a few GPGME issues
wichert at wiggy.net
Sun Apr 21 15:26:01 CEST 2002
I've been looking at GPGME to see if I can use it to implement a tool
to easily create detached signatures for a large number of files. It
seems to be able to do this but I ran into a few issues that would need
to be resolved before I can get things working
* I need to be able to copy the data buffer with the generated signature
(and modify it, the buffer does not seem to be zero-terminated which is
somewhat unpractical considering it is a string). Since it seems to
be impossible to get the size of the data in a buffer this is impossible.
* In order to conveniently sign a large number of files I have to store the
passphrase in memory. GPGME makes that very hard to do: it tells the
passphrase callback to cleanup after each usage of the passphrase by setting
DESC to NULL, both for succesful and unsuccesful usages. This means I can not
use that to decide to store the passphrase or not. The trick I currently
use is look at the first word in DESC; if that is ENTER I simply feed
GPGME the last used passphrase, and otherwise I (re)prompt the user.
* The GPGME manual does not indicate how the passphrase that the callback
returns is used. Can I be sure that GPGME will never copy it and directly
write it a a passphrase filedescriptor?
* I wanted to use the HOOK data for the passphrase callback to store some
data associated with the callback I am using. However GPGME only has a
function to set the callback and HOOK data but none to retrieve their
current values. This means I need to keep track of that data in another
place as well and create another abstraction layer around GPGME. Can
a function to retrieve that data please be added? This hold for both
passphrase and progess meter callbacks.
* according to the documentation the DESC parameter of the passphrase callback
contains a text `usable to be displayed to the user of the application'.
I fail to see how a combination of numbers and strings without any
documentation what they mean is something you ever want to show to a user.
It woud be useful to be able to get the information contained in DESC
in a simple struct so we can use it in the callback without having
to parse the text.
/wichert at wiggy.net This space intentionally left occupied \
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