(Chilkat2-Python) Verify DKIM-Signature Headers in Downloaded Email

Downloads email from an IMAP server and verifies the DKIM-Signature header(s) in each email, if present.

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, login, select mailbox..
# Use TLS 
imap.Ssl = True
imap.Port = 993
success = imap.Connect("imap.someMailServer.com")
if (success == True):
    success = imap.Login("myLogin","myPassword")
    if (success == True):
        success = imap.SelectMailbox("Inbox")

if (success != True):
    print(imap.LastErrorText)
    sys.exit()

dkim = chilkat2.Dkim()

# Download a max of 10 emails and verify any DKIM-Signature headers
# that are present.

# Download emails by sequence numbers (not UIDs).
bUid = False

n = imap.NumMessages
if (n > 10):
    n = 10

json = chilkat2.JsonObject()
json.EmitCompact = False

# To verify DKIM-Signature headers, we need the exact unmodified MIME bytes of each email.
mimeData = chilkat2.BinData()
seqNum = 1
while seqNum <= n :
    # The FetchSingleBd method was introduced in v9.5.0.76
    success = imap.FetchSingleBd(seqNum,bUid,mimeData)
    if (success != True):
        print(imap.LastErrorText)
        sys.exit()

    # Get the number of DKIM-Signature headers.
    numDkim = dkim.NumDkimSigs(mimeData)

    # Verify each..
    j = 0
    while j < numDkim :
        print("------ DKIM Signature " + str(j))

        success = dkim.DkimVerify(j,mimeData)
        if (success != True):
            print("Not valid.")
        else:
            print("valid.")

        # Show the additional information about the signature verification
        json.Load(dkim.VerifyInfo)
        print(json.Emit())

        # The JSON contains information such as this:

        # 	{
        # 	  "domain": "amazonses.com",
        # 	  "selector": "7v7vs6w47njt4pimodk5mmttbegzsi6n",
        # 	  "publicKey": "MIGfMA0GCSqG...v2GvWPqGHz6uqeQIDAQAB",
        # 	  "canonicalization": "relaxed/simple",
        # 	  "algorithm": "rsa-sha256",
        # 	  "signedHeaders": "Subject:From:To:Date:Mime-Version:Content-Type:References:Message-Id:Feedback-ID",
        # 	  "verified": "yes"
        # 	}

        j = j + 1

    seqNum = seqNum + 1

success = imap.Disconnect()