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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 generation algorithms
(currently two) and a built-in pseudo random number generator.

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 password. 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 algorithm 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 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. Bloom filter file should be
created with apgbfm(1) 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


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 password.

s generator should use special symbol set for password generation.

N generator must use numeral symbol set for every generated password.

n generator should use numeral symbol set for password generation.

C generator must use capital symbol set for every generated password.

c generator should use capital symbol set for password generation.

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

l generator should use small letters symbol set for password generation.

R,r not supported any more. Use -E char_string option instead.
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(1) utility.

-p min_substr_len
this option tells apg(1) to check every substring of the generated password for
appearance in filter_file. If any of such substrings would be found in the
filter_file then generated password would be rejected and apg(1) 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 crypt(3))

-q quiet mode (do not print warnings)

-l spell genetated passwords. Useful when you want to read generated password by
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 example:
[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.

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