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Generate Passwords with openssl

You can generate some good (high entropy) passwords using this method.


Write six random bits of base64-encoded data. This will produce an eight-character string, making a good unix (crypt-based) password:


$ openssl rand -base64 6
RcqcGq4h
$

This is an example used to generate a 16-character password:


$ openssl rand -base64 12
IEoOfT/LKimAf/sd
$

When random data goes through the base encoding process, the string output is always a multiple of four possibly padded on the end with one or more ‘=’ characters. So, if you want a password that is not a multiple of four, you need to artificially chop it where you want it.

Below is an example used to generate a 37-character password.

With Cut:


$ openssl rand -base64 37 | cut -c1-37
X/UhqF1I9qO57Uz8hPufpvbOLYCeuuvqnerUM
$

Or sed:


$ openssl rand -base64 37 | sed -e ‘s/^\(.\{37\}\).*/\1/g’
sAPpFoGnbXnJrQc8Cl/QqrNwn0QK3hHrgANt1
$

Or awk:


$ openssl rand -base64 37 | awk ‘BEGIN{FS=””} {for (i=1;i<=37;i++) printf("%s",$i);} {printf "\n"}'
WhGWSCp8Y2uilxWfOfAyQXa4QqlE78uJeH3sn
$

The Conversation

Follow the reactions below and share your own thoughts.

  • gnulinux

    Thats brilliant.

    keep up good work.

  • +françois

    This is the kind of snippet that make me love linux!
    I was looking to generate random passwords in my text editor and now a simple CTRL + p does it for me

    ( with gedit: Tools-> ExternalTools)

    thanks