Date: Wed, 18 May 2011 19:29:58 -0400 From: Brad Tilley <brad@...ystems.com> To: john-users@...ts.openwall.com Subject: Re: Help with 14 - 16 digit CC's stored in MD5 hash On 05/18/2011 12:45 PM, Kevin Finisterre wrote: > Can anyone direct me to optimal configuration settings for JtR when attempting to reverse credit card information that is stored in MD5 hashes? The numbers are assumed to be 14-16 digits in length. > > Theory associated with what I would like to accomplish"is can be found here. > http://www.integrigy.com/security-resources/whitepapers/Integrigy_Hashing_Credit_Card_Numbers_Unsafe_Practices.pdf > > The paper mentions several techniques as well as rainbow tables. I am looking for anyone that has actually generated tables specifically geared toward this attack or for anyone that can offer configuration tips for JtR. Helping John make more efficient guesses would be the key, implementing logic from the paper would be quite useful. > > Thanks > -KF > I forgot to mention that I have an on-line validator that will validate numbers based on MIIs, card number length and Luhn. The only validation step it does not do is IIN validation. I wrote it many years ago during PII discovery at VT. http://16s.us/numbers/ You can generate some random 16 char or 14 char numbers and paste them into the validation fields to give you an idea of how much you can reduce this space. Brad
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