notmuch-show: Verification via epa-verify-region affected by formatting hooks

[David Bremner]

Rainer Gemulla <rgemulla at gmx.de> writes:

> Hi all,
>
> when a message contains an text/plain part that is signed via inline pgp and shown in notmuch-show-mode, verification of that part's signature via epa-mail-verify or epa-verify-region fails. 
>
> The reason is that the hooks in notmuch-show-insert-text/plain-hook modify the text (and thus the signature becomes invalid). Calling notmuch-show-pipe-part with "gpg --verify" works as expected and verifies the correctness of the signature.
>
> Not sure what to do about this, but I find the current behavior confusing. The notmuch emacstips documentation also (implicitly) states that verification of inline pgp can be done via the epa-* functions. 
>

That documentation is wiki. That means both that you should take it with
a grain of salt, and that we welcome updates to it

  https://notmuchmail.org/wikiwriteaccess/
  
> One option may be to document this behavior. Another one to add a
> function like notmuch-crypto-verify-part (which is what I currently
> do).

I suppose that you could also customize notmuch-show-insert-text/plain-hook

> And/or one may be verify each inline pgp signature part by
> default (when crypto processing is enabled) and add a "crypto button".

As far as documentation in the wiki there is a FAQ about (non) support
for inline PGP. I think dkg (in copy) was working on decryption of
inline PGP, but explicitely not on verifying signatures. You can read a
summary of his issues with inline PGP signatures at

        https://dkg.fifthhorseman.net/notes/inline-pgp-harmful/