For cracking the hash in http://xkcd.com/1193/

break_hash.go

package main

import (
    "fmt"
	"crypto/skein" //https://github.com/wernerd/Skein3Fish
	"encoding/hex"
	"os"
	"bufio"
	"io"
	"strings"
)

const goal string = "5b4da95f5fa08280fc9879df44f418c8f9f12ba424b7757de02bbdfbae0d4c4fdf9317c80cc5fe04c6429073466cf29706b8c25999ddd2f6540d4475cc977b87f4757be023f19b8f4035d7722886b78869826de916a79cf9c94cc79cd4347d24b567aa3e2390a573a373a48a5e676640c79cc70197e1c5e7f902fb53ca1858b6"

func hash (in string) []byte {
	var empty []byte
	skein, _ := skein.NewMac(1024, 1024, empty)
	skein.Update([]byte(in))
	res := skein.DoFinal()
	return res
}

func compBytes (a, b []byte) int {
	res := 0
	for i := 0; i < len(a); i++ {
		res += compByte(a[i], b[i])
	}
	return res
}

func compByte (a, b byte) int {
	res := 0
	for i := uint32(0); i < 8; i++ {
		if ((a >> i) & 1) != ((b >> i) & 1) {
			res += 1;
		}
	}
	return res
}

func main() {
	best := 1000
	goalbytes, _ := hex.DecodeString(goal)

	reader := bufio.NewReader(os.Stdin)

	for line, err := reader.ReadString('\n'); err != io.EOF ; line, err = reader.ReadString('\n'){
		word := strings.Split(line, "\n")[0]
		res := compBytes(hash(word), goalbytes)
		if res < best {
			fmt.Printf("%d '%s'\n", res, word)
			best = res
		}
	}
}