Copied from http://preshing.com/files/xkcd_pw.js.php

xkcd_pw.js

//-------------------------------------------------------------------
// Copyright (c) 2011, Jeff Preshing
// http://preshing.com/20110811/xkcd-password-generator
// All rights reserved.
//
// Some parts based on http://www.mytsoftware.com/dailyproject/PassGen/entropy.js, copyright 2003 David Finch.
// 
// Released under the Modified BSD License:
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of the <organization> nor the
//       names of its contributors may be used to endorse or promote products
//       derived from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//-------------------------------------------------------------------

// A SHA-1 hash generated on the server which is unique for each visit:
var xkcd_pw_gen_server_hash = "60c8945bce349bed513fc485be511f9b1e29ed02";

var xkcd_pw_gen_wordlist = [
"ability","able","aboard","about","above","accept","accident","according",
"account","accurate","acres","across","act","action","active","activity",
"actual","actually","add","addition","additional","adjective","adult","adventure",
"advice","affect","afraid","after","afternoon","again","against","age",
"ago","agree","ahead","aid","air","airplane","alike","alive",
"all","allow","almost","alone","along","aloud","alphabet","already",
"also","although","am","among","amount","ancient","angle","angry",
"animal","announced","another","answer","ants","any","anybody","anyone",
"anything","anyway","anywhere","apart","apartment","appearance","apple","applied",
"appropriate","are","area","arm","army","around","arrange","arrangement",
"arrive","arrow","art","article","as","aside","ask","asleep",
"at","ate","atmosphere","atom","atomic","attached","attack","attempt",
"attention","audience","author","automobile","available","average","avoid","aware",
"away","baby","back","bad","badly","bag","balance","ball",
"balloon","band","bank","bar","bare","bark","barn","base",
"baseball","basic","basis","basket","bat","battle","be","bean",
"bear","beat","beautiful","beauty","became","because","become","becoming",
"bee","been","before","began","beginning","begun","behavior","behind",
"being","believed","bell","belong","below","belt","bend","beneath",
"bent","beside","best","bet","better","between","beyond","bicycle",
"bigger","biggest","bill","birds","birth","birthday","bit","bite",
"black","blank","blanket","blew","blind","block","blood","blow",
"blue","board","boat","body","bone","book","border","born",
"both","bottle","bottom","bound","bow","bowl","box","boy",
"brain","branch","brass","brave","bread","break","breakfast","breath",
"breathe","breathing","breeze","brick","bridge","brief","bright","bring",
"broad","broke","broken","brother","brought","brown","brush","buffalo",
"build","building","built","buried","burn","burst","bus","bush",
"business","busy","but","butter","buy","by","cabin","cage",
"cake","call","calm","came","camera","camp","can","canal",
"cannot","cap","capital","captain","captured","car","carbon","card",
"care","careful","carefully","carried","carry","case","cast","castle",
"cat","catch","cattle","caught","cause","cave","cell","cent",
"center","central","century","certain","certainly","chain","chair","chamber",
"chance","change","changing","chapter","character","characteristic","charge","chart",
"check","cheese","chemical","chest","chicken","chief","child","children",
"choice","choose","chose","chosen","church","circle","circus","citizen",
"city","class","classroom","claws","clay","clean","clear","clearly",
"climate","climb","clock","close","closely","closer","cloth","clothes",
"clothing","cloud","club","coach","coal","coast","coat","coffee",
"cold","collect","college","colony","color","column","combination","combine",
"come","comfortable","coming","command","common","community","company","compare",
"compass","complete","completely","complex","composed","composition","compound","concerned",
"condition","congress","connected","consider","consist","consonant","constantly","construction",
"contain","continent","continued","contrast","control","conversation","cook","cookies",
"cool","copper","copy","corn","corner","correct","correctly","cost",
"cotton","could","count","country","couple","courage","course","court",
"cover","cow","cowboy","crack","cream","create","creature","crew",
"crop","cross","crowd","cry","cup","curious","current","curve",
"customs","cut","cutting","daily","damage","dance","danger","dangerous",
"dark","darkness","date","daughter","dawn","day","dead","deal",
"dear","death","decide","declared","deep","deeply","deer","definition",
"degree","depend","depth","describe","desert","design","desk","detail",
"determine","develop","development","diagram","diameter","did","die","differ",
"difference","different","difficult","difficulty","dig","dinner","direct","direction",
"directly","dirt","dirty","disappear","discover","discovery","discuss","discussion",
"disease","dish","distance","distant","divide","division","do","doctor",
"does","dog","doing","doll","dollar","done","donkey","door",
"dot","double","doubt","down","dozen","draw","drawn","dream",
"dress","drew","dried","drink","drive","driven","driver","driving",
"drop","dropped","drove","dry","duck","due","dug","dull",
"during","dust","duty","each","eager","ear","earlier","early",
"earn","earth","easier","easily","east","easy","eat","eaten",
"edge","education","effect","effort","egg","eight","either","electric",
"electricity","element","elephant","eleven","else","empty","end","enemy",
"energy","engine","engineer","enjoy","enough","enter","entire","entirely",
"environment","equal","equally","equator","equipment","escape","especially","essential",
"establish","even","evening","event","eventually","ever","every","everybody",
"everyone","everything","everywhere","evidence","exact","exactly","examine","example",
"excellent","except","exchange","excited","excitement","exciting","exclaimed","exercise",
"exist","expect","experience","experiment","explain","explanation","explore","express",
"expression","extra","eye","face","facing","fact","factor","factory",
"failed","fair","fairly","fall","fallen","familiar","family","famous",
"far","farm","farmer","farther","fast","fastened","faster","fat",
"father","favorite","fear","feathers","feature","fed","feed","feel",
"feet","fell","fellow","felt","fence","few","fewer","field",
"fierce","fifteen","fifth","fifty","fight","fighting","figure","fill",
"film","final","finally","find","fine","finest","finger","finish",
"fire","fireplace","firm","first","fish","five","fix","flag",
"flame","flat","flew","flies","flight","floating","floor","flow",
"flower","fly","fog","folks","follow","food","foot","football",
"for","force","foreign","forest","forget","forgot","forgotten","form",
"former","fort","forth","forty","forward","fought","found","four",
"fourth","fox","frame","free","freedom","frequently","fresh","friend",
"friendly","frighten","frog","from","front","frozen","fruit","fuel",
"full","fully","fun","function","funny","fur","furniture","further",
"future","gain","game","garage","garden","gas","gasoline","gate",
"gather","gave","general","generally","gentle","gently","get","getting",
"giant","gift","girl","give","given","giving","glad","glass",
"globe","go","goes","gold","golden","gone","good","goose",
"got","government","grabbed","grade","gradually","grain","grandfather","grandmother",
"graph","grass","gravity","gray","great","greater","greatest","greatly",
"green","grew","ground","group","grow","grown","growth","guard",
"guess","guide","gulf","gun","habit","had","hair","half",
"halfway","hall","hand","handle","handsome","hang","happen","happened",
"happily","happy","harbor","hard","harder","hardly","has","hat",
"have","having","hay","he","headed","heading","health","heard",
"hearing","heart","heat","heavy","height","held","hello","help",
"helpful","her","herd","here","herself","hidden","hide","high",
"higher","highest","highway","hill","him","himself","his","history",
"hit","hold","hole","hollow","home","honor","hope","horn",
"horse","hospital","hot","hour","house","how","however","huge",
"human","hundred","hung","hungry","hunt","hunter","hurried","hurry",
"hurt","husband","ice","idea","identity","if","ill","image",
"imagine","immediately","importance","important","impossible","improve","in","inch",
"include","including","income","increase","indeed","independent","indicate","individual",
"industrial","industry","influence","information","inside","instance","instant","instead",
"instrument","interest","interior","into","introduced","invented","involved","iron",
"is","island","it","its","itself","jack","jar","jet",
"job","join","joined","journey","joy","judge","jump","jungle",
"just","keep","kept","key","kids","kill","kind","kitchen",
"knew","knife","know","knowledge","known","label","labor","lack",
"lady","laid","lake","lamp","land","language","large","larger",
"largest","last","late","later","laugh","law","lay","layers",
"lead","leader","leaf","learn","least","leather","leave","leaving",
"led","left","leg","length","lesson","let","letter","level",
"library","lie","life","lift","light","like","likely","limited",
"line","lion","lips","liquid","list","listen","little","live",
"living","load","local","locate","location","log","lonely","long",
"longer","look","loose","lose","loss","lost","lot","loud",
"love","lovely","low","lower","luck","lucky","lunch","lungs",
"lying","machine","machinery","mad","made","magic","magnet","mail",
"main","mainly","major","make","making","man","managed","manner",
"manufacturing","many","map","mark","market","married","mass","massage",
"master","material","mathematics","matter","may","maybe","me","meal",
"mean","means","meant","measure","meat","medicine","meet","melted",
"member","memory","men","mental","merely","met","metal","method",
"mice","middle","might","mighty","mile","military","milk","mill",
"mind","mine","minerals","minute","mirror","missing","mission","mistake",
"mix","mixture","model","modern","molecular","moment","money","monkey",
"month","mood","moon","more","morning","most","mostly","mother",
"motion","motor","mountain","mouse","mouth","move","movement","movie",
"moving","mud","muscle","music","musical","must","my","myself",
"mysterious","nails","name","nation","national","native","natural","naturally",
"nature","near","nearby","nearer","nearest","nearly","necessary","neck",
"needed","needle","needs","negative","neighbor","neighborhood","nervous","nest",
"never","new","news","newspaper","next","nice","night","nine",
"no","nobody","nodded","noise","none","noon","nor","north",
"nose","not","note","noted","nothing","notice","noun","now",
"number","numeral","nuts","object","observe","obtain","occasionally","occur",
"ocean","of","off","offer","office","officer","official","oil",
"old","older","oldest","on","once","one","only","onto",
"open","operation","opinion","opportunity","opposite","or","orange","orbit",
"order","ordinary","organization","organized","origin","original","other","ought",
"our","ourselves","out","outer","outline","outside","over","own",
"owner","oxygen","pack","package","page","paid","pain","paint",
"pair","palace","pale","pan","paper","paragraph","parallel","parent",
"park","part","particles","particular","particularly","partly","parts","party",
"pass","passage","past","path","pattern","pay","peace","pen",
"pencil","people","per","percent","perfect","perfectly","perhaps","period",
"person","personal","pet","phrase","physical","piano","pick","picture",
"pictured","pie","piece","pig","pile","pilot","pine","pink",
"pipe","pitch","place","plain","plan","plane","planet","planned",
"planning","plant","plastic","plate","plates","play","pleasant","please",
"pleasure","plenty","plural","plus","pocket","poem","poet","poetry",
"point","pole","police","policeman","political","pond","pony","pool",
"poor","popular","population","porch","port","position","positive","possible",
"possibly","post","pot","potatoes","pound","pour","powder","power",
"powerful","practical","practice","prepare","present","president","press","pressure",
"pretty","prevent","previous","price","pride","primitive","principal","principle",
"printed","private","prize","probably","problem","process","produce","product",
"production","program","progress","promised","proper","properly","property","protection",
"proud","prove","provide","public","pull","pupil","pure","purple",
"purpose","push","put","putting","quarter","queen","question","quick",
"quickly","quiet","quietly","quite","rabbit","race","radio","railroad",
"rain","raise","ran","ranch","range","rapidly","rate","rather",
"raw","rays","reach","read","reader","ready","real","realize",
"rear","reason","recall","receive","recent","recently","recognize","record",
"red","refer","refused","region","regular","related","relationship","religious",
"remain","remarkable","remember","remove","repeat","replace","replied","report",
"represent","require","research","respect","rest","result","return","review",
"rhyme","rhythm","rice","rich","ride","riding","right","ring",
"rise","rising","river","road","roar","rock","rocket","rocky",
"rod","roll","roof","room","root","rope","rose","rough",
"round","route","row","rubbed","rubber","rule","ruler","run",
"running","rush","sad","saddle","safe","safety","said","sail",
"sale","salmon","salt","same","sand","sang","sat","satellites",
"satisfied","save","saved","saw","say","scale","scared","scene",
"school","science","scientific","scientist","score","screen","sea","search",
"season","seat","second","secret","section","see","seed","seeing",
"seems","seen","seldom","select","selection","sell","send","sense",
"sent","sentence","separate","series","serious","serve","service","sets",
"setting","settle","settlers","seven","several","shade","shadow","shake",
"shaking","shall","shallow","shape","share","sharp","she","sheep",
"sheet","shelf","shells","shelter","shine","shinning","ship","shirt",
"shoe","shoot","shop","shore","short","shorter","shot","should",
"shoulder","shout","show","shown","shut","sick","sides","sight",
"sign","signal","silence","silent","silk","silly","silver","similar",
"simple","simplest","simply","since","sing","single","sink","sister",
"sit","sitting","situation","six","size","skill","skin","sky",
"slabs","slave","sleep","slept","slide","slight","slightly","slip",
"slipped","slope","slow","slowly","small","smaller","smallest","smell",
"smile","smoke","smooth","snake","snow","so","soap","social",
"society","soft","softly","soil","solar","sold","soldier","solid",
"solution","solve","some","somebody","somehow","someone","something","sometime",
"somewhere","son","song","soon","sort","sound","source","south",
"southern","space","speak","special","species","specific","speech","speed",
"spell","spend","spent","spider","spin","spirit","spite","split",
"spoken","sport","spread","spring","square","stage","stairs","stand",
"standard","star","stared","start","state","statement","station","stay",
"steady","steam","steel","steep","stems","step","stepped","stick",
"stiff","still","stock","stomach","stone","stood","stop","stopped",
"store","storm","story","stove","straight","strange","stranger","straw",
"stream","street","strength","stretch","strike","string","strip","strong",
"stronger","struck","structure","struggle","stuck","student","studied","studying",
"subject","substance","success","successful","such","sudden","suddenly","sugar",
"suggest","suit","sum","summer","sun","sunlight","supper","supply",
"support","suppose","sure","surface","surprise","surrounded","swam","sweet",
"swept","swim","swimming","swing","swung","syllable","symbol","system",
"table","tail","take","taken","tales","talk","tall","tank",
"tape","task","taste","taught","tax","tea","teach","teacher",
"team","tears","teeth","telephone","television","tell","temperature","ten",
"tent","term","terrible","test","than","thank","that","thee",
"them","themselves","then","theory","there","therefore","these","they",
"thick","thin","thing","think","third","thirty","this","those",
"thou","though","thought","thousand","thread","three","threw","throat",
"through","throughout","throw","thrown","thumb","thus","thy","tide",
"tie","tight","tightly","till","time","tin","tiny","tip",
"tired","title","to","tobacco","today","together","told","tomorrow",
"tone","tongue","tonight","too","took","tool","top","topic",
"torn","total","touch","toward","tower","town","toy","trace",
"track","trade","traffic","trail","train","transportation","trap","travel",
"treated","tree","triangle","tribe","trick","tried","trip","troops",
"tropical","trouble","truck","trunk","truth","try","tube","tune",
"turn","twelve","twenty","twice","two","type","typical","uncle",
"under","underline","understanding","unhappy","union","unit","universe","unknown",
"unless","until","unusual","up","upon","upper","upward","us",
"use","useful","using","usual","usually","valley","valuable","value",
"vapor","variety","various","vast","vegetable","verb","vertical","very",
"vessels","victory","view","village","visit","visitor","voice","volume",
"vote","vowel","voyage","wagon","wait","walk","wall","want",
"war","warm","warn","was","wash","waste","watch","water",
"wave","way","we","weak","wealth","wear","weather","week",
"weigh","weight","welcome","well","went","were","west","western",
"wet","whale","what","whatever","wheat","wheel","when","whenever",
"where","wherever","whether","which","while","whispered","whistle","white",
"who","whole","whom","whose","why","wide","widely","wife",
"wild","will","willing","win","wind","window","wing","winter",
"wire","wise","wish","with","within","without","wolf","women",
"won","wonder","wonderful","wood","wooden","wool","word","wore",
"work","worker","world","worried","worry","worse","worth","would",
"wrapped","write","writer","writing","written","wrong","wrote","yard",
"year","yellow","yes","yesterday","yet","you","young","younger",
"your","yourself","youth","zero","zoo"
];

// Get some entropy from the system clock:
function xkcd_pw_gen_time_ent()
{
    var d = 1 * new Date();
    var i = 0;
    while (1 * new Date() == d)
        i++; // Measure iterations until next tick
    return "" + d + i;
}

// Return a pseudorandom array of four 32-bit integers:
function xkcd_pw_gen_create_hash()
{
    // Entropy string built in a manner inspired by David Finch:
    var entropy = xkcd_pw_gen_server_hash + xkcd_pw_gen_time_ent();
    entropy += navigator.userAgent + Math.random() + Math.random() + screen.width + screen.height;
    if (document.all)
        entropy = entropy + document.body.clientWidth + document.body.clientHeight + document.body.scrollWidth + document.body.scrollHeight;
    else
        entropy = entropy + window.innerWidth + window.innerHeight + window.width + window.height;
    entropy += xkcd_pw_gen_time_ent();
        
    // Hash and convert to 32-bit integers:
    var hexString = hex_sha1(entropy); // from sha1-min.js
    var result = [];
    for (var i = 0; i < 32; i += 8)
    {
        result.push(parseInt(hexString.substr(i, 8), 16));
    }
    return result;
}

// Generate a new passphrase and update the document:
function xkcd_pw_gen()
{
    var hash = xkcd_pw_gen_create_hash();
    var choices = [];
    for (var w = 0; w < 4; w++)
    {
        var jsRandom = Math.floor(Math.random() * 0x100000000);
        var index = ((jsRandom ^ hash[w]) + 0x100000000) % xkcd_pw_gen_wordlist.length;
        choices.push(xkcd_pw_gen_wordlist[index]);
    }
    var resultSpan = document.getElementById("xkcd_pw_gen_result");
    resultSpan.innerText = resultSpan.textContent = choices.join(" ");
}

xkcd_pw_gen();