Date: Tue, 29 Aug 2006 15:11:17 +0200 From: Simon Marechal <simon@...quise.net> To: john-users@...ts.openwall.com Subject: Re: Using a pre-computed list of alphanumeric strings. (not rainbow tables) John wrote: > Why would you have to generate that for every salt? When you have a word > list, its just plain text dictionary file, and John uses that. "if I have a pre-computed hash table with hashes of every alphanumeric combination up to say, 14 chars long, why couldn't something like this be used in place of a word list?" You can only compute the hash WITH the salt. For some ciphers you can compute a pre-hashed value that would save some cycles. But most of the time you can't. > I guess I overlooked something.....when I was cracking NT hashes with > pre-generated rainbow tables.... I could do it fast and effectively because > the hash could be broken into two 7 char strings, so really you are only > cracking 7 chars at a time....a MUCH smaller list then having a table of > all > possible 14char alphanumeric combinations.... It's because of that, plus the fact that lm hashes do not care about case. More importantly, rainbow tables are not lists of all 7 chars combinations. They are ordered tables of hash-chains. They are a very effective time-memory trade-off, and do not allow finding 100% of the 7 chars cleartexts. Here is a more accurate description: http://en.wikipedia.org/wiki/Rainbow_table -- To unsubscribe, e-mail john-users-unsubscribe@...ts.openwall.com and reply to the automated confirmation request that will be sent to you.
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