1765982 - Inform user if OpenPGP key attributes are ignored because of insecure self-signatures

Status: RESOLVED FIXED

(MailNews Core :: Security: OpenPGP, enhancement)

Description

[Kai Engert (:KaiE:)]

The RNP library may ignore certain attributes of an OpenPGP key, based on the mechanisms used to add those attributes.

For example, if the user added a self-signature to change the expiration date, add or remove subkeys or user IDs, but the self-signature involved the use of the insecure SHA1 hash algorithm, and the action was performed after a well-defined cutoff date, then RNP will ignore those additional attributes.

A recent update (v0.16.0) to the RNP library introduced cutoff dates, and has stopped accepting attributes in the way explained above.

We have seen several reports from users that were affected by this change (shipped with Thunderbird 91.8.0).

For example, the users believe they have sufficiently extended the validity/expiration of their key, and they aren't aware that the software they had used did use security mechanisms that are nowadays considered weak.

The problem is that as of today, Thunderbird will simply ignore those insecure attributes, which confuses users, and doesn't give them any way to understand the cause of the issue.

The suggestion is to introduce an information element in the user interface, when viewing key properties, that tells the users that some key attributes were ignored. This can give users at least a clue how they could research the issue. Possibly we could link to a web page providing more detailed information.

Comment 1

[Magnus Melin [:mkmelin]]

See bug 1763959 comment 7 for how.

Comment 2

[Nickolay Olshevsky]

Some example on how to use RNP API to check for the weak key signatures is added via this PR : https://github.com/rnpgp/rnp/pull/1808

Comment 3

[Nickolay Olshevsky]

Btw, what about extending key view dialog by showing all userids, signatures and subkeys (with some filter options, at least [x] show only self-signatures), marking ones considered as invalid in red (or indicating validity in any other way)?

Comment 4

[Nickolay Olshevsky]

...and, in addition, it is possible via few RNP API calls to allow SHA-1 (or change it's cut-off date for few more years), this may be added as some option in Thunderbird's config or dialog like "Looks like your key/userid is considered as invalid since it uses SHA-1 (MD5) as hash algorithm. Would you like to extend acceptance timeline for SHA-1 (WARNING! It could be insecure!!)?..."

Comment 5

[Kai Engert (:KaiE:)]

Attachment: Bug 1765982 - Show a warning in OpenPGP key properties dialog if there are are ignored unsafe attributes. r=mkmelin

Comment 6

[Kai Engert (:KaiE:)]

I've submitted an initial knowledge base article at
https://support.mozilla.org/en-US/kb/openpgp-weak-key-properties-ignored

I'll update the phabricator patch to include a link to that article in the UI.

Comment 7

[Kai Engert (:KaiE:)]

Attachment: 1765982-esr91-v1.patch

backport for esr91

Comment 8

[Kai Engert (:KaiE:)]

Should be commited soon/today. If nobody commits it within the next few hours, I'll do it.

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/comm-central/rev/5463fcf818ea
Show a warning in OpenPGP key properties dialog if there are are ignored unsafe attributes. r=mkmelin

Comment 10

[Kai Engert (:KaiE:)]

Comment on attachment 9273917 [details]
Bug 1765982 - Show a warning in OpenPGP key properties dialog if there are are ignored unsafe attributes. r=mkmelin

[Approval Request Comment]
Regression caused by (bug #): 1750969
User impact if declined: confused users
Testing completed (on c-c, etc.): manually
Risk to taking this patch (and alternatives if risky): low

Comment 11

[Kai Engert (:KaiE:)]

Comment on attachment 9273917 [details]
Bug 1765982 - Show a warning in OpenPGP key properties dialog if there are are ignored unsafe attributes. r=mkmelin

Wayne already gave me r+ for esr91 uplift in a discussion earlier today.

a=wsmwk from Matrix chat

Comment 12

[Kai Engert (:KaiE:)]

Comment on attachment 9273917 [details]
Bug 1765982 - Show a warning in OpenPGP key properties dialog if there are are ignored unsafe attributes. r=mkmelin

sorry, removing approval, because we need a merged patch for esr91, will work on that now.

Comment 13

[Kai Engert (:KaiE:)]

Attachment: 1765982-esr91-v3.patch

updated esr91 backport patch

Comment 14

[Arvidt]

(In reply to Kai Engert (:KaiE:) from comment #6)

I've submitted an initial knowledge base article at
https://support.mozilla.org/en-US/kb/openpgp-weak-key-properties-ignored

I'll update the phabricator patch to include a link to that article in the UI.

The link shows me "Page Not Found. Sorry, we couldn't find the page you were looking for."

Comment 15

[Kai Engert (:KaiE:)]

The page address was changed as part of the review.

The new URL is:
https://support.mozilla.org/en-US/kb/openpgp-unsafe-key-properties-ignored

Comment 16

[Rob Lemley [:rjl]]

Thunderbird 91.9.0:
https://hg.mozilla.org/releases/comm-esr91/rev/a70417df307f