This is an OpenPGP/GPG (XEP-0027) plugin for Pidgin. This fork is compatible to the Message Carbons (XEP-0280) extension.
Windows users can download a precompiled version of the latest release here: https://github.com/Draghtnod/Pidgin-GPG/releases
apt install libpurple-dev libgpgme11-dev libtool
autoreconf -i
./configure
make
mkdir -p ~/.purple/plugins
cp src/.libs/pidgin_gpg.so ~/.purple/plugins/
Select Tools > Plugins, and enable the OpenPGP/GPG plugin. Select configure and choose your GPG key.
Your OpenPGP/GPG agent needs to be enabled for this plugin to work properly. You may need to restart pidgin to be prompted for the key passphrase after enabling this plugin.
This is not the official branch. I'm maintianing this fork simply for maintenence. I'm am not actively developing pidgin-gpg, maintly making sure it keeps working and building. Releases > 0.9 should not be confused with those of the original author (though the original author seems to have stopped all development).