passphraseme 0.1.1

A quick and simple cryptographically secure script to generate high entropy passphrases using the Electronic Frontier Foundation's wordlists

passphraseme

A quick and simple cryptographically secure script to generate high entropy passphrases using the Electronic Frontier Foundation's wordlists.

Installation

pip3 install passphraseme

Usage

Run passphraseme with a number to generate secure passphrases, like this:

$ passphraseme 7
banana stopwatch appealing germinate survival retired comma
$ passphraseme 5
borrower harvest stature entity blimp

By default, passphraseme uses EFF's long wordlist. But optionally, you can choose to use one of EFF's two short wordlists, like this:

$ passphraseme -s1 5
glide canal flag sage those
$ passphraseme -s2 5
optical anonymous nirvana agitate feudalist

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

$ passphraseme -d /usr/share/dict/words 7
leading's Oz's caesareans lactate eloped interposed wowed

Strength of passphrases

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

	Bits of entropy/word	1	2	3	4	5	6	7	8	9	10
EFF large wordlist (default)	12.9	12.9 (0 s)	25.8 (0 s)	38.7 (1 s)	51.6 (86 m)	64.5 (1.2 y)	77.4 (9.5k y)	90.3 (73M y)	103.2 (560B y)	116.1 (4.2e15 y)	129 (3.2e19 y)
EFF short wordlists	10.3	10.3 (0 s)	20.6 (0 s)	30.9 (0 s)	41.2 (4 s)	51.5 (80 m)	61.8 (70 d)	72.1 (243 y)	82.4 (306k y)	92.7 (386M y)	103 (4.8e11 y)

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 "3.2e19 y" means "3.2 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.