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flask_hashcash.js
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flask_hashcash.js
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function createCookie(name,value,days) {
var expires = "";
if (days) {
var date = new Date();
date.setTime(date.getTime() + (days*24*60*60*1000));
expires = "; expires=" + date.toUTCString();
}
document.cookie = name + "=" + value + expires + "; path=/";
}
function readCookie(name) {
var nameEQ = name + "=";
var ca = document.cookie.split(';');
for(var i=0;i < ca.length;i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
function hash(puzzle,solution){
return Sha1.hash(puzzle.concat(solution)); // btw this is in binary
}
function findHashcashSolution(params = {}){
default_params = {puzzle:null, difficulty:5, solution:0, callback:null};
for(k in default_params)
if(params[k] == undefined)
params[k] = default_params[k];
var puzzle = params.puzzle,
difficulty = params.difficulty,
solution = params.solution,
callback = params.callback;
// read current puzzle from cookies
if(puzzle == null)
puzzle = readCookie('hashcash_puzzle');
if(puzzle == null)
return;
// if you have cached solution no need to continue seach
if(hash(puzzle, readCookie('hashcash_solution')) == Array(difficulty+1).join("0"))
return;
// check solution from params
var h = hash(puzzle,solution);
// if the hash starts with *difficulty*(default = 1) of zeros - solution verified
if(h.substring(0,difficulty) == Array(difficulty+1).join("0")){
createCookie('hashcash_solution', solution); //store it as cookie
if(callback)
callback.call(solution);
}else
// continuing search
setTimeout(function(){
params.solution += 1 // try next number
findHashcashSolution(params);
}, 0);
}