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:
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
(8),
apg(1)
AUTHOR
Adel I. Mirzazhanov, <a-del@iname.com>
Project home page: http://www.adel.nursat.kz/apg/