phc-discussions - Re: [PHC] Another PHC candidates "mechanical" tests

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Date: Tue, 11 Nov 2014 10:00:21 +0100
From: Krisztián Pintér <pinterkr@...il.com>
To: "discussions@...sword-hashing.net" <discussions@...sword-hashing.net>
Subject: Re: [PHC] Another PHC candidates "mechanical" tests

On Mon, Nov 10, 2014 at 7:50 PM, Milan Broz <gmazyland@...il.com> wrote:
> (It printed a lot of assert messages about supported parameters,
> not much user friendly and I did not study it in detail.

i know it is highly off topic here, but can't resist. i don't think
that such low level functions should do any more error reporting. if
you call them with wrong parameters, the situation is unrecoverable,
an exception or an error code won't help it. on the contrary, it just
makes the system that much more vulnerable. (consider attacker somehow
corrupt the parameters, causing the caller to skip encryption or
hashing altogether, or dump sensitive information to unsafe places,
due to a bug in the error handling. we've seen this before.)

if i was rewriting my code, i would probably move the memory
allocation out of the core function as well.
reason 1: the complexity of a heap memory allocation is way greater
than the complexity of the hash itself. good bye KISS design!
reason 2: the caller might want some control over the allocation of
memory. like it wants to skip the heap manager, and allocate memory
directly from the OS.
the correct way is to take a pointer to the memory block to use. it
might also help zeroing the array (lessen the risk of the compiler
optimizing the zeroing away).