We've awarded one NERF gun prize to the first finisher, @trapflag, and a second to Robert Miller, who was randomly chosen (using a hardware random number generator made from coins and playing cards) from the 19 other successful solvers.
Winners, please email me to let me know where to send the prizes.
For those of you who didn't finish, here's how to do it:
(Enjoy this video? Check out more on the SophosLabs YouTube channel.)
The second stage of this puzzle involved writing code to perform a cryptographic brute force attack; although there were numerous optimisations you could apply, there were no short cuts.
That means that you really had to back yourself that your code was correctly written - so well done to all who took part, and especially to the 20 of you who cracked the puzzle in time.