PK Camera App
Export your GPG key with
gpg2 --export --export-options export-clean,export-minimal --armor [your fingerprint] > passable.key
Then copy passable.key to the root of your SD card.
Each photo will be encrypted with the public key and written to the root of the SD card in the form passable.[data+time in milliseconds]
See Milestones under issues on github.
You are traveling and do not want to be questioned about any photographs you have taken. By leaving the private key at home, it is impossible for you (or anybody else) to decrypt the photographs abroad.
About the logo
The image from the logo is a photo of Hellfire Pass by Ian Armstrong (Flickr ianz) used under CC-BY-SA.