crunchy

Finds common flaws in passwords. Like cracklib, but written in Go.

Detects:

• Empty passwords: ErrEmpty
• Too short passwords: ErrTooShort
• Too few different characters, like "aabbccdd": ErrTooFewChars
• Systematic passwords, like "abcdefgh" or "87654321": ErrTooSystematic
• Passwords from a dictionary / wordlist: ErrDictionary
• Mangled / reversed passwords, like "p@ssw0rd" or "drowssap": ErrMangledDictionary
• Hashed dictionary words, like "5f4dcc3b5aa765d61d8327deb882cf99" (the md5sum of "password"): ErrHashedDictionary

Your system dictionaries from /usr/share/dict will be indexed. If no dictionaries were found, crunchy only relies on the regular sanity checks (ErrEmpty, ErrTooShort, ErrTooFewChars and ErrTooSystematic). On Ubuntu it is recommended to install the wordlists distributed with cracklib-runtime, on macOS you can install cracklib-words from brew. You could also install various other language dictionaries or wordlists, e.g. from skullsecurity.org.

crunchy uses the WagnerFischer algorithm to find mangled passwords in your dictionaries.

Installation

Make sure you have a working Go environment (Go 1.2 or higher is required). See the install instructions.

To install crunchy, simply run:

go get github.com/muesli/crunchy

To compile it from source:

cd $GOPATH/src/github.com/muesli/crunchy
go get -u -v
go build && go test -v

Example

package main

import (
	"github.com/muesli/crunchy"
	"fmt"
)

func main() {
    validator := crunchy.NewValidator()

    err := validator.Check("12345678")
    if err != nil {
        fmt.Printf("The password '12345678' is considered unsafe: %v\n", err)
    }

    err = validator.Check("p@ssw0rd")
    if dicterr, ok := err.(*crunchy.DictionaryError); ok {
        fmt.Printf("The password 'p@ssw0rd' is too similar to dictionary word '%s' (distance %d)\n",
            dicterr.Word, dicterr.Distance)
    }

    err = validator.Check("d1924ce3d0510b2b2b4604c99453e2e1")
    if err == nil {
        // Password is considered acceptable
        ...
    }
}

Custom Options

package main

import (
	"github.com/muesli/crunchy"
	"fmt"
)

func main() {
    validator := crunchy.NewValidatorWithOpts(crunchy.Options{
        // MinLength is the minimum length required for a valid password
        // (must be >= 1, default is 8)
        MinLength: 10,

        // MinDiff is the minimum amount of unique characters required for a valid password
        // (must be >= 1, default is 5)
        MinDiff: 8,

        // MinDist is the minimum WagnerFischer distance for mangled password dictionary lookups
        // (must be >= 0, default is 3)
        MinDist: 4,

        // Hashers will be used to find hashed passwords in dictionaries
        Hashers: []hash.Hash{md5.New(), sha1.New(), sha256.New(), sha512.New()},

        // DictionaryPath contains all the dictionaries that will be parsed
        // (default is /usr/share/dict)
        DictionaryPath: "/var/my/own/dicts",
    })
    ...
}

Development