IDS Forum

Re: HASH anyone?

Posted By: Jonathan Leffler
Date: Wednesday, 10 February 2010, at 7:55 p.m.

In Response To: Re: HASH anyone? (John Miller iii)

On Wed, Feb 10, 2010 at 08:22, John Miller iii <miller3@us.ibm.com> wrote:

> Can you please explain the difference between what you are asking
> and column level encryption.
>
> Mike Magie wrote on 02/10/2010 07:31:46 AM:
> > Oh and by hash I mean encyption hash, i.e. MD5 - not any other kind
> of hash.
>

The primary difference between a hash of a value and the result of
encrypting the same value is that the result of a hash is fully
deterministic (you will always get the same value) whereas the encrypted
column should be different every time (at least, for the first 2^56 or so
repetitions; after that, you might get a couple of values the same by virtue
of the Birthday Paradox).

It would be good to have cryptographic hashes built into IDS and exposed -
they are built-in in the cryptographic libraries (part of GSkit), but not
exposed.

We can debate whether MD5 should be used - it is not accepted for some
purposes because it is too easy to create different texts that hash to the
same result. However, were I doing it, I would provide MD5 (128 bits), and
SHA1 (160 bits), and the SHA-2 suite (SHA-256, SHA-384, SHA-512). NIST is
running a competition to determine a new SHA-3 suite, roughly like it did
with the AES encryption. When that is finalized (late next year, IIRC), I
would add that, too.

--
Jonathan Leffler #include <disclaimer.h>
Email: jleffler@earthlink.net, jleffler@us.ibm.com
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--000e0cd1389688527f047f489986

Messages In This Thread

• HASH anyone?
  MIKE MAGIE -- Tuesday, 9 February 2010, at 5:00 p.m.
  • Re: HASH anyone?
    MIKE MAGIE -- Wednesday, 10 February 2010, at 10:31 a.m.
    • Re: HASH anyone?
      John Miller iii -- Wednesday, 10 February 2010, at 11:22 a.m.
      • Re: HASH anyone?
        Art Kagel -- Wednesday, 10 February 2010, at 11:25 a.m.
      • Re: HASH anyone?
        Jonathan Leffler -- Wednesday, 10 February 2010, at 7:55 p.m.
      • Re: HASH anyone?
        MIKE MAGIE -- Thursday, 11 February 2010, at 10:13 a.m.

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