> If I need to exchange encrypted messages in some store and forward style I'd likely use PGP.

Do you or others have any recommendations for cross-platform library code (at least OSX, Windows, Android, Linux, Windows 8) for this purpose?

I may have understood incorrectly, but I thought that using gpg from code required launching a sub-process (e.g. via gpgme). That makes me very nervous from a library point of view, perhaps I'm wrong to be nervous.

Is the answer still "use PGP/GPG" or is there somewhere else I could look to avoid home-made cryptosystem here?