Rainbow tables is basically a huge table upwards of a few hundred GB (bigger the better) of possible hashes with given combinations such as Capital letters, lowercase letters, numbers, etc. It is quicker to just check the hash against a list of hashes than to generate a hash from a normal password in realtime. Used with brute forcing only, and if you want you can generate the tables yourself if you have a big harddrive and willing to use up a huge chunk of it to check out these tables more. You can even buy these tables already on external drives for 300 bucks of the net easily if you do a google.
The chances of them getting past the encryption is slim to none, unless they decide that the cost of renting a supercomputer is less than the money they could make selling the CC info.
Here is some more info if you are interested: