Re: Automatically sign/encrypt messages

[Eric Simon <erik.simon@unine.ch>]

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Hallo Klaus,

Klaus Uhl <news@u-h-l.de> writes:

> The problem is that Gnus separately encrypts a mail for _all_
> recipients and if you have a recipient without a PGP key you will get
> an error message.

Indeed.

> I tried to fix this problem with the following code:
>
> (defun extract-addresses (header-string)
>   (when (not (null header-string))
>     (mapcar #'car (mail-header-parse-addresses header-string))))
> (add-hook
>  'message-send-hook
>  (lambda ()
>    (let* ((to-header (message-fetch-field "To"))
> 	  (cc-header (message-fetch-field "Cc"))
> 	  (bcc-header (message-fetch-field "Bcc"))
> 	  (to (when (not (null to-header)) (substring to-header 3)))
> 	  (cc (when (not (null cc-header)) (substring cc-header 3)))
> 	  (bcc (when (not (null bcc-header)) (substring bcc-header 4)))
> 	  (recipients
> 	   (append (extract-addresses to)
> 		   (extract-addresses cc)
> 		   (extract-addresses bcc))))
>      (cond ((every (lambda (rec)
> 		     (or
> 		      (pgg-lookup-key rec)
> 		      (pgg-fetch-key pgg-default-keyserver-address rec)))
> 		   recipients)
> 	    (mml-secure-message-encrypt-pgpmime))
> 	   (t
> 	    (mml-secure-message-sign-pgpmime))))))
>
> You can see that I read all three headers, strip off the header
> "prefix", extract all addresses and concatenate them to a single
> list. Then I test if _all_ recipients have a PGP key.
>
> The only problem is: it does not work! It always tries to encrypt the
> messages. Does anyone have an idea/suggestion?

It *does* work for email messages, at least for things like a To: with
key and a Cc: without, three To's: with keys, etc etc. Needs testing in
real life for a bit, I'll report any scenario that doesn't work.

Only problem is that it doesn't check for empty recipient anymore, so
when you post in a newgroup, somehow the condition is true: (every
lambda ... recipients) must return true for empty recipient list or
something, need to investigate this.

Anyway, a quick hack that works for me (proof is this message):

(add-hook
 'message-send-hook
 (lambda ()
   (let* ((to-header (message-fetch-field "To"))
	  (cc-header (message-fetch-field "Cc"))
	  (bcc-header (message-fetch-field "Bcc"))
	  (to (when (not (null to-header)) (substring to-header 3)))
	  (cc (when (not (null cc-header)) (substring cc-header 3)))
	  (bcc (when (not (null bcc-header)) (substring bcc-header 4)))
	  (recipients
	   (append (extract-addresses to)
		   (extract-addresses cc)
		   (extract-addresses bcc))))
     (cond ((and (not (null recipients))
		(every (lambda (rec)
		     (or
		      (pgg-lookup-key rec)
		      (pgg-fetch-key pgg-default-keyserver-address rec)))
		   recipients))
	    (mml-secure-message-encrypt-pgpmime))
	   (t
	    (mml-secure-message-sign-pgpmime))))))

I'm sure you can enhance this again :-)

Now thank you for the work in any case and whatever form this code is
going to take, it's going to be very useful to me.

Take care

Eric

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