Take clean word from dictionary to build random pass phrase with fixed entropy
This pass phrase generator take clean words from dictionary to build random phrases and compute entropy.
Follow the idea found at: http://xkcd.com/936/
It is a perl script that take a
create a uniq cleaned words list (with only flat lower letters from
take randoms words and compute entropy.
Usage: passphrase.pl [-h] [-q] [-d dict file] [-s outputfile] [-i mIn length] [-a mAx length] [-e entropy bits] [-r random file] [-w words] [-l lines] [lines] Version: passphrase.pl v22.214.171.124 - (2013-07-05 08:51:52). -h This help. -l num number of phrases to generate (default: 1) -w num number of words by phrase (default: 5) -e bits Entropy bits for each words (default: 15) -d filename Dictionary file (default: /usr/share/dict/american-english) -s filename Dict file to save after initial drop (default: none) -i length Minimal word length (default: 4) -a length Maximal word length (default: 11) -r device Random file or generator (default: /dev/urandom) -q Quietly generate lines without computations.
$ ./passphrase.pl -l 4 With 5 words over 32768 ( 15 entropy bits ) = 1/3.777893e+22 -> 75 bits. With 5 words from 56947 ( 15.797 entropy bits ) = 1/5.988999e+23 -> 78.987 bits. 3.634 192.718 airfoils desolated babysitting hits digresses 3.391 173.916 acidic parents scary trespassed fascinate 3.704 164.515 occluded rarely sweatier metallic squat 3.907 192.718 available stockpiling blazoning jaywalk chino
Explanation: There are 56947 word (15.79bits) containing 4 to 11 letters in /usr/share/dict/american-english, after randomly dropped this down to 32768 (round to 15 bits entropy), building lines of 5 random words, compute shannon's entropy and flat entropy, for each lines and printout.
$ ./genpassphrase.pl -q firmly predeceased titanium slobbered betrayers