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Date: Sun, 12 May 2019 23:25:14 +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:
> Duplicate character 3 times for every position, for positions 0-35:
[...]
> 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
Minor mistake in this rule: there is 1 position overlap between internal
packs (e.g. 0+V vs V+0), but sequential dupe suppression hides it, so
there are no dupes during hashing.
So the rule should be the following:
--rules=': vc0V vccV vd0c vccV vc0c vb0[0Vdc] va[0-9A-U]b >a Xa1a Xa1a'
The change is 'U' in 'va[0-9A-U]b'.
It covers positions 0-123.
To debug manipulations on variables, I used the following command:
$ python -c "print '_' * 125" | john 2>/dev/null --pipe --stdout \
--rules=': ... oaA' \
| perl -pe 's/^(_*)A_*$/length $1/e'
Positions 0-30: va[0-9A-U]0
Positions 31-61: vb0V va[0-9A-U]b
Merge the ranges using preprocessor:
Positions 0-61: vb0[0V] va[0-9A-U]b
Positions 62-92: vc0V vccV vd0c vb0d va[0-9A-U]b
Positions 0-92: vc0V vccV vd0c vb0[0Vd] va[0-9A-U]b
Positions 93-123: vc0V vccV vd0c vccV vc0c vb0c va[0-9A-U]b
Positions 0-123: vc0V vccV vd0c vccV vc0c vb0[0Vdc] va[0-9A-U]b
So there are base values 0, 31, 62 and 93. All base values are computed
in every rule (after preprocessing), but only one value is used. Then
0-30 is added.
Lack of gaps may be checked with the following additional command in the
pipe:
... | perl -ne 'print "failure\n" if $. != $_ + 1'
Thanks!
--
Regards,
Aleksey Cherepanov
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