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Date: Wed, 30 Jan 2013 00:47:02 +0100
From: magnum <>
Subject: Re: Speeding up WPAPSK, by leveraging salt shortcomings

On 29 Jan, 2013, at 17:55 , jfoug <> wrote:
> So, in reality, we do have 10 unique salts.  However, during our call to crypt_all, we should only perform the 2 block PBKDF2(4096) one time.  However, the way JtR 'works', is it calls
> while (more_salts) {
>    set_salt(cur_salt++);
>    crypt_all()
>    cmp_all()
> }

Here's a beautyfully simple thought: If we could force John to serve the salts (the current code's salt structs) in essid order, so any same-essid salts would always be *consecutive*, we'd do fine with this one-line change to crypt_all:

+	if (new_keys || strcmp(last_essid, cur_salt->essid))
		for (i = just like current code)
			pbkdf2(just like current code)


Unless I'm confused now, this is all there is to it (except trivially introducing new_keys and last_essid). But how would we accomplish that prerequisite? We could have pcap2john sort its output, but would that guarantee John would use them in that order? Anyway this would be non-ideal - eg. if concatenating input files, they might become unsorted.


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