These largely follow the pattern laid out in the secretbox example file. Hopefully they should demonstrate the best ways to use the `box` primitives. Change-Id: I99be5f886e6ffe5f859268d6caa282e263eeacd0 Reviewed-on: https://go-review.googlesource.com/44736 Reviewed-by: Adam Langley <agl@golang.org>