phc-discussions - Re: [PHC] The SkinnyCat lives

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAAyV7nG8c4y2GnZ78HSnE5LhHd5pQJ0xj+2YrsH4vbRp8Kh=fQ@mail.gmail.com>
Date: Wed, 26 Mar 2014 11:58:51 -0400
From: Anthony Ferrara <ircmaxell@...il.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] The SkinnyCat lives

Bill,

I opened a quick issue. It appears that SkinnyCat limits passwords to 255
bytes due to the length parameter being declared as a `uint8_t`. The
algorithm itself seems to support longer passwords as everywhere else it is
used internally other than the 2 function headers is represented by a
`unit32_t` field. So not sure if this is intentional or not, nor if it is
an issue or not. Just pointing out an observation.

Anthony


On Wed, Mar 26, 2014 at 8:40 AM, Bill Cox <waywardgeek@...il.com> wrote:

> In case anyone's interested, I've checked in a reference
> implementation of "SkinnyCat", a stripped-down version of TwoCats.
> It's in the skinnycat subdirectory of twocats, which as always, is at:
>
>     https://github.com/waywardgeek/twocats
>
> It came out nicer than I thought it would.  The purpose of SkinnyCat
> is to be simple to implement while providing "good-enough" memory-hard
> password security for applications that need a simpler PHS than
> TwoCats.
>
> Basically, it still hashes memory in two loops, the first one being
> resistant to cache-timing attacks, and the second loop being
> unpredictable to increase defense against brute force guessing
> attacks.  It results in a 256 bit hash, and works currently with
> Blake2s and SHA256.  It's a bit over 200 lines of code.  It takes only
> one cost parameter: memCost, which causes it to hash 1KiB * 2^memCost.
>  The reference implementation hashes 2GiB in 0.451 seconds on my
> 3.4GHz Ivy Bridge Core i7, using 1 thread.  It does 16MiB in 4ms.
> There's room for some speed improvement with SSE/AVX2 optimization,
> but I'm not planning on complicating this little project that way.
> TwoCats on one thread does 2GiB of SkinnyCat hashing in 0.425 seconds,
> with SSE2 optimization.
>
> The reference TwoCats main.c wrapper implements a SkinnyCat interface
> with the -a skinnycat flag, and I've verified it generates the same
> hashes for memCost up to 21.
>
> I'm still working on updating the documentation to include SkinnyCat,
> but the code should be pretty clear.
>
> Bill
>

Content of type "text/html" skipped