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Date: Thu, 25 Jun 2015 14:26:56 -0400
From: Alain Espinosa <alainesp@...ta.cu>
To: john-dev@...ts.openwall.com
Subject: RE: precomputed attacks for john: rainbow tables and
other ways
-------- Original message --------
From: Aleksey Cherepanov <lyosha@...nwall.com>
Date:06/25/2015 12:59 PM (GMT-05:00)
To: john-dev@...ts.openwall.com
Cc:
Subject: [john-dev] precomputed attacks for john: rainbow tables and other ways
...Ideas?
Some weeks ago I research a little about rainbow tables. I need to research more. I will probably add support for Hash Suite in the near future. Some comments:
1- There are a lot of scientific research related to time - memory trade off, the majority unused. We need first to take a look at it and then develop new ideas. For example there are claims that Hellman tables with Distinguished Points are better than Rainbow tables. We can access papers from: http://eprint.iacr.org . I recommend for example "Variants of the Distinguished Point Method for Cryptanalytic Time Memory Trade-offs", 2008, Jin Hong, Kyung Chul Jeong and others.
2- 2^31 is too small. In a high end GPU we can exhaust the key space in 0.14 second for NTLM hashes or 0.25 for MD5. Yes, less than one second.
3- One thing worth investigating is mix rainbow tables with John incremental or Markov mode, so we had a small rainbow table with the more probable candidates. We need to ensure the probability of repetitions remains low, but this is interesting, particularly for high password lengths where full rainbow tables are to big.
Regards,
Alain
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