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apg – generates several random passwords


apg [-a algorithm] [-M mode] [-E char_string] [-n num_of_pass] [-m
min_pass_len] [-x max_pass_len] [-r dictfile] [-b filter_file] [-p
min_substr_len] [-s] [-c cl_seed] [-d] [-y] [-l] [-t] [-q] [-h] [-v]


apg generates several random passwords. It uses several password gener‐
ation algorithms (currently two) and a built-in pseudo random number

Default algorithm is pronounceable password generation algorithm
designed by Morrie Gasser and described in A Random Word Generator For
Pronounceable Passwords National Technical Information Service (NTIS)
AD-A-017676. The original paper is very old and had never been put
online, so I have to use NIST implementation described in FIPS-181.

Another algorithm is simple random character generation algorithm, but
it uses four user-defined symbol sets to produce random password. It
means that user can choose type of symbols that should appear in pass‐
word. Symbol sets are: numeric symbol set (0,…,9) , capital letters
symbol set (A,…,Z) , small letters symbol set (a,…,z) and special
symbols symbol set (#,@,!,…).

Built-in pseudo random number generator is an implementation of algo‐
rithm described in Appendix C of ANSI X9.17 or RFC1750 with exception
that it uses CAST or SHA-1 instead of Triple DES. It uses local time
with precision of microseconds (see gettimeofday(2)) and /dev/random
(if available) to produce initial random seed.

apg also have the ability to check generated password quality using
dictionary. You can use this ability if you specify command-line
options -r dictfile or -b filtername where dictfile is the dictionary
file name and filtername is the name of Bloom filter file. In that dic‐
tionary 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. Bloom filter file should be created with apgbfm utility
included in apg distribution. In future releases I plan to implement
some other techniques to check passwords (like pattern check) just to
make life easier.


Password generation modes options
-a algorithm
use algorithm for password generation.
0 – (default) pronounceable password generation
1 – random character password generation

-n num_of_pass
generate num_of_pass number of passwords. Default is 6.

-m min_pass_len
generate password with minimum length min_pass_len. If
min_pass_len > max_pass_len then max_pass_len = min_pass_len.
Default minimum password length is 8.

-x max_pass_len
generate password with maximum length max_pass_len. If
min_pass_len > max_pass_len then max_pass_len = min_pass_len.
Default maximum password length is 10.

-M mode
Use symbolsets specified with mode for password generation.
mode is a text string consisting of characters S, s, N, n, C, c,
L, l. Where:

S generator must use special symbol set for every generated

s generator should use special symbol set for password gen‐

N generator must use numeral symbol set for every generated

n generator should use numeral symbol set for password gen‐

C generator must use capital symbol set for every generated

c generator should use capital symbol set for password gen‐

L generator must use small letters symbol set for every
generated password (always present if pronounceable pass‐
word generation algorithm is used).

l generator should use small letters symbol set for pass‐
word generation.

R,r not supported any more. Use -E char_string option
mode can not be more than 4 characters in length.

Usage of L, M, N, C will slow down password generation process.

-M sncl or -M SNCL or -M Cn

-E char_string
exclude characters in char_string from password generation
process (in pronounceable password generation mode you can not
exclude small letters). To include special symbols that can be
recognized by shell (apostrophe, quotes, dollar sign, etc.) in
char_string use the backslashed versions.


Command apg -a 1 -M n -n 3 -m 8 -E 23456789 will generate a set
of passwords that will look like this

Command apg -a 1 -M nc -n 3 -m 26 -E GHIJKLMNOPQRSTUVWXYZ will
generate a set of passwords that will look like this

Password quality control options
-r dictfile
check generated passwords for their appearance in dictfile

-b filter_file
check generated passwords for their appearance in filter_file.
filter_file should be created with apgbfm utility.

-p min_substr_len
this option tells apg to check every substring of the gener‐
ated password for appearance in filter_file. If any of such sub‐
strings would be found in the filter_file then generated pass‐
word would be rejected and apg will generate another one.
min_substr_len specifies minimum substring length to check.
This option is active only if -b option is defined.

Pseudo random number generator options
-s ask user for random sequence for password generation

-c cl_seed
use cl_seed as a random seed for password generation. I use it
when i have to generate passwords in a shell script.

Password output options
-d do NOT use any delimiters between generated passwords. I use it
when i have to generate passwords in a shell script.

-y print generated passwords and crypted passwords (see man

-q quiet mode (do not print warnings)

-l spell genetated passwords. Useful when you want to read gener‐
ated password by telephone.
WARNING: Think twice before read your password by phone.

-t print pronunciation for generated pronounceable password

-h print help information and exit

-v print version information and exit



apg -a 0 -M sncl -n 6 -x 10 -m 8 (new style)

If you want to generate really secure passwords, you should use option
-s. To simplify apg usage, you can write a small shell script. For
[begin]—-> pwgen.sh
/usr/local/bin/apg -m 8 -x 12 -s
[ end ]—-> pwgen.sh

On successful completion of its task, apg will complete with exit code
0. An exit code of -1 indicates an error occurred. Textual errors are
written to the standard error stream.

If /dev/random is not available, apg will display a message about it.



None. If you’ve found one, please send bug description to the author.




Adel I. Mirzazhanov,
Project home page: http://www.adel.nursat.kz/apg/

Automated Password Generator 2003 Aug 04 APG(1)