john-users - try all repeated characters

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Message-ID: <20100801214455.GA24286@openwall.com>
Date: Mon, 2 Aug 2010 01:44:55 +0400
From: Solar Designer <solar@...nwall.com>
To: john-users@...ts.openwall.com
Subject: try all repeated characters

Hi,

Here's a contest-inspired external mode.  Due to the "small charset"
(just one character at a time), this can go to very high lengths yet
produce only a small number of candidate passwords.  Many "wordlists"
already have entries like this, though.

When applied to the contest hashes, this cracks two passwords:
"|||||||||" (for a {SSHA} hash) and "444444" (for a FreeBSD MD5 hash).

[List.External:Repeats]
int minlength, maxlength, minc, maxc, length, c;

void init()
{
	minlength = 1;
	maxlength = 72;
	minc = 0x20;
	maxc = 0xff;

	length = minlength; c = minc;
}

void generate()
{
	int i;

	i = 0;
	while (i < length)
		word[i++] = c;
	word[i] = 0;

	if (c++ < maxc)
		return;

	c = minc;
	if (++length > maxlength)
		c = 0; // Will NUL out the next "word" and thus terminate
}

Alexander

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