It looks like the latest version of libgcrypt (1.6.0) is incompatible with encrypt. The functions for getting a list of supported algorithms (both cipher and hash) have been removed/renamed. This is currently limited to GNU/Linux systems, although it could soon affect Macs (as and when libgcrypt is updated in Homebrew).
I suppose this might persuade us to specify exact version numbers in the list of dependencies (but we'll see).
We should be able to rewrite encrypt to make use of the newer version of the library, and will release an update for GNU/Linux systems as soon as possible - hopefully this coming weekend.
Sorry for any inconvenience,