Quote from: EskimoBob on September 11, 2011, 10:15:18 AM

DO NOT USE WEBSITES TO GENERATE YOUR PASSWORDS

There is a good chance that your new and shiny password is stored for later attacks!

Create 4 random passwords which contains no special characters and are 10 characters long:

Code:

cat /dev/urandom| tr -dc 'a-zA-Z0-9' | fold -w 10| head -n 4

Create 4 random passwords which DO contains special characters and are 12 characters long:

Code:

$ cat /dev/urandom| tr -dc 'a-zA-Z0-9-_!@#$%^&*()_+{}|:<>?='|fold -w 12| head -n 4| grep -i '[!@#$%^&*()_+{}|:<>?=]'

This is useful if you want passwords you don't need to remember. Obviously, few people are able to remember a password like "Qc{Jb>pK)|_m". If you want a password that's just as strong but easier to remember, use a dictionary with the shuf command, like this:

Code:

shuf -n 6 --random-source=/dev/random /usr/share/dict/words

This will pick 6 random words (using /dev/urandom to create the random numbers) from the dictionary /usr/share/dict/words. /usr/share/dict/words on my machine contains about 98500 words. I have another dictionary that contains 74000 words (excluding words ending in "'s" from /usr/share/dict/words). Now let's say I create a password using 6 words from the latter dictionary (74000 words):

Code:

shuf -n 6 --random-source=/dev/random Desktop/simwords
scramblers
chiseled
therapeutic
adjuster
lamebrains
gibbeted

So the password is "ScramblersChiseledTherapeuticAdjusterLamebrainsGibbeted". The number of possible combinations are 74000^6=~10^29 which is the equivalent of a 15 character password consisting of upper/lowercase letters, numbers and special characters (like "&+-qnk_Wh<7TeNF").
Which one is the easiest to remember? They both have approximately the same entropy.