This guide is contributed by our nice Windows maintainer DJm00n.
LeechCraft doesn't work with Cygwin GnuPG. Instead it works with native GnuPG build. If you understand the difference you probably already have the right version.
Later LeechCraft builds for Windows support message encryption, particularly via XMPP (the XEP-0027). Native GnuPG build called Gpg4win is required for this to function properly. Gpg4win can be obtained here.
After installation you need to generate a pair of keys — public and private (secret) ones. Your public key will be used by others to encrypt messages addressed to you, which could be decrypted by you using the private key. For this one can use the GNU Privacy Assistant application from Gpg4win. After keys are generated you need to give your public key to your chat buddies.
You can also add public keys of your chat buddies using that same program, GNU Privacy Assistant. This is needed for LeechCraft to encrypt messages you write. Ask your buddies to send you their public keys via any method convenient to them, from email to XMPP file transfer.
After you've generated your keys and imported public keys of your contacts, LeechCraft needs to be configured for this to work.
Incoming messages decryption
Open LeechCraft settings: Main Menu → Settings → Azoth.
Select account you wish to configure and press the PGP... button on the right. Select your private key in the drop-down list which will be used to encrypt incoming messages and press OK. Then press Apply for settings to take effect.
Outgoing messages encryption
Each user can be assigned with a public PGP key, which will be used for encrypting the messages for that user.
For assigning a public key, you need to:
- Right-click the user in Azoth roster.
- Select Manage PGP keys... in the context menu.
- Choose the public key for the contact and press OK.
Using encrypted messaging
One can enable or disable message encryption before sending the message.
To toggle the encryption, one needs to press the Enable encryption button in the chat tab's toolbar (a lock is drawn on it). After that all your messages will be encrypted with the chosen public key for that contact, and the other part will be able to read the messages only if it has the corresponding private key. It's up to the other party, though, whether to send you back encrypted or plain messages.
If something goes wrong, the button won't be enabled and you'd get an error message instead.
Also, LeechCraft automatically enables sending encrypted messages if it receives an encrypted message from the other part and a public key for it is set.
There is an excellent page about common problems and their solutions on the Psi IM project page here.