A Blocked Rainbow Table Time-Memory Trade-Off Method.

The rainbow table algorithm has been widely applied to password recovery. However, it faces the issue of too much time or space consumption. Thus in this paper, a blocked rainbow table time-memory trade-off (BRT3) is proposed along with practical implementations. In the new method, the position of each starting point is stored instead of the starting point to reduce the storage consumption. Multiple rainbow blocks are used to reduce the merge probability of chains and improve the success rate of password cracking. A blocked memory structure is adopted to reduce the cryptanalysis time. We also analyze the existing time-memory trade-off methods and carry out comparison experiments to evaluate the performance. The experimental results show that the cryptanalysis time of the BRT3 method is no more than 2 minutes when cracking 200 MS-Windows LM password hashes on a general desktop machine with 2GB memory. What's more, the BRT3 method can also achieve up to a 50% reduction in the storage requirement and acquire an 11% increase in the success rate.