Workaround for Exchange-corrupted PGP/Mime structure
I recently received a GPG-encrypted message that notmuch was not able to handle transparently as I'm used to. (That is, instead of decrypting the message and verifying the signature inside, etc.—instead I was just presented with an attachment that contained the encrypted message.) After some poking around, it appears that the problem is that the message was sent through Microsoft Exchange which corrupts PGP/mime structure by changing the outer content-type from "multipart/encrypted" to "multipart/mixed". I've verified this bug by sending mail from notmuch through Exchange as the MTA and it indeed does corrupt the mail in exactly this fashion. It looks like this bug in Exchange is known[1] and there's evidence of other MUAs working around the bug[2]. Have other notmuch users encountered this problem? What would anyone think about a workaround where notmuch-emacs could grub around inside a "multipart/mixed" structure looking for child parts that look like they really should have been a part of a "multipart/encrypted" container? -Carl [1] https://social.technet.microsoft.com/Forums/en-US/c5059734-5031-4d82-96eb-c74fe60b5e9e/quotthis-is-a-broken-pgpmime-message-from-msexchangequot [2] https://gitlab.com/mikecardwell/gpgit/blob/master/gpgit.pl#L108 which also refers to Enigmail having a workaround for thi. signature.asc Description: PGP signature ___ notmuch mailing list notmuch@notmuchmail.org https://notmuchmail.org/mailman/listinfo/notmuch
Re: Workaround for Exchange-corrupted PGP/Mime structure
* Carl Worth: > What would anyone think about a workaround where notmuch-emacs could > grub around inside a "multipart/mixed" structure looking for child > parts that look like they really should have been a part of a > "multipart/encrypted" container? Personally, I see no reason to spend any effort in Notmuch to fix whatever Exchange has screwed up this week. Microsoft has more than enough resources to clean up their own messes, don't you think? -Ralph ___ notmuch mailing list notmuch@notmuchmail.org https://notmuchmail.org/mailman/listinfo/notmuch
Re: Workaround for Exchange-corrupted PGP/Mime structure
Ralph Seichter writes: > * Carl Worth: > >> What would anyone think about a workaround where notmuch-emacs could >> grub around inside a "multipart/mixed" structure looking for child >> parts that look like they really should have been a part of a >> "multipart/encrypted" container? > > Personally, I see no reason to spend any effort in Notmuch to fix > whatever Exchange has screwed up this week. Microsoft has more than > enough resources to clean up their own messes, don't you think? > There's some recent work by dkg in (currrently unreleased) commits on master. "git log -Smangled" d ___ notmuch mailing list notmuch@notmuchmail.org https://notmuchmail.org/mailman/listinfo/notmuch
Re: Workaround for Exchange-corrupted PGP/Mime structure
On Wed, Nov 20 2019, David Bremner wrote: > There's some recent work by dkg in (currrently unreleased) commits on > master. "git log -Smangled" Thanks, David, and Daniel! Those commit messages look very useful to me. I'll update my notmuch and give this a try. -Carl signature.asc Description: PGP signature ___ notmuch mailing list notmuch@notmuchmail.org https://notmuchmail.org/mailman/listinfo/notmuch
Re: Workaround for Exchange-corrupted PGP/Mime structure
On Wed, Nov 20 2019, Carl Worth wrote: > I'll update my notmuch and give this a try. Just a "git pull; make; make install" and my problem went away. Thanks again for the fixes, Daniel. -Carl signature.asc Description: PGP signature ___ notmuch mailing list notmuch@notmuchmail.org https://notmuchmail.org/mailman/listinfo/notmuch
Re: Workaround for Exchange-corrupted PGP/Mime structure
Carl Worth writes: > On Wed, Nov 20 2019, Carl Worth wrote: >> I'll update my notmuch and give this a try. > > Just a "git pull; make; make install" and my problem went away. > > Thanks again for the fixes, Daniel. Yeah, these have been fantastic for me too. MSFT has no intention of fixing PGP or MIME support; it's been well over a decade. ___ notmuch mailing list notmuch@notmuchmail.org https://notmuchmail.org/mailman/listinfo/notmuch
Re: Workaround for Exchange-corrupted PGP/Mime structure
On Wed 2019-11-20 17:10:40 -0500, Brian Sniffen wrote: > Yeah, these have been fantastic for me too. MSFT has no intention of > fixing PGP or MIME support; it's been well over a decade. I'm unwilling to accept this situation, and i hope that other people will join me in exerting pressure on MSFT to fix this. fwiw, there are versions or configurations of Exchange (or of their SMTP/submission subsystem) that *do not* introduce this failure, and I've had some success in getting MSFT to adjust the version or configuration of Exchange used by some clients that can demonstrate that their sent mail is being mangled, to the point where the messages are no longer being mangled. While i've documented the mangling publicly: https://tools.ietf.org/html/draft-dkg-openpgp-pgpmime-message-mangling-00#section-4.1 I would *really* like to see MSFT publicly acknowledge this as a flaw/vulnerability in specific versions/configurations of their products, so that we can push people running vulnerable versions/configurations to upgrade/change. If you know anyone whose messages are being mangled in this way, i would appreciate being put in touch with them, so that i can help them (as a customer) push Microsoft into a better position. If you've encountered any message like this while running notmuch from git master, you should be able to identify those messages with: notmuch search property:index.repaired=mixedup Feel free to reply to me off-list if you have identified anyone who might be interested in trying to improve the situation (or if you yourself are interested in doing this). I might be able to help you figure out specific ways to push Microsoft to avoid causing this failure in the future. --dkg signature.asc Description: PGP signature ___ notmuch mailing list notmuch@notmuchmail.org https://notmuchmail.org/mailman/listinfo/notmuch
Re: Workaround for Exchange-corrupted PGP/Mime structure
On Wed 2019-11-20 13:19:12 -0800, Carl Worth wrote: > On Wed, Nov 20 2019, Carl Worth wrote: >> I'll update my notmuch and give this a try. > > Just a "git pull; make; make install" and my problem went away. > > Thanks again for the fixes, Daniel. Glad that it worked for you! (and, thanks for the pointers to the additional documentation of the problem) --dkg signature.asc Description: PGP signature ___ notmuch mailing list notmuch@notmuchmail.org https://notmuchmail.org/mailman/listinfo/notmuch