Request for feedback: how slow is your slowest MAAS cloud?

[John Meinel]

I'll note that if you're generating a password, there really isn't a reason
to then pbkdf2 it, is there? I thought the reason to use pbkdf2 was because
it is too easy to generate SHA hashes for common *human* passwords. But as
the brute-force search spaces increases exponentially with more bits, just
generate longer passwords.

So if you are generating a random password, just make it 50 /dev/random
bytes long, and then you can use just simple 'sha' as the mapping back to a
password hash.

At least, my understanding is that scrypt/et al exist because Humans cannot
remember good passwords, so they get massaged into slightly better
passwords by lots of rounds. But if you just started with more entropy in
the password, you don't have to worry about that.

John
=:->


On Fri, Jun 2, 2017 at 6:59 AM, Seth Arnold <seth.arnold at canonical.com>
wrote:

> On Thu, Jun 01, 2017 at 05:46:52PM -0700, Mike Pontillo wrote:
> >    In doing so, I'm looking at deriving an shared key that can be used to
> > encrypt network traffic between peer rack and region controllers, and
> > eventually commissioned machines. The industry standard for key
> derivation
> > is the PBKDF2 algorithm, which makes brute force attacks to derive the
> > password from the key harder (by repeatedly running a hash function).
>
> PBKDF2 is also fairly old; I believe most cryptographers would prefer
> argon2, scrypt, or bcrypt to PBKDF2, with a grudging acceptance that if
> you have to sell into the FIPS marketplace you may not have a choice.
> Do we have a choice?
>
> We should also worry about the asymmetry of attackers vs defenders.
> Hashcat on gtx1080 GPUs can crack roughly a thousand of these
> million-iteration PBKDF2 per second.
>
> (I'm extrapolating a bit from the data easily available. This forum post
> says the benchmark uses 1000 iterations:
> https://hashcat.net/forum/thread-5799.html
> And these results say that it can run over a million per second:
> https://gist.github.com/epixoip/6ee29d5d626bd8dfe671a2d8f188b77b
> https://gist.github.com/epixoip/a83d38f412b4737e99bbef804a270c40
> So my assumption is one thousand times the work means a one thousand time
> slowdown. I haven't tested these speeds myself.)
>
> This points out that no matter how expensive the KDF being used,
> passwords such as '123456' 'monkey' etc are always terrible. It might
> take the controllers one second or so to generate the key, but given a
> password in the usual top-1000 list of passwords, hashcat can break it
> in about the same time it took to generate it.
>
> Thanks
>
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