#1076358 gpgv-sq: fails to verify some good signatures with reason "Bad public key"

Package:
gpgv-sq
Source:
gpgv-sq
Description:
gpgv-like validator for OpenPGP signatures
Submitter:
of1
Date:
2024-11-26 14:57:02 UTC
Severity:
normal
Tags:
#1076358#5
Date:
2024-07-14 23:52:00 UTC
From:
To:
Dear Maintainer,

following this problem resolution:
[SID - Unstable] apt getting an errsig with the microsoft repo
https://forums.debian.net/viewtopic.php?t=159398

gpgv-sq fails to verify some good signatures, at least Microsoft's.


How to reproduce the issue:

$ wget -qP /tmp/ https://packages.microsoft.com/keys/microsoft.asc https://packages.microsoft.com/repos/edge/dists/stable/InRelease
$ gpg -o /tmp/microsoft.gpg --dearmor /tmp/microsoft.asc
$ gpgv-sq --keyring /tmp/microsoft.gpg /tmp/InRelease
gpgv: Signature made Fri Jul 12 19:23:04 2024 +02:00
gpgv:                using RSA key EB3E94ADBE1229CF
gpgv: Can't check signature: Bad public key


The "normal" gpgv validates the signature:

$ gpgv --keyring /tmp/microsoft.gpg /tmp/InRelease
gpgv: Signature made Fri 12 Jul 2024 07:23:04 PM CEST
gpgv:                using RSA key EB3E94ADBE1229CF
gpgv: Good signature from "Microsoft (Release signing) <gpgsecurity@microsoft.com>"

$ gpg -vv --show-keys /tmp/microsoft.gpg
gpg: enabled compatibility flags:
# off=0 ctb=99 tag=6 hlen=3 plen=269
:public key packet:
	version 4, algo 1, created 1446074508, expires 0
	pkey[0]: [2048 bits]
	pkey[1]: [17 bits]
	keyid: EB3E94ADBE1229CF
# off=272 ctb=b4 tag=13 hlen=2 plen=55
:user ID packet: "Microsoft (Release signing) <gpgsecurity@microsoft.com>"
# off=329 ctb=89 tag=2 hlen=3 plen=309
:signature packet: algo 1, keyid EB3E94ADBE1229CF
	version 4, created 1446074508, md5len 0, sigclass 0x13
	digest algo 2, begin of digest 1a 9b
	hashed subpkt 2 len 4 (sig created 2015-10-28)
	hashed subpkt 27 len 1 (key flags: 03)
	hashed subpkt 11 len 5 (pref-sym-algos: 9 8 7 3 2)
	hashed subpkt 21 len 3 (pref-hash-algos: 2 8 3)
	hashed subpkt 22 len 2 (pref-zip-algos: 2 1)
	hashed subpkt 30 len 1 (features: 01)
	hashed subpkt 23 len 1 (keyserver preferences: 80)
	subpkt 16 len 8 (issuer key ID EB3E94ADBE1229CF)
	data: [2047 bits]
pub   rsa2048 2015-10-28 [SC]
      BC528686B50D79E339D3721CEB3E94ADBE1229CF
uid                      Microsoft (Release signing) <gpgsecurity@microsoft.com>
#1076358#10
Date:
2024-07-30 08:41:24 UTC
From:
To:
I also hit this bug, with gpgv-sq 0.10.1-1. My reproducer is similar:

wget -O 0ab215679c571d1c8325275b9bdb3d89ce49ec21.asc \
  'https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x0ab215679c571d1c8325275b9bdb3d89ce49ec21'

wget https://ppa.launchpadcontent.net/mozillateam/ppa/ubuntu/dists/oracular/InRelease

gpg --no-default-keyring --keyring ./somekeyring.gpg --import 0ab215679c571d1c8325275b9bdb3d89ce49ec21.asc

With gpgv from gnupg we have a good signature for 0AB21567...:

$ gpgv --keyring ./somekeyring.gpg InRelease
gpgv: Signature made Tue 30 Jul 2024 07:09:17 AM KST
gpgv:                using RSA key 738BEB9321D1AAEC13EA9391AEBDF4819BE21867
gpgv: Can't check signature: No public key
gpgv: Signature made Tue 30 Jul 2024 07:09:17 AM KST
gpgv:                using RSA key 0AB215679C571D1C8325275B9BDB3D89CE49EC21
gpgv: Good signature from "Launchpad PPA for Mozilla Team"

while with gpgv-sq:

$ gpgv-sq --keyring ./somekeyring.gpg InRelease
gpgv: Signature made Tue Jul 30 07:09:17 2024 +09:00
gpgv:                using RSA key 738BEB9321D1AAEC13EA9391AEBDF4819BE21867
gpgv: Can't check signature: No public key
gpgv: Signature made Tue Jul 30 07:09:17 2024 +09:00
gpgv:                using RSA key 0AB215679C571D1C8325275B9BDB3D89CE49EC21
gpgv: Can't check signature: Bad public key

I'm attaching the files needed to reproduce as above.

Cheers,
#1076358#15
Date:
2024-07-30 10:55:51 UTC
From:
To:
Well, in my case using `gpgv-sq -vv` clarified:

gpgv: Signature made Tue Jul 30 07:09:17 2024 +09:00
gpgv:                using RSA key 0AB215679C571D1C8325275B9BDB3D89CE49EC21
gpgv: Can't check signature: Bad public key
Signing key on 0AB215679C571D1C8325275B9BDB3D89CE49EC21 is not bound:
gpgv:   error: No binding signature at time 2024-07-29T22:09:17Z
gpgv: because: Policy rejected non-revocation signature (PositiveCertification) requiring second pre-image resistance
gpgv: because: SHA1 is not considered secure since 2023-02-01T00:00:00Z

so the signature rejected because of the default policy.
#1076358#20
Date:
2024-08-21 12:48:35 UTC
From:
To:
control: retitle -1 gpgv-sq: fails to verify some good sha1 signatures because of default policy
thanks

hi,

thanks for the bug report and clarifications!

So I guess we should tag this bug "upstream" and "wontfix"?
#1076358#27
Date:
2024-09-11 17:27:18 UTC
From:
To:
control: tags -1 + upstream

Hi, I tagged this bug upstream. I still hope it's not a full wontfix, as
this prevents debootstrapping old Debian and Ubuntu releases, with
release files signed with older (weaker) keys.
#1076358#34
Date:
2024-11-26 14:04:00 UTC
From:
To:
Control: clone -1 -2
Control: reassign -2 apt
Control: tag -1 wontfix

You can override this with a custom security policy:

https://docs.rs/sequoia-policy-config/latest/sequoia_policy_config/

[hash_algorithms]
sha1.second_preimage_resistance = 2026-01-01

The next version of APT will include said policy and apply it
by default to give a grace period of about one year, but as
for gpgv-sq, I think the default behavior makes sense.
#1076358#43
Date:
2024-11-26 14:53:26 UTC
From:
To:
[...]
[...]

for the avoidance of doubt: I agree & thanks Julian!