Generate pseudo-random passwords with OpenSSL

OpenSSL comes in handy when you need to generate random passwords, for example for system accounts and services. In this short post I’ll give you a quick example on how to generate random passwords with OpenSSL in Linux (Bash), Windows and PHP…

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In this post you’ll learn how to create pseudo-random strings with OpenSSL. Random strings you can use as secure passwords.

Pseudo-random strings with OpenSSL

The OpenSSL rand command can be used to create random passwords for system accounts, services or online accounts. The rand command outputs num pseudo-random bytes after seeding the random number generator once. The -hex argument tells openssl to show the output as a hex string. You can also use -base64.

You only have to decide the byte-length of your password or string, whether you want hexadecimal or base64, and OpenSSL does all the calculations.

For example an 8 byte pseudo-random string, hex encoded output:

$ openssl rand -hex 8
28dbc04b1a90fbf4Code language: Bash (bash)

Or an 8 byte random string, base64 encoded output:

$ openssl rand -base64 8
7UON8PQIYHg=Code language: Bash (bash)

Using OpenSSL to generate random passwords in Windows

If you have installed OpenSSL on Windows, you can use the same openssl.exe command on Windows to generate a pseudo-random password or string:

PS C:\Users\Jan Reilink> &"C:\Program Files\OpenSSL-Win64\bin\openssl.exe" rand -hex 8
fa2af455f4425c9b
PS C:\Users\Jan Reilink> &"C:\Program Files\OpenSSL-Win64\bin\openssl.exe" rand -base64 8
tYHpFYAZ4C0=Code language: PowerShell (powershell)

These makes ideal passwords, easily generated with openssl.exe in Windows 11 or Windows 10 :) .

PHP OpenSSL – create a pseudo-random password with PHP and OpenSSL

In PHP you can use openssl_random_pseudo_bytes(), with bin2hex() for readability:

<?php
  var_dump(
    bin2hex(
      openssl_random_pseudo_bytes( 8, $cstrong )
    )
  );
?>Code language: PHP (php)

Yes, hexadecimal strings are all lower-case… All you need now is a way to remember these generated strings and passwords… ;-)

Random passwords with PowerShell (#PSTip – Bonus)

Use PowerShell to create a random password:

 1..14 | ForEach {
  $my_passwd = $my_passwd + [char](New-Object System.Random( (get-date).Millisecond + $_ )).next(65,127)
}
Code language: PowerShell (powershell)

or add the following Get-RandomString function to your PowerShell $PROFILE.

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