realistic password strength estimation
npm install zxcvbn3``
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zxcvbn is a password strength estimator inspired by password crackers. Through pattern matching and conservative estimation, it recognizes and weighs 30k common passwords, common names and surnames according to US census data, popular English words from Wikipedia and US television and movies, and other common patterns like dates, repeats (aaa), sequences (abcd), keyboard patterns (qwertyuiop), and l33t speak.
Consider using zxcvbn as an algorithmic alternative to password composition policy — it is more secure, flexible, and usable when sites require a minimal complexity score in place of annoying rules like "passwords must contain three of {lower, upper, numbers, symbols}".
* __More secure__: policies often fail both ways, allowing weak passwords (P@ssword1) and disallowing strong passwords.
* __More flexible__: zxcvbn allows many password styles to flourish so long as it detects sufficient complexity — passphrases are rated highly given enough uncommon words, keyboard patterns are ranked based on length and number of turns, and capitalization adds more complexity when it's unpredictaBle.
* __More usable__: zxcvbn is designed to power simple, rule-free interfaces that give instant feedback. In addition to strength estimation, zxcvbn includes minimal, targeted verbal feedback that can help guide users towards less guessable passwords.
For further detail and motivation, please refer to the USENIX Security '16 paper and presentation.
At Dropbox we use zxcvbn (Release notes) on our web, desktop, iOS and Android clients. If JavaScript doesn't work for you, others have graciously ported the library to these languages:
* zxcvbn-python (Python)
* zxcvbn-cpp (C/C++/Python/JS)
* zxcvbn-c (C/C++)
* zxcvbn-rs (Rust)
* zxcvbn-go (Go)
* zxcvbn4j (Java)
* nbvcxz (Java)
* zxcvbn-ruby (Ruby)
* zxcvbn-js (Ruby [via ExecJS])
* zxcvbn-ios (Objective-C)
* zxcvbn-cs (C#/.NET)
* szxcvbn (Scala)
* zxcvbn-php (PHP)
* zxcvbn-api (REST)
* ocaml-zxcvbn (OCaml bindings for zxcvbn-c)
Integrations with other frameworks:
* angular-zxcvbn (AngularJS)
zxcvbn is available in two versions:
* __ES2015__: This is the "default" version used for example when loading it with require("zxcvbn")
* __CommonJS__: This version can be found in the directory of the npm package and is called zxcvbn.browser.js
zxcvbn works identically on the server.
` shell`
$ npm install zxcvbn
$ node
> var zxcvbn = require('zxcvbn');
> zxcvbn('Tr0ub4dour&3');
Add zxcvbn.js to your project (using bower, npm or direct download) and import as usual:
` javascript`
requirejs(["relpath/to/zxcvbn"], function (zxcvbn) {
console.log(zxcvbn('Tr0ub4dour&3'));
});
If you're using npm and have require('zxcvbn') somewhere in your code, browserify and webpack should just work.
` shell`
$ npm install zxcvbn
$ echo "console.log(require('zxcvbn'))" > mymodule.js
$ browserify mymodule.js > browserify_bundle.js
$ webpack mymodule.js webpack_bundle.js
But we recommend against bundling zxcvbn via tools like browserify and webpack, for three reasons:
* Minified and gzipped, zxcvbn is still several hundred kilobytes. (Significantly grows bundle size.)
* Most sites will only need zxcvbn on a few pages (registration, password reset).
* Most sites won't need zxcvbn() immediately upon page load; since zxcvbn() is typically called in response to user events like filling in a password, there's ample time to fetch zxcvbn.js after initial html/css/js loads and renders.
See the performance section below for tips on loading zxcvbn stand-alone.
Tangentially, if you want to build your own standalone, consider tweaking the browserify pipeline used to generate dist/zxcvbn.js:
> ToDo
Download zxcvbn.js.
Add to your .html:
` html`
try zxcvbn interactively to see these docs in action.
` javascript`
zxcvbn(password, options?)
The optional options argument looks like this:`TypeScript`
{
user_inputs?: string[];
i18n?: i18nConfig;
language: string;
keyboard_layouts: {
german: {
layout: string;
slanted: boolean;
};
};
i18n?: {
[languageCode: string]: {
ADD_MORE_WORDS: string;
ALL_UPPERCASE: string;
AVOID_DATES: string;
AVOID_RECENT_YEARS: string;
AVOID_REPEATS: string;
AVOID_SEQUENCES: string;
AVOID_YEARS_ASSOCIATED_WITH_YOU: string;
CAPITALIZATION_DOESNT_MATTER: string;
NOT_JUST_NAMES_AND_SURNAMES: string;
NOT_JUST_ONE_WORD: string;
NO_COMMON_NAMES: string;
NO_DATES: string;
NO_NEED_FOR_SPECIAL_CHARS: string;
NO_RECENT_YEARS: string;
NO_REPEATING_REPEATS: string;
NO_REPEATS: string;
NO_REVERSED_WORDS: string;
NO_SEQUENCES: string;
NO_SHORT_PATTERNS: string;
NO_SIMILAR_PASSWORDS: string;
NO_STRAIGHT_ROWS: string;
NO_SUBSITUTIONS: string;
TOP_100_PASSWORD: string;
TOP_10_PASSWORD: string;
USE_LONGER_PATTERN: string;
USE_WORDS_NO_COMMON_PHRASES: string;
VERY_COMMON_PASSWORD: string;
}
}
}
You can specify additional keyboard layouts in order to customize the key sequence matcher. Here is an example layout string:
`
^° 1! 2" 3§ 4$ 5% 6& 7/ 8( 9) 0= ß? ´\
qQ wW eE rR tT zZ uU iI oO pP üÜ +*
aA sS dD fF gG hH jJ kK lL öÖ äÄ #'
yY xX cC vV bB nN mM ,; .: -_
``
If the layout is slanted, set to true and indent the seconf line with one space ( ), the third line with two spaces and so on.
zxcvbn() returns a result object with several properties:
` coffee
result.guesses # estimated guesses needed to crack password
result.guesses_log10 # order of magnitude of result.guesses
result.crack_times_seconds # dictionary of back-of-the-envelope crack time
# estimations, in seconds, based on a few scenarios:
{
# online attack on a service that ratelimits password auth attempts.
online_throttling_100_per_hour
# online attack on a service that doesn't ratelimit,
# or where an attacker has outsmarted ratelimiting.
online_no_throttling_10_per_second
# offline attack. assumes multiple attackers,
# proper user-unique salting, and a slow hash function
# w/ moderate work factor, such as bcrypt, scrypt, PBKDF2.
offline_slow_hashing_1e4_per_second
# offline attack with user-unique salting but a fast hash
# function like SHA-1, SHA-256 or MD5. A wide range of
# reasonable numbers anywhere from one billion - one trillion
# guesses per second, depending on number of cores and machines.
# ballparking at 10B/sec.
offline_fast_hashing_1e10_per_second
}
result.crack_times_display # same keys as result.crack_times_seconds,
# with friendlier display string values:
# "less than a second", "3 hours", "centuries", etc.
result.score # Integer from 0-4 (useful for implementing a strength bar)
0 # too guessable: risky password. (guesses < 10^3)
1 # very guessable: protection from throttled online attacks. (guesses < 10^6)
2 # somewhat guessable: protection from unthrottled online attacks. (guesses < 10^8)
3 # safely unguessable: moderate protection from offline slow-hash scenario. (guesses < 10^10)
4 # very unguessable: strong protection from offline slow-hash scenario. (guesses >= 10^10)
result.feedback # verbal feedback to help choose better passwords. set when score <= 2.
result.feedback.warning # explains what's wrong, eg. 'this is a top-10 common password'.
# not always set -- sometimes an empty string
result.feedback.suggestions # a possibly-empty list of suggestions to help choose a less
# guessable password. eg. 'Add another word or two'
result.sequence # the list of patterns that zxcvbn based the
# guess calculation on.
result.calc_time # how long it took zxcvbn to calculate an answer,
# in milliseconds.
``
The optional user_inputs argument is an array of strings that zxcvbn will treat as an extra dictionary. This can be whatever list of strings you like, but is meant for user inputs from other fields of the form, like name and email. That way a password that includes a user's personal information can be heavily penalized. This list is also good for site-specific vocabulary — Acme Brick Co. might want to include ['acme', 'brick', 'acmebrick', etc].
zxcvbn operates below human perception of delay for most input: ~5-20ms for ~25 char passwords on modern browsers/CPUs, ~100ms for passwords around 100 characters. To bound runtime latency for really long passwords, consider sending zxcvbn() only the first 100 characters or so of user input.
zxcvbn.js bundled and minified is about 400kB gzipped or 820kB uncompressed, most of which is dictionaries. Consider these tips if you're noticing page load latency on your site.
* Make sure your server is configured to compress static assets for browsers that support it. (nginx tutorial, Apache/IIS tutorial.)
Then try one of these alternatives:
1. Put your