Date: Mon, 29 Jun 2015 17:36:42 -0400 From: Alain Espinosa <alainesp@...ta.cu> To: john-dev@...ts.openwall.com Subject: Re: Re: precomputed attacks for john: rainbow tables and? other ways -------- Original message -------- From: Aleksey Cherepanov <lyosha@...nwall.com> Date:06/29/2015 4:54 PM (GMT-05:00) To: john-dev@...ts.openwall.com Cc: Subject: Re: [john-dev] Re: precomputed attacks for john: rainbow tables and? other ways ...I do not really get your algorithm There is no new algorithm. I propose standard Hellman tables with distinguished points (DP). The difference is that I propose to use only one table instead of n or l or t (there are different notation) different tables. In rainbow terminology is using only one color. ...let's end chains based on hash value, for instance end chain if hash has 2 leading zero bytes; This is exactly how DP works. ...this way we compute (number of colors)*(chain length) hashes but check only (number of colors) hashes against the table In rainbow tables: - (number of colors)==(chain length) - We compute ((number of colors)^2)/2 hashes. Instead what I suggest calculate only (number of colors). - We check (number of colors) hashes against the table in disk or ram. Instead what I suggest check only one time. Why was not used before then? I am not sure. DP can't merge easily with rainbow tables, that are the more used TMTO. Only one Hellman table generate to much duplicate - merges that hit performance. Only Hellman tables with DP can easily eliminate the duplicates. Also using only one table considerably increase the offline precomputation time. When I say isn't parallelizable I mean the online phase. The offline is very parallel, even GPU friendly. Regards, Alain Content of type "text/html" skipped
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