Binary Bomb!!!! BOOMMM!!!!

BINARY BOMB - A BOOM at each phase!

A "binary bomb" is a Linux executable C program that consists of six "phases." Each phase expects the user to enter a particular string on stdin. If the user enters the expected string, then that phase
is "defused." Otherwise the bomb "explodes" by printing "BOOM!!!".
The goal is to defuse as many phases as possible without defusing the bomb.

Each bomb phase tests a different aspect of machine language programs:
  Phase 1: string comparison
  Phase 2: loops
  Phase 3: conditionals/switches
  Phase 4: recursive calls and the stack discipline
  Phase 5: pointers
  Phase 6: linked lists/pointers/structs

There is also a "secret phase" that only appears if students append a certain string to the solution to Phase 4. 

Each user gets a unique bomb that they must solve themselves.  The unique
solution to each bomb is available to the instructor.

Catch the source code at Binary Labs: CMU Binary Bomb