[tialaramex]

I should actually fix this. What I've described above is basic "chaining", but Rainbow Tables are a further improvement still by Philippe Oechslin. The additional insight in Rainbow Tables is that we can reduce collisions in our hash-pass-hash-pass back and forth if we modify that pass function so that its behaviour varies by depth, this way if a collision occurs but at different depths in different chains (e.g. maybe the chain starting with password "password" hashes immediately to 5f4dcc but in another chain the value 5f4dcc is found for the password "j58X_m04" after six steps) the next call to pass() will diverge again, so the collision only wastes a small fraction of our precomputation effort. If the collision does happen at the same place in the chain, the final hash output will be identical to another chain, so it's easy to discover this problem and apply whichever mitigation seems appropriate.