During preparations for my GSoC project, I’m finding first traces left by developers who dealt with OpenPGP before. It seems that Florian was right when he noted, that there is a lack of usable higher level Java libraries as I found out when I stumbled across this piece of code. On the other hand I also found a project which thrives to simplify OpenPGP encryption as much as possible. bouncy-gpg – while apparently laying its focus on file encryption and GnuPG compatibility – looks like a promising candidate for Smacks OX module. Unfortunately its code contained some very recent Java features like stream semantics, but I managed to modify its source code to make it compatible down to Androids API level 9, the version Smack is currently targeting. My changes will eventually be upstreamed.
While my next target is now to create a very basic prototype of OX encryption, I’m also reading into OpenKeychains OpenPGP API. It would be very nice to create a universal interface that allows for OX encryption using multiple backends – BouncyCastle on pure Java systems and SpongyCastle / OpenKeychain on Android.
During my work on OX providers for Smack, I stumbled across an interesting issue. When putting a body element as a child into an signcrypt element, the body did not include its namespace, as it is normally only used as child of the message element. Putting it into a signcrypt element made up a special edge case. When a Provider tries to parse the body element, it would falsely interpret the missing namespace as the one of the parent element. Florian provided the solution to this problem by modifying the “toXML()” method of all elements to require an enclosing namespace. Now the body is able to include its namespace in the XML in case the enclosing namespace is different from “jabber:client”.