--- /dev/null
+<html>
+<head>
+<style type="text/css">
+ @media print {
+ #pages > div{
+ page-break-after: always;
+ }
+
+ fieldset{
+ display: none;
+ };
+ }
+
+ @media screen {
+ #pages{
+ display: none;
+ }
+ }
+
+ td{
+ text-align: right;
+ padding: 10px;
+ }
+ td:nth-child(2n){
+ background:#ccc;
+ }
+ tr:nth-child(2) td{
+ border-width: 0 0 5px 0;
+ border-style: solid;
+
+ }
+ .half{
+ border: 1px solid black;
+ }
+ .num{
+ width: 40px;
+ }
+
+ #pages span {
+ border: 1px solid gray;
+ display: inline-block;
+ margin: 3px;
+ padding: 3px;
+ }
+ textarea{
+ width: 100%;
+ min-height: 150px;
+ }
+
+
+</style>
+<script type="text/javascript">
+var prime=257;
+function createElement(e,t){return '<'+e+'>'+t+'</'+e+'>';} // html element with content t
+function getElement(i){return document.getElementById(i);}
+function setHtmlOf(i,t){getElement(i).innerHTML=t};
+function valueOfField(i){return getElement(i).value;} // value of element with id
+
+function rand256(){
+ return Math.floor(Math.random() * 256);
+}
+
+/* Split number into the shares */
+function split(number, number_of_shares, needed) {
+ var coef = [number]; // first coefficient always equals the number itself.
+ var shares = [];
+
+ for(var coef_index = 1; coef_index < needed; coef_index++) coef[coef_index] = rand256();
+ for(var share_number = 1; share_number <= number_of_shares; share_number++) {
+ var sum = 0;
+ for (var coef_index =0; coef_index<needed; coef_index++) sum += coef[coef_index]*Math.pow(share_number,coef_index);
+ shares[share_number-1] = sum % prime;
+ }
+ return shares;
+}
+
+function collect(){
+ var divs=document.getElementsByClassName('share');
+ var shares=[];
+ var string;
+
+ // gather values from the input fields
+ for (var div_index=0; div_index<divs.length; div_index++){
+ var div=divs[div_index];
+ var inputs = div.getElementsByTagName('input');
+ var share_number=0;
+ for (var j=0; j<inputs.length;j++){
+ var input = inputs[j];
+ if (input.className == 'num') {
+ share_number=input.value;
+ } else {
+ string=input.value;
+ if (share_number>0 && string!='') {
+ var parts = string.split(' ');
+ shares[div_index] = { share_number, parts };
+ }
+ }
+ }
+ }
+
+ // the create new input fields on demand
+ if (string!=''){
+ var clone=div.cloneNode(true);
+ var inputs=clone.getElementsByTagName('input');
+ for (var j=0; j<inputs.length; j++) inputs[j].value='';
+ div.parentNode.appendChild(clone);
+ }
+ return shares;
+}
+
+function gcdD(a,b) {
+ if (b == 0) return [a, 1, 0];
+ else {
+ var n = Math.floor(a/b), c = a % b, r = gcdD(b,c);
+ return [r[0], r[2], r[1]-r[2]*n];
+ }
+}
+
+function modInverse(k) {
+ k = k % prime;
+ var r = (k < 0) ? -gcdD(prime,-k)[2] : gcdD(prime,k)[2];
+ return (prime + r) % prime;
+}
+
+function join(shares) {
+ var sum = 0;
+
+ for(j = 0; j < shares.length; j++) {
+ var numerator = 1;
+ var denominator = 1;
+ for(m = 0; m < shares.length; m++) {
+ if(j == m) continue; // If not the same value
+ numerator = (numerator * shares[m].share_number) % prime;
+ denominator = (denominator * (shares[m].share_number - shares[j].share_number)) % prime;
+ }
+ sum = (prime + sum + (shares[j].share * numerator * modInverse(denominator))) % prime;
+ }
+
+ return sum;
+}
+
+/* get the number of codes from the list of shares */
+function numberOfCodesIn(shares_list){
+ var result=null;
+ for (var i=0; i<shares_list.length; i++) {
+ if (result == null){
+ result = shares_list[i].parts.length;
+ } else {
+ result=Math.min(shares_list[i].parts.length,result);
+ }
+ }
+ return result;
+}
+
+/* fetches values from the input fields, decomposes each input string into several shares and reconstructs the original code/char for each position */
+function decode(){
+ var shares_list=collect(); // fetch shares
+ var ascii=getElement('ascii');
+ var result=getElement('result');
+
+ ascii.innerHTML='ascii: ';
+ result.innerHTML='Passphrase: ';
+
+ var codeCount = numberOfCodesIn(shares_list);
+ for (var codeIndex = 0; codeIndex<codeCount; codeIndex++){
+ shares_for_code = [];
+
+ shares_list.forEach(function(share_set){
+ var share_number = share_set.share_number;
+ var share = share_set.parts[codeIndex];
+ shares_for_code.push({ share_number, share });
+ });
+
+ var code = join(shares_for_code);
+ ascii.innerHTML += code+' ';
+ result.innerHTML+= String.fromCharCode(code);
+ }
+}
+
+/* decomposes the given secrets into single characters. Then, the ascii code of each caracter is treated as secre and split into keys */
+function secret2numbers(string){
+ var string_pos,share_number,coef,char_code,x,sum;
+ var number_of_shares = valueOfField('shares');
+ var treshold = valueOfField('treshold');
+ var results = [];
+
+ // create table elements for displaying the shares
+ var char_cells = createElement('th','char');;
+ var char_code_cells = createElement('th','ascii');;
+
+ // decompose string, for each character create secrets from asccii code
+ for (string_pos=0; string_pos<string.length;string_pos++) {
+ char_code = string.charCodeAt(string_pos);
+ char_cells += createElement('td',string[string_pos]);
+ char_code_cells += createElement('td',char_code);
+
+ results[string_pos] = split(char_code,number_of_shares,treshold);
+ }
+
+ var code=createElement('tr',char_cells)+createElement('tr',char_code_cells);
+ var pages=getElement('pages');
+ var explanation=valueOfField('explanation').replace('%n',valueOfField('treshold')).replace(/\n/g,'<br/>');
+ pages.innerHTML='';
+ for (share_number=0;share_number<number_of_shares;share_number++){
+ var line=createElement('th','share '+(share_number+1));
+ var page='';
+ for (string_pos=0;string_pos<string.length;string_pos++){
+ line+=createElement('td',results[string_pos][share_number]);
+ page+=createElement('span',results[string_pos][share_number]);
+ }
+ code+=createElement('tr',line);
+ pages.innerHTML+=createElement('div', createElement('p',explanation)+createElement('p','Your share number: '+(share_number+1))+createElement('p',page) );
+ }
+ setHtmlOf('tab',code);
+ return char_code;
+}
+</script>
+</head>
+<body>
+ <fieldset>
+ <legend>Decode secret from shares</legend>
+ <div>
+ <div class="share">
+ Share #<input class="num" value="1" />: <input class="code" onkeyup="decode();"/>
+ </div>
+ </div>
+ <p id="ascii"></p>
+ <p id="result"></p>
+ </fieldset>
+ <fieldset>
+ <legend>Create shares from secret</legend>
+ Explanation to add:<br/>
+ <textarea id="explanation" name="explanation">
+This document is a PART of a secret passphrase. At least %n of these secret parts are required to reconstruct the original passphrase.
+In the event of (enter condition here), you may meet with other secret-part holders to unite your keys.
+
+To obtain the secret phassphrase:
+<ol>
+ <li>collect at least %n secret shares</li>
+ <li>go to [url of this page]</li>
+ <li>enter the share number and the respective numbers separated by spaces</li>
+</ol>
+The passphrase obtained will give you access to [insert description of secured thing here...].
+
+[More instructions]
+
+Info: These secrets were generated using the "Shamir's Secret Sharing" algorithm.
+ </textarea><br/>
+ Passphrase parts to generate: <input id="shares" value="5" /></br>
+ Minimum nuber of shares required to recreate secret: <input id="treshold" value="3" /></br>
+ Secret: <input name="secret" onkeyup="secret2numbers(this.value);" />
+ <table id="tab"></table>
+ <ol>
+ <li>Set the explanation you want.</li>
+ <li>Enter the number of parts and shares you wish.</li>
+ <li>Enter your secret passphrase</li>
+ <li>Hit Ctrl+P or go to print via the menu</li>
+ </ol>
+ </fieldset>
+ <div id="pages"></div>
+</body>
+</html>
\ No newline at end of file
projects / shamirs_secret_web_implementation.git / commitdiff