passphraseme

A quick and simple cryptographically secure script to generate high entropy passphrases using the Electronic Frontier Foundation's wordlists, including their fandom-inspired wordlists.

Installation

pip install passphraseme

Usage

Run passphraseme with a number to generate secure passphrases using EFF's short wordlist, like this:

$ passphraseme 7
plug-scan-skate-shown-ritzy-self-bud
$ passphraseme 5
drank-amino-spoil-badge-copy

You can also optionally choose a different wordlist. Here are all of the command line arguments:

For example, you can choose to EFF's short wordlist with unique prefixes like this:

$ passphraseme -s2 5
leftover-human-podiatrist-clergyman-elk

Or you can embrace your inner nerd and use a fandom wordlist:

$ passphraseme --game-of-thrones 5
skull-putting-twenty-aid-bluntly
$ passphraseme --harry-potter 5
summoning-jealous-loads-somehow-unregistered
$ passphraseme --star-trek 5
destroying-maximum-radiation-yells-causes
$ passphraseme --star-wars 5
duels-zett-rock-silenced-blockade

You can also choose to use a custom wordlist, like this:

$ passphraseme -d /usr/share/dict/words 7
Sphinx's-congas-adjudge-revalue-scotched-decapitations-scampered

And if you prefer, you can use a custom separator, like or . instead of -:

$ passphraseme --sep " " 5
drown elder drown sport hula
$ passphraseme --sep . 5
stage.stash.speak.shack.pound

Strength of passphrases

This table shows the strength (bits of entropy) of passphraseme-generated passphrases of different lengths (1-10 words).

The brute force time is calculated like this:

I'm assuming you're using a passphrase for macOS 10.8+ (PBKDF2-SHA512) to encrypt your disk with FileVault. According to this post, the password cracking tool hashcat can guess 193,900 passphrases per second on an Amazon AWS p3.16xlarge instance, which costs $24.48 per hour.

If an attacker is willing to spend up to $1 billion per day to guess your passphrase, they can afford to run 1.7 million of these AWS instances at once, meaning they can guess ~330 billion passphrases per second. On average, a brute force attack will find the passphrase after searching half the keyspace, so the times above are how long it takes to search half the keyspace.

Note that the time "3.88e19 y" means "3.88 x 10¹⁹ years". Also note that the brute force times will vary wildly, both much quicker or much slower, depending on the hash function or KDF used -- basically, depending on what software you're using this passphrase with.

Check out calc_passphrase_strength.py to see the maths.

Licenses

The wordlists included were created by Electronic Frontier Foundation, and are distributed under the Creative Commons Attribution 3.0. For the fandom wordlists (Game of Thrones, Harry Potter, Star Trek, and Star Wars), EFF notes that "Any trademarks within the word list are the property of their respective trademark holders, who are not affiliated with the Electronic Frontier Foundation and do not sponsor or endorse these passwords."