DKIM.verify() can throw nacl.exceptions.ValueError

[Matthäus Wander]

The following exception caught me by surprise:

  File "/var/www/dkimtest/dkimtester.py", line 159, in analyze_dkim
    valid = d.verify(idx=idx)
  File "/usr/lib/python3/dist-packages/dkim/__init__.py", line 940, in verify
    return self.verify_sig(sig, include_headers, sigheaders[idx], dnsfunc)
  File "/usr/lib/python3/dist-packages/dkim/__init__.py", line 773, in verify_sig
    self.pk, self.keysize, self.ktag, self.seqtlsrpt = load_pk_from_dns(name,
  File "/usr/lib/python3/dist-packages/dkim/__init__.py", line 482, in load_pk_from_dns
    pk, keysize, ktag, seqtlsrpt = evaluate_pk(name, s)
  File "/usr/lib/python3/dist-packages/dkim/__init__.py", line 446, in evaluate_pk
    pk = nacl.signing.VerifyKey(pub[b'p'], encoder=nacl.encoding.Base64Encoder)
  File "/usr/lib/python3/dist-packages/nacl/signing.py", line 69, in __init__
    raise exc.ValueError(
nacl.exceptions.ValueError: The key must be exactly 32 bytes long

The cause is an invalid ed25519 pubkey. I was expecting that DKIM.verify() either returns False or raises a DKIMException.

Is it suppposed to pass through exceptions from nacl?

[Scott Kitterman (kitterman)]

That should be caught as a dkim.KeyFormatError. Thanks.

[Matthäus Wander (mwander)]

Thanks! Fix looks good to me.