Re: [Full-disclosure] Re: choice-point screw-up and secure hashes
Date: 03/19/05

  • Next message: Jason Coombs: "Re: [Full-disclosure] Re: choice-point screw-up and secure hashes"
    To: Atom Smasher <>
    Date: Sat, 19 Mar 2005 17:38:09 -0500

    On Sat, 19 Mar 2005 13:34:53 EST, Atom Smasher said:

    > tell ya what... here's my SSN hashed with a salt:
    > =09e36c98b34d5ba979fb0bf0c64dc7b3a66c9ce841437d6460390e6380810f1440
    > as soon as you recover my SSN, just let me know.

    Tell you what - give me the salt and the hash algorithm, and it will be
    quick work indeed.

    Remember that the company probably needs an *invertible* function as they need to
    be able to access the original value, so the trick of "hash the SSN and see if
    you get the same to compare for equality" isn't usable. You can use a one-way
    function if the only question is "Is 109-00-4368 the SSN for Customer XYZ?". If
    you need to be able to answer "What is Customer XYZ's SSN?" you need an invertible
    function. And if you ever do a database JOIN based on SSN, you need the SSN.

    And the sad fact is that if the company's servers are compromised sufficiently
    to recover the hashed SSN, they're almost certainly compromised sufficiently to
    allow the theft of the software that handles the forward and reverse hashing.
    So considering the salt and the algorithm secure if the hash has been compromised
    is probably a bad idea..



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  • Next message: Jason Coombs: "Re: [Full-disclosure] Re: choice-point screw-up and secure hashes"

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