1775628 - Show the signature date of an OpenPGP-signed email

Status: RESOLVED FIXED

(MailNews Core :: Security: OpenPGP, enhancement)

Description

[Kai Engert [:KaiE:]]

When receiving an email that is signed using OpenPGP, it would be interesting to be able to view the date when the signature was created.

I would like to find an initial implementation that could be added to 102, I found a string that we can reuse.

Comment 1

[Kai Engert [:KaiE:]]

Attachment: Bug 1775628 - Show the signature date of an OpenPGP-signed email. r=aleca

Comment 2

[Kai Engert [:KaiE:]]

Attachment: no-date.png

current implementation, no signature date shown

Comment 3

[Kai Engert [:KaiE:]]

Attachment: with-date.png

signature date showing as implemented by initial patch revision

Comment 4

[Kai Engert [:KaiE:]]

Alex, FYI, usually the time a signature was created matches the time the email was sent.
But it doesn't necessarily have to be that way.

One reason could be an attacker who's trying a replay attack - using an old signature from the past, and resending email with the same content, but with a current email date - trying to trick the recipient. (A statement that was true in the past, at original sender time, might no longer be true now.) I'm wondering if there are legit reasons for the dates to differ - maybe a delay in sending somewhere?

I would like to enable the user to view the signature date. I had needed it myself for debugging once.

Does it make sense to add it in the suggested way, see screenshot, or can you think of a better solution?
Another potential idea is to add a "view signature details" button, which could open a popup that shows the date, and potentially even more technical details.

In theory, we could decide to reject signatures as invalid, if the dates differ. But even in that scenario, the user might still want to see the signature date to understand the issue.

Comment 5

[Alessandro Castellani [:aleca]]

I would like to enable the user to view the signature date. I had needed it myself for debugging once.

I'm not an expert on this, but even your use case makes me think that this is a bit of an edge case scenario, therefore we don't need to always show this front and center and we can find a better way to show this data without adding extra info for an already pretty busy popup.

Another potential idea is to add a "view signature details" button, which could open a popup that shows the date, and potentially even more technical details.

I would suggest to add this info in the "view signature key" popup.

In theory, we could decide to reject signatures as invalid, if the dates differ. But even in that scenario, the user might still want to see the signature date to understand the issue.

This is more a security decision than UX, so I'll defer it to you, maybe in a dedicated bug, if you think it's worth exploring it.

Comment 6

[Kai Engert [:KaiE:]]

(In reply to Alessandro Castellani [:aleca] from comment #5)

I would suggest to add this info in the "view signature key" popup.

That isn't the right place, because the "signature date" isn't a property of the "signature key"
Rather, it's a property of the message.

Here is another, simpler idea.
We could add it after the label that describes whether it's a "good digital signature" or something else.

Comment 7

[Kai Engert [:KaiE:]]

Also, in the expected scenario where the signature date matches the message date, we could keep the date hidden.

Comment 8

[Kai Engert [:KaiE:]]

Alex, I've quickly made an updated patch. I wonder if you think this is acceptable, because it's not requiring more space on screen, and no new strings?

Comment 9

[Kai Engert [:KaiE:]]

Attachment: sigdate.png

Comment 10

[Magnus Melin [:mkmelin]]

Maybe add a row before or after the Signer Key Id? I think it should say what that date is. With the above screenshot I wouldn't understand what the date represents. "Message signed: <date>"

Comment 11

[Kai Engert [:KaiE:]]

(In reply to Magnus Melin [:mkmelin] from comment #10)

Maybe add a row before or after the Signer Key Id? I think it should say what that date is. With the above screenshot I wouldn't understand what the date represents. "Message signed: <date>"

That's what I had originally, but Alex didn't like the extra line. We have an updated suggestion from Alex in phab.

Comment 12

[Kai Engert [:KaiE:]]

I need to re-request review on the phab patch once Alex is back.

Comment 13

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/comm-central/rev/3794574a97c8
Show the signature date of an OpenPGP-signed email. r=aleca