Under phases-src, you'll find the different templates which are used to generate randomized phases. Each phase (except for the 7th) has 3 pre-defined variations: a, b, and c. In addition, some values are actually randomly generated/selected and hardcoded into the binary when the bomb is generated. These are identified by constants in the templates (e.g SOME_STRING_SET, POSITIVE_GET, LETTER, etc.)
The entire source code for the lab can be found in bomblab.tar. Reviewing how bombs are generated can give you some additional clues, but the phase templates are the most significant thing to have for reverse engineering this project.