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Message-ID: <4EEE4056.7000704@gmail.com>
Date: Sun, 18 Dec 2011 14:34:46 -0500
From: Jordan Bradley <jordan.w.bradley@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: Making a thread safe implementation of bitslice DES
On 11-12-18 02:17 PM, Solar Designer wrote:
> On Sun, Dec 18, 2011 at 01:54:34PM -0500, Jordan Bradley wrote:
>> I'm writing a multithreaded application (using pthreads) using OpenSSL's
>> DES_fcrypt function which does the job but is slow.
> What are you doing this for?
I'm writing a distributed tripcode cracking program.
>> I'd like to use
>> JTR's bitslice implementation but it doesn't seem to be thread safe.
> It is thread-safe (in 1.7.9) as long as each thread uses its own
> instance of a DES_bs_combined structure. This is what happens when
> 1.7.9 is built with OpenMP support, but you may as well use this with
> explicit pthreads if you like.
>
> Thread-safety generally has some performance cost, though. This is why
> when 1.7.9 is built without OpenMP support, it simply uses a static
> instance of a DES_bs_combined structure, called DES_bs_all. This avoids
> the need for some pointer indirection.
>
> There's also a DES_bs_all with OpenMP-enabled builds, but there
> DES_bs_all is a C preprocessor macro that uses the global DES_bs_all_p
> pointer and the local variable "t". In your code, you may do it
> similarly or differently.
>
>> In the end I'd like it to be a drop-in replacement of DES_fcrypt()
> This is impossible. The whole point of doing a bitslice implementation
> is that it will process multiple inputs in parallel and produce multiple
> outputs. This doesn't fit in the DES_fcrypt() interface.
>
> Also, crypt(3) and DES_fcrypt() have some overhead to convert the ASCII
> salt string to binary, to perform DES final permutation, and to encode
> the resulting DES block with base-64 characters. If you care about
> performance, you'll want to avoid this kind of overhead, which implies
> that you shouldn't use this interface.
>
> Alexander
Right now the method I use to generate passwords only uses printable
characters in the ASCII range excluding # and ', however I eventually
want to include japanese characters to increase keyspace.
Jordan
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