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Date: Thu, 23 Apr 2015 22:45:26 +0800
From: Kai Zhao <>
Subject: Re: Advice on proposal: John the Ripper jumbo robustness

> Let's see where the next bottleneck is.

I have tried 3 days to find the next bottleneck. There are two ways I have
tried, both the two ways speed up a little which is about dozens of

1. Remove the useless source code to make the size of john smaller

2. Remove the useless functions in john.c

Finally, I found that the key of fuzz the valid() function is this line:

ldr_load_pw_file(&database, current->data);

We init the john by registering fmts, reading configs, and so on, after the
init done, we run the ldr_load_pw_file() function which will valid the hash.
It takes some time from the start of john to the function
And we repeat it in every case, thus it wastes a lot of time.

I think it is a better way that we init only once and use fork to copy the
progress to child. The child only needs to run the ldr_load_pw_file().

AFL has come up this idea with 'The fork server', more details below:

I think we should custom AFL to init only once. Do you agree with this idea?



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