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Date:      Tue, 06 Mar 2001 11:10:03 +1100
From:      Tony Landells <ahl@austclear.com.au>
To:        Bill Moran <wmoran@iowna.com>
Cc:        Mikko Tyolajarvi <mikko@dynas.se>, questions@FreeBSD.ORG
Subject:   Re: SUN TO BSD 
Message-ID:  <200103060010.LAA00329@tungsten.austclear.com.au>
In-Reply-To: Message from Bill Moran <wmoran@iowna.com>  of "Mon, 05 Mar 2001 18:50:40 CDT." <3AA4264F.7AF4B2A5@iowna.com> 

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The traditional UNIX password encryption takes a timestamp of when
the password is set, and uses that as the "salt" (or seed) for the
initial encryption.  It then adds this salt to the encrypted string
so it can be retrieved next time you want to check the password.

This means that even if two users pick the same password it should
look different because it was done at a different time.

By default FreeBSD uses MD5 for password encryption.  Since this
is a completely different algorithm, the encrypted string bears
nothing more than a passing similarity to "traditionally" (DES)
encrypted strings.

You have the option of getting FreeBSD to use DES encrypted passwords.
If you do that, you can just cut and paste the password field from
/etc/shadow on Solaris into /etc/master.password on FreeBSD.

Most UNIX systems use DES for passwords.  I don't know why FreeBSD
switched to MD5--possibly a lack of trust in DES, possibly because
of stupid export laws.  I'm sure someone else on the list will provide
a definitive answer.

Cheers,
Tony

Bill Moran wrote:
> Mikko Tyolajarvi wrote:
> > 
> > In local.freebsd.questions you write:
> > >I believe this has to do with the system default password encryption
> > >scheme. If both your Solaris & FreeBSD boxes are using the same
> > >encryption scheme you should see the same encryped password. I've seen
> > 
> > Nope.  Password encryption schemes adds a "salt" (12 bits for the
> > traditional DES version) to try to avoid passwords encrypting to the
> > same value -- otherwise dictionary attacks become a lot simpler.
> 
> Straighten me out on this, then. (if you'd be so kind)
> Do all systems use different password math? If so, how does FreeBSD
> share it's data with Solaris, Linux, et al via NIS? It couldn't be
> sending the passwords in cleartext, because they're not decryptable
> (right?) That would be insane anyway.
> 
> I thought you had the option of using DES or MD5 for the password
> storage?
> 
> Am I a little off in my understanding of this?
-- 
Tony Landells					<ahl@austclear.com.au>
Senior Network Engineer				Ph:  +61 3 9677 9319
Australian Clearing Services Pty Ltd		Fax: +61 3 9677 9355
Level 4, Rialto North Tower
525 Collins Street
Melbourne VIC 3000
Australia



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