_data/..." are relative local filesystem paths,
#  relative to the current working directory of the running application.