phc-discussions - Re: [PHC] "Attack on the iterative compression function"

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Message-ID: <20150419014559.GA4765@openwall.com>
Date: Sun, 19 Apr 2015 04:45:59 +0300
From: Solar Designer <solar@...nwall.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] "Attack on the iterative compression function"

Dmitry,

On Fri, Apr 17, 2015 at 10:55:31AM +0200, Dmitry Khovratovich wrote:
> In order to get the numbers for other values of t, you just change the
> constant 1.33 in main() to the number of passes.

This worked fine for the change to 4.0/3.0, but when I put 5.0/3.0, I
get an extra line of output:

Average Penalty for fraction 1 (100 close values): 1.33  Latency: 1.33 Read: 1.33

Since this line shows penalties of 1.33 rather than 1.00, I am concerned
that other reported penalties might be off as well.

Perhaps something else needs to be changed?

Can you explain the WIDTH_TEST / (3 * q) on this line? -

                        tradeoffs.push_back(TradeoffFunc(q, WIDTH_TEST / (3 * q),passes));

It corresponds to "unsigned top_size", and I don't see why e.g. for q=2
it should be WIDTH_TEST/6.

Thanks,

Alexander