How can I verify an emails DKIM signature in Python?

Question

Given a raw email, how can I validate the DKIM signature with Python?

Ideally I’d like more than just a pass / fail result, I’d like to know details of any issues.

I’ve found the dkimpy package, but the API isn’t obvious to me.

Answer 1

For a simple pass/fail validation:

import dkim # dkimpy

# Returns True/False
res = dkim.verify(mail_data.encode())

For something more nuanced you can do this:

d = dkim.DKIM(mail_data.encode(), logger=None, minkey=1024, timeout=5, tlsrpt=False)

# 
try:
    d.verify()
    # If it fails, a `dkim.ValidationError` exception will be thrown with details
except dkim.ValidationError as e:
    print(e)

# dkim.ValidationError: body hash mismatch (got b'PXUrNdoTzGcLtd4doJs+CufsiNvxoM5Q3SUPGi00C+I=', expected b'ax9SInd7Z3AQjRzcZSnY6UK392QEvjnKrjhAnsqfDnM=')