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Date: Sun, 12 May 2019 22:36:35 +0300
From: Aleksey Cherepanov <lyosha@...nwall.com>
To: john-users@...ts.openwall.com
Subject: Re: team john-users write-up for CracktheCon contest at CypherCon 2019

Aleksey Cherepanov <lyosha@...nwall.com> writes:
> The efficiency of pattern decreases through rockyou.txt, so you would
> need to use --rules-stack option instead of --rules, and abort session
> when it is inefficient:
> $ john --wordlist=rockyou.txt --rules-stack=': i[3-7][&\-.+]' ...
[...]
> - Duplicate the last character 3-5 times:
> $ john --wordlist=rockyou.txt --rules=': Z[3-5]' ...

Ouch, there should be --rules-stack option too:
$ john --wordlist=rockyou.txt --rules-stack=': Z[3-5]' ...


Originally the rule was written differently and started in 3 separate
sessions:
$ john --wordlist=rockyou.txt --rules=': val1 Xa1z Xa1z Xa1z' ...
$ john --wordlist=rockyou.txt --rules=': val1 Xa1z Xa1z Xa1z Xa1z' ...
$ john --wordlist=rockyou.txt --rules=': val1 Xa1z Xa1z Xa1z Xa1z Xa1z' ...

While 'Z' is the shortest possible rule for the job, other variants are
possible too. Instead of 'val1' and 'Xa1z', it is possible to use 'Xm1z'
with special variable 'm'. OTOH user-defined variable allows to make
customizable rule to duplicate character at given position easily with
'Xa1a' (notice 'a' instead of 'z' on the end).

Duplicate character 3 times for every position, for positions 0-35:
$ echo ABCD | john --pipe --stdout 2>/dev/null \
  --rules=': va[0-9A-Z]0 >a Xa1a Xa1a Xa1a'
AAAABCD
ABBBBCD
ABCCCCD
ABCDDDD

Just to demonstrate endless possibilities of rules, there is the same
rule for positions 0-124, i.e. up to max length (but position 124 is not
meaningful for duplication):
$ echo 123 | john --pipe --stdout 2>/dev/null \
  --rules=': vc0V vccV vd0c vccV vc0c vb0[0Vdc] va[0-9A-V]b >a Xa1a Xa1a'
11123
12223
12333

It was not tried against the hashes though. I have to go... :-)

Thanks!

--
Regards,
Aleksey Cherepanov

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