Re: Values to use for a salt?

"Richard M. Conlan" <[email protected]>
Newsgroups gmane.comp.security.programming
Message-ID <[email protected]>
So, I think the problem here is that terminology is getting garbled.

If you just prepend 5__#$ to every password, and then treat the combined
string as the password, you have NOT used a salt. However, you have made
the password "more random" by ensuring, for instance, that none of the
passwords are in a standard Webster's dictionary. The problem is that this
is only a useful defense against a clueless attacker, since any decent
attacker would just update the dictionary to account for the prepended
5__#$.

Richard M. Conlan

>
>
>> Most systems that I'm aware of use the same key, I presume for speed
>> reasons.
>
> Or because they're written by people who don't know what
> they're doing.
>
>> Since the key is added to the password before hashing it seems to  me
>> that it only serves to make the password more random.  So "MyPassword"
>>  becomes "1234MyPassword".  This has only made the password more
>> random and  generates the same hash code for every password that is
>> "MyPassword".
>
> If you're going to salt, then you need to put the salt at the *END* of
> the password.  Otherwise the cracker can precompute the salt in the
> hashing routine, and there's no speed difference between a salted
> password and an unsalted password.
>
> 	SALTpassword	<== precompute hash of SALT, then do all
> 			    possible passwords.
>
> 	passwordSALT	<== compute each password followed by
> 			    salt - no precomputation possible.
>
> Always put the 'known' bit last.  (Here assuming the salt is
> either known (stored in the resulting hash) or knowable (it's
> stored somewhere inside the application or application logic
> and thus is essentially knowable anyway.)
>
>> Couldn't agree more and one benefit of using salt is that it creates
>> more  random passwords.
>
> I still have no idea what you really mean here.
>
> password+salt is not a password, it's a password+salt.
> It's the 'thing to be hashed' but it's not the password
> any more.
>
>
>
> --
> Brian Hatch                  Turning off setuid bits
>    Systems and                of important unix tools
>    Security Engineer          is like poking out an
> http://www.ifokr.org/bri/     eye to prevent misuse.
>                               -- Nick Esborn.
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