[Opensim-dev] open sim UUID and Passwordhash
Frisby, Adam
adam at deepthink.com.au
Fri Oct 16 15:26:43 UTC 2009
Technically, the client only mandates the first MD5.
It is possible for us to consider SHA256(MD5() . ':' . salt) instead.
Adam
> -----Original Message-----
> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-
> bounces at lists.berlios.de] On Behalf Of Dr Scofield
> Sent: Friday, 16 October 2009 8:20 AM
> To: opensim-dev at lists.berlios.de
> Subject: Re: [Opensim-dev] open sim UUID and Passwordhash
>
>
> Alan M Webb wrote:
> >
> > If everyone is really concerned about security, then perhaps we
> should
> > stop using MD5?
>
> ;-) who's going to tell the LL clients that?
>
> cheers,
> DrS/dirk
>
>
> >
> > Best regards
> > Alan
> > -------------------
> > T.J. Watson Research Center, Hawthorne, NY
> > 1-914-784-7286
> > alan_webb at us.ibm.com
> >
> >
> > From: "Frisby, Adam" <adam at deepthink.com.au>
> > To: "opensim-dev at lists.berlios.de" <opensim-
> dev at lists.berlios.de>
> > Date: 10/16/2009 09:06 AM
> > Subject: Re: [Opensim-dev] open sim UUID and Passwordhash
> >
> >
> > ---------------------------------------------------------------------
> ---
> >
> >
> >
> > Just because other software may do it wrong does not mean it is
> secure.
> >
> > Drupal using a plain MD5 is alarming – since it allows for very quick
> > plain lookups in existing databases (no need to calculate the
> dictionary
> > + permuation with your fixed salt). Storing a custom salt for each
> user
> > is essential if you wish to make dictionary attacks significantly
> more
> > expensive. (Actually it also allows for plain collision attacks too.)
> >
> > Consider this case:
> > · Calculate Every Permutation of the Dictionary plus a couple
> of
> > common modifications, plus your fixed salt. (this will get ~80%+ of
> user
> > passwords).
> > Versus
> > · Do the above, but for each user – since the salt is
> changing
> > per user.
> >
> > The second will take ‘n’ times longer to calculate (where N is
> > equivalent to the size of your database), it also works in the
> inverse –
> > if you have a 10 million user database, it means you need
> 1/10millionth
> > of the time to try calculate a valid hit. It adds up. Bigtime.
> >
> > A unique hash for the whole application helps against global world-
> wide
> > MD5 databases, but it still does not help the above situation.
> >
> > Frankly the storage and transmission size arguments are complete
> bunk.
> > We are talking 128-bits extra data per user for a good salt which
> adds
> > up to about ‘jack shit’ when summed over the lifetime of the
> > application. It takes very little extra time, and we already stuff
> that
> > data into our default database schemas.
> >
> > Likewise, having a long salt versus a short salt makes very little
> > difference – because it’s the uniqueness that counts (see the two
> cases
> > above.)
> >
> > Short summary of the above: Do it if you have any desire to follow
> good
> > security practices with your users. It takes almost no extra time and
> > gives you appreciable benefits.
> >
> > Adam
> >
> > *From:* opensim-dev-bounces at lists.berlios.de
> > [mailto:opensim-dev-bounces at lists.berlios.de] *On Behalf Of *Impalah
> > Shenzhou*
> > Sent:* Friday, 16 October 2009 4:37 AM*
> > To:* opensim-dev at lists.berlios.de*
> > Subject:* Re: [Opensim-dev] open sim UUID and Passwordhash
> >
> > Thanks for the info Melanie.
> >
> > Adam, I consider Drupal, for example, a CMS with a decent security
> and
> > it only uses md5(plain_password) to store user passwords. Some php
> > frameworks (for example Code Igniter, Cake php...) use, but not
> > mandatory, an unique hash for all the application.
> >
> > A random hash for every user improves security, you're right, but
> > increases the data sent between DB and servers for every
> authentication.
> > I prefer not to overload data transmission for something I think is
> > overprotection. Maybe for 10 or 100 users there won't be no problems,
> > but think on 10000 and each byte will count (they aren't cheap).
> >
> > If you have a long, secret and unique hash for your servers, who can
> > make an effective attack to you (at least in reasonable time)?
> >
> > Maybe the difference could be that Drupal used to be deployed over
> > Apache, and it can be protected against dictionary attacks activating
> > some modules, while Opensim/UGAIM are servers "per se", basic
> servers.
> >
> > It's my opinion, if you don't like it, I have more :-P
> >
> > Greetings
> >
> > 2009/10/16 Frisby, Adam <_adam at deepthink.com.au_
> > <mailto:adam at deepthink.com.au>>
> > A long fixed salt doesn’t help over the simple “:” in any practical
> way.
> > The salt *must* be unique for each user for decent security.
> >
> > Adam
> >
> > *From:* _opensim-dev-bounces at lists.berlios.de_
> > <mailto:opensim-dev-bounces at lists.berlios.de>
> > [mailto:_opensim-dev-bounces at lists.berlios.de_
> > <mailto:opensim-dev-bounces at lists.berlios.de>] *On Behalf Of *Impalah
> > Shenzhou*
> > Sent:* Friday, 16 October 2009 3:44 AM
> > *
> > To:* _opensim-dev at lists.berlios.de_ <mailto:opensim-
> dev at lists.berlios.de>*
> > Subject:* Re: [Opensim-dev] open sim UUID and Passwordhash
> >
> > This comes from UserManagerBase.AddUser (0.6.6):
> >
> > string md5PasswdHash = Util.Md5Hash(Util.Md5Hash(password) + ":" +
> > String.Empty);
> >
> > The salt should be where String.Empty is.
> >
> > I think it doesn't change in the most recent versions, so the "create
> > user" method of the console (both standalone and ugaim) are unsecure
> by
> > default.
> >
> >
> > Anyway, I agree with Melanie and Adam that the salt is needed for
> > improving security, if not a random salt every time you create an
> user,
> > at least a long and secret unique salt.
> >
> > Greetings
> >
> > 2009/10/16 Frisby, Adam <_adam at deepthink.com.au_
> > <mailto:adam at deepthink.com.au>>
> > +1 to Melanie, that code is *not* secure. It is salted with a ":" but
> > that's a fixed known salt.
> >
> > This is what I suggest:
> >
> > $passwordSalt = md5(time() . utime() . mt_rand(0,mt_getrandmax()));
> //
> > or any other good random source
> > $passwordHash = md5(md5($password) . ':' . $passwordSalt);
> >
> > $passwordSalt should be unique among your database (very likely with
> the
> > above code); if there are duplicates, then it allows dictionary
> attacks
> > to be done, the more duplicates, the more effective it is.
> >
> > Adam
> >
> >> -----Original Message-----
> >> From: _opensim-dev-bounces at lists.berlios.de_
> > <mailto:opensim-dev-bounces at lists.berlios.de> [mailto:_opensim-dev-_
> > <mailto:opensim-dev->
> >> _bounces at lists.berlios.de_ <mailto:bounces at lists.berlios.de>] On
> > Behalf Of Melanie
> >> Sent: Thursday, 15 October 2009 4:14 PM
> >> To: _opensim-dev at lists.berlios.de_ <mailto:opensim-
> dev at lists.berlios.de>
> >> Subject: Re: [Opensim-dev] open sim UUID and Passwordhash
> >>
> >> Please don't use that code. It creates unsalted hashes, which are
> >> not secure.
> >> The "" should be a ranndom salt, stored in the passwordSalt field in
> >> the DB. If that is blank, you're running a very insecure system
> >>
> >>
> >> Melanie
> >>
> >>
> >> Rich White wrote:
> >> > here is the PHP code - $password_hash = md5(md5($password) . ":"
> >> ."");
> >> >
> >> > an md5 hash of an md5 hash
> >> >
> >> > =====
> >> >
> >> > 2009/10/15 Márcio Cardoso <_marciomaiden at gmail.com_
> > <mailto:marciomaiden at gmail.com>>:
> >> >> Good night,
> >> >>
> >> >> will be possible that someone could help me with 2 problems I
> have?
> >> I'm
> >> >> trying to create a stored procedure in mysql to add users, but do
> >> not know
> >> >> how UUID is generated. anyone have any idea how this happens?
> >> Another
> >> >> problem is how is the encoding of the password.
> >> >>
> >> >> The ideal was to have access to the code that opensim uses to
> add
> >> avatars.
> >> >> but I got tired of looking and nothing. I thank you for your
> help.
> >> >>
> >> >> Greetings,
> >> >>
> >> >> Márcio Cardoso
> >> >>
> >> >> _______________________________________________
> >> >> Opensim-dev mailing list
> >> >> _Opensim-dev at lists.berlios.de_ <mailto:Opensim-
> dev at lists.berlios.de>
> >> >> _https://lists.berlios.de/mailman/listinfo/opensim-dev_
> >> >>
> >> >>
> >> > _______________________________________________
> >> > Opensim-dev mailing list
> >> > _Opensim-dev at lists.berlios.de_ <mailto:Opensim-
> dev at lists.berlios.de>
> >> > _https://lists.berlios.de/mailman/listinfo/opensim-dev_
> >>
> >> _______________________________________________
> >> Opensim-dev mailing list
> >> _Opensim-dev at lists.berlios.de_ <mailto:Opensim-dev at lists.berlios.de>
> >> _https://lists.berlios.de/mailman/listinfo/opensim-dev_
> > _______________________________________________
> > Opensim-dev mailing list_
> > __Opensim-dev at lists.berlios.de_ <mailto:Opensim-
> dev at lists.berlios.de>_
> > __https://lists.berlios.de/mailman/listinfo/opensim-dev_
> >
> >
> > _______________________________________________
> > Opensim-dev mailing list_
> > __Opensim-dev at lists.berlios.de_ <mailto:Opensim-
> dev at lists.berlios.de>_
> > __https://lists.berlios.de/mailman/listinfo/opensim-dev_
> > _______________________________________________
> > Opensim-dev mailing list
> > Opensim-dev at lists.berlios.de
> > https://lists.berlios.de/mailman/listinfo/opensim-dev
> >
> >
> >
> > ---------------------------------------------------------------------
> ---
> >
> > _______________________________________________
> > Opensim-dev mailing list
> > Opensim-dev at lists.berlios.de
> > https://lists.berlios.de/mailman/listinfo/opensim-dev
>
>
> --
> dr dirk husemann ---- virtual worlds research ---- ibm zurich research
> lab
> SL: dr scofield ---- drscofield at xyzzyxyzzy.net ----
> http://xyzzyxyzzy.net/
> RL: hud at zurich.ibm.com - +41 44 724 8573 -
> http://www.zurich.ibm.com/~hud/
> _______________________________________________
> Opensim-dev mailing list
> Opensim-dev at lists.berlios.de
> https://lists.berlios.de/mailman/listinfo/opensim-dev
More information about the Opensim-dev
mailing list