phc-discussions - Re: [PHC] Client-side hashing (was side-channel stuff)

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Message-Id: <004D53D5-8AEE-4EE7-B61D-029CCEC07BA3@codingrobots.com>
Date: Sat, 25 Apr 2015 17:35:58 +0200
From: Dmitry Chestnykh <dmitry@...ingrobots.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] Client-side hashing (was side-channel stuff)

> On 25 Apr 2015, at 15:46, Bill Cox <waywardgeek@...il.com> wrote:
> 
> yOn Sat, Apr 25, 2015 at 2:57 AM, Sascha Schmidt <sascha.schmidt@...-weimar.de <mailto:sascha.schmidt@...-weimar.de>> wrote:
> 2015-04-25 0:40 GMT+02:00 Steve Thomas <steve@...tu.com <mailto:steve@...tu.com>>:
> > h = fastHash(password, salt)
> > for u = 1 to upgrade
> > {
> >   h = fastHash(slowHash(h, t_cost, m_cost))
> >   t_cost = increaseTCost(t_cost)
> >   m_cost = increaseMCost(m_cost)
> > }
> > return encrypt(h, key) // HSM? :)
> You are totally right. I don't know how I missed this. The most
> embarrassing thing is, that this would already be possible with
> Catena. The only thing missing is the server-side finalization with
> encryption.
> I hope I haven't caused any confusion with my previous mail.
> 
> In this case, can everything but the last step be done client-side?  Ideally, the salt is a secret known only to the server and client, where the client preferably stores it in a security key of some sort.

Well, if a client can store a secret, we can ditch passwords altogether.

-- 
Dmitry Chestnykh
Coding Robots
http://www.codingrobots.com


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