Bcrypt (useless) dictionary attack

crack.go

package main

import (
	"bufio"
	"code.google.com/p/go.crypto/bcrypt"
	"encoding/csv"
	"fmt"
	"io"
	"log"
	"os"
	"runtime"
)

var wordsList []string

func usage() {
	fmt.Fprintf(os.Stderr, "Simple bcrypt dictionary attack\nUsage: %s wordlist users.csv\n", os.Args[0])
	os.Exit(1)
}

func worker(i int, ch chan []string) {
	for {
		user := <-ch
		log.Printf("Worker %d: started %s", i, user[0])

		for i := range wordsList {
			if bcrypt.CompareHashAndPassword([]byte(user[1]), []byte(wordsList[i])) == nil {
				fmt.Printf("%s\t%s\n", user[0], wordsList[i])
				break
			}
		}
	}
}

func main() {
	if len(os.Args) != 3 {
		usage()
	}

	wordsFile, err := os.Open(os.Args[1])
	if err != nil {
		log.Fatal(err)
	}
	defer wordsFile.Close()

	usersFile, err := os.Open(os.Args[2])
	if err != nil {
		log.Fatal(err)
	}
	defer usersFile.Close()

	wordsScanner := bufio.NewScanner(wordsFile)
	for wordsScanner.Scan() {
		wordsList = append(wordsList, wordsScanner.Text())
	}
	if wordsScanner.Err() != nil {
		log.Fatal(wordsScanner.Err())
	}
	log.Printf("Read %d words\n", len(wordsList))

	usersCsv := csv.NewReader(usersFile)

	runtime.GOMAXPROCS(runtime.NumCPU())
	log.Printf("Starting %d workers\n", runtime.NumCPU())
	ch := make(chan []string)
	for i := 0; i < runtime.NumCPU(); i++ {
		go worker(i, ch)
	}

	for {
		user, err := usersCsv.Read()
		if err == io.EOF {
			break
		}
		if err != nil {
			log.Fatal(err)
		}

		ch <- user
	}
}