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Date: Mon, 19 May 2014 09:10:42 +0400
From: Dennis Schridde <devurandom@....net>
To: john-users@...ts.openwall.com
Subject: Partially known PGP key password

Hello everyone!

A friend of mine only remembers the beginning of his PGP key password
and needs to recover the rest. I suggested John and already converted
the key using gpg2john and created a john.local.conf similar to the
following:

[List.Rules:R]
Az~[a]
Az~[a][b]
Az~[a][b][c]

where a,b,c are possible characters of the password. Now I am running
John with a wordlist that contains only one line: The known first
characters.

My question is: Is this an efficient way to crack the password? (My
machine has two cores, but John compiled with OpenMP only uses one,
while I would assume the task to be easily parallelisable.)

When I talked to Magnum (actual question below [1]), he pointed out that
I might be using too many salts. Now Johns says "Loaded 2 password
hashes with 2 different salts (OpenPGP / GnuPG Secret Key [32/64])", so
I assume that two are not really too many, right? And it seems those
salts came from the PGP key itself, because the file gpg2john created
contains two lines, and I do not see any other resemblance of the
number "2" anywhere.

Best regards,
Dennis

[1]
> I read that I can make john output a status line by pressing <space>
> during runtime. I also read that I can execute john -status from
> another console and it will examine the john.rec file to print the
> status line there. However, neither method works on my system:
>
> Pressing space just does nothing. Pressing q sometimes exits john
> immediately, but I cannot reproduce that now. Pressing ^C results in a
> line "Wait...", but nothing happens. Pressing ^C aborts the session
> immediately.
>
> Executing john -status results in the message that the file john.rec
> does not exist.

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