NAME
apgbfm - APG Bloom filter management program
SYNOPSIS
apgbfm -f filter -n numofwords [-q] [-s]
apgbfm -f filter -d dictfile [-q] [-s]
apgbfm -f filter -a word [-q]
apgbfm -f filter -A dictfile [-q]
apgbfm -f filter -c word [-q]
apgbfm -f filter -C dictfile [-q]
apgbfm -i filter
apgbfm [-v] [-h]
DESCRIPTION
apgbfm is used to manage Bloom filter that is used to restrict password
generation in APG pasword generation software. Usage of the Bloom
filter allows to speed up password check for large dictionaries and has
some other benefits.
The idea to use Bloom filter for that purpose is came from the
description of the OPUS project OPUS: Preventing Weak Password Choices
Purdue Technical Report CSD-TR 92-028 writen by Eugene H. Spafford.
You can obtain this article from:
http://www.cerias.purdue.edu/homes/spaf/tech-reps/9128.ps
It has very nice description of Bloom filter and it’s advantages for
password checking systems.
In simple words, apgbfm generates n hash values for every word and sets
corresponding bits in filter file to 1. To check the word apgbfm
generates the same hash functions for that word and if all n
corresponding bits in filter file are set to 1 then it suppose that
word exists in dicionary. apgbfm uses SHA-1 as a hash function.
apgbfm can be used as standalone utility, not only with apg, or apgd.
WARNING !!!
Filter file format can be changed in the future. I’ll try to
make file formats compatible but i can not guaranty this.
WARNING !!!
apgbfm may slow down your computer during filter creation.
OPTIONS
-f filter
use filter as the name for Bloom filter filename.
-i filter
print information about filter.
-n numofwords
create new empty filter for numofwords number of words. Useful
when you want to fill filter dynamicaly.
-d dictfile
create new filter from dictfile. It may take a lot of time to
generate filter from a big dictionary. In that dictionary you
may place words (one per line) that should not appear as
generated passwords. For example: user names common words, etc.
You even can use one of the dictionaries that come with
dictionary password crackers. This check is case sensitive. For
example, if you want to reject word ’root’, you should insert in
dictfile words: root, Root, RoOt, ... , ROOT. To indicate that
program is working apgbfm prints dot for every 100 words added
in dictionary.
-a word
add word to the filter.
-A dictfile
add all words from dictfile to the filter. To indicate that
program is working apgbfm prints dot for every 100 words added
in dictionary.
-c word
check word for appearance in the filter.
-C dictfile
check every word from dictfile for appearance in the filter.
-q quiet mode.
-s create new filter in case-insensitive mode.
-v print version information.
-h print help information.
EXIT CODE
On successful completion of its task, apgbfm will complete with exit
code 0. An exit code of -1 indicates an error occurred. Textual
errors are written to the standard error stream.
FILES
None.
BUGS
None. If you’ve found one, please send bug description to the author.
This man page is Alpha too.
SEE ALSO
apg(1)
AUTHOR
Adel I. Mirzazhanov, <a-del@iname.com>
Project home page: http://www.adel.nursat.kz/apg/