bug#40397: 28.0.50; epg decrypt does not verify signed content in smime

[Sebastian Fieber]

Hey there,

I just thought this may be hard to test as one has to have a smime
certificate to properly receive an encrypted mail.

If someone can point me to the right approach how to fix this I may be
able to dive a bit deeper into the gnus code and submit a bug report.

This is what I have tried now just to get something:

If I alter mm-view-pkcs7-decrypt after the insert epg-decrypt-string to
call something like this:

binqraQklkn3Y.bin
Description: application/emacs-lisp

and adjust mm-view-pkcs7-get-type to handle a third case

binkgDciI_D4h.bin
Description: application/emacs-lisp

and also mm-copy-to-buffer to check for carriage returns like this:

bincB2m4Mh8JI.bin
Description: application/emacs-lisp

(can't send the carriage return properly so \r it is here instead of ^M)

I am able to get an article buffer that still has the base64 encoded
signed blob in it but after it the verified content.

I have no idea where gnus normalizes the line endings to just newlines
and why the mm-view-pkcs7-get-type adjustment is needed. But calling
gnus-ime-display-part is of course not the right approach here. First
there should be some check if the decrypted content needs to be parsed
and handled again but I have no idea which function to write or feed the
decrypted content to.

I hope this may be helpful

Best regards
Sebastian