Github for PixelKnot

https://github.com/guardianproject/PixelKnot

https://github.com/guardianproject/F5Android

I dug a bit into the code to see how the password, message, and image are encoded and decoded. Not sure how useful it is, seemed reasonably secure. It might be possible to brute force the last 1/3 of the password, since that's used to embed the encrypted message into the image, and I think it has a known text prefix "– PK v 1.0 REQUIRES PASSWORD –". The first 2/3 are hashed and used to encrypt the message.