1629309 - OpenPGP public key email attachments should use a reduced key, that excludes signatures from others

Status: RESOLVED FIXED

(MailNews Core :: Security: OpenPGP, enhancement)

Description

[Kai Engert (:KaiE:)]

A public key can be quite large, if it contains many signatures made by other people (key certifications).

When automatically appending the user's own public key (because we're sending a signed message), we should probably send the minimal version. This requires stripping off signatures with RNP, which depends on upstream https://github.com/rnpgp/rnp/issues/1006

We need to figure out a way for the user to optionally send the full public key.

Comment 1

[Kai Engert (:KaiE:)]

See also bug 1628097 comment 14

Comment 2

[pbrandao]

Option could be also not to send any key as per bug 1645514

Comment 3

[Michael Nüsken]

What about keyservers? My keys are there and a pointer would do.

Comment 4

[Magnus Melin [:mkmelin]]

Just because you are technical enough to get them uploaded to a keyserver that doesn't mean the average user would have any clue.

Comment 5

[Michael Nüsken]

True. But tb could be clever enough to find it there.

Comment 6

[Magnus Melin [:mkmelin]]

It can already find keys from a keyserver. But we don't upload keys - which is its own can of worms.

Comment 7

[Nicolas Falquet]

I understand that sending minimum keys is now possible since TB 91 and bug#1713664.

See https://github.com/rnpgp/rnp/pull/1433.

Comment 8

[Michael Nüsken]

Maybe off-topic, but closely related: In case I use S/MIME for signing instead, what about attaching the used S/MIME certificate similarly? I do not see anything thelike in the menus.

Comment 9

[Magnus Melin [:mkmelin]]

When you sign with S/MIME the recipient automatically get your certificate at the same time.

Comment 10

[Kai Engert (:KaiE:)]

I think that by default we should minimize.
We recently added code to minimize in a different scenario:
https://hg.mozilla.org/comm-central/rev/58bcd5abe85a22c9d73f2abbacee8c3e89b02f23

It should be easy to also fix this bug using that new code.

Comment 11

[Kai Engert (:KaiE:)]

Suggestion as an intermediary solution, without introducing new UI.

For the automatic key attachment, we always use the reduced key (keep user IDs, keep all self-signatures, but strip all foreign signatures).

For all existing mechanisms used to explicitly copy/export/send a key, we continue to use the full key.

Comment 12

[Kai Engert (:KaiE:)]

Attachment: Bug 1629309 - Send reduced size OpenPGP when automatically attaching to emails. r=mkmelin

Comment 13

[Kai Engert (:KaiE:)]

Attachment: 1629309-esr102.patch

Comment 14

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/comm-central/rev/37b5215866bc
Send reduced size OpenPGP when automatically attaching to emails. r=mkmelin

Comment 15

[Kai Engert (:KaiE:)]

Comment on attachment 9280475 [details] [diff] [review]
1629309-esr102.patch

[Approval Request Comment]
Regression caused by (bug #): no
User impact if declined: unnecessarily big email attachments with signed/encrypted email
Testing completed (on c-c, etc.): yes
Risk to taking this patch (and alternatives if risky): low

Comment 16

[Wayne Mery (:wsmwk)]

(In reply to Kai Engert (:KaiE:) from comment #15)

Comment on attachment 9280475 [details] [diff] [review]
1629309-esr102.patch

Kaie, is same patch for both beta and 102?

Comment 17

[Wayne Mery (:wsmwk)]

Comment on attachment 9280475 [details] [diff] [review]
1629309-esr102.patch

[Triage Comment]
Approved for beta (102)

Comment 18

[Rob Lemley [:rjl]]

Thunderbird 102.0b5:
https://hg.mozilla.org/releases/comm-beta/rev/da7930dd294f