posp test

posptest.js

const crypto = require('crypto');


function proofOfSpace(password, salt) {
	var iterate = 500000; // gives ~30Mo on sha256
	var series = [];
	var spaceSize = 0;

	console.log("Generating POS password");
	var last = '';
	for(var a=0; a<iterate; a++) {
		var hash = crypto.createHash('sha256');
		hash.update(last);
		hash.update(salt);
		hash.update(password);
		var res = hash.digest('hex');
		series.push(res);
		last = res;
		spaceSize += res.length;
	}

	function showMeYouHaveTheRest(block, pos) {
		var hash = crypto.createHash('sha256');
		var last = block;
		for(var a=pos; a<series.length; a++) {
			hash.update(last);
			hash.update(series[pos]);
			hash.update(salt);
			hash.update(password);
			last = hash.digest('hex');
		}
		return(last);
	}

	for(var a=iterate-1; a>=0; a--) {
		var pos = series[a];
		if(!pos) {
			console.log("Error there");
			process.exit(0);
		}

		var hash = crypto.createHash('sha256');
		hash.update(last);
		hash.update(pos);
		hash.update(salt);
		hash.update(password);
		hash.update(showMeYouHaveTheRest(last, pos));
		var res = hash.digest('hex');
		series.push(res);
		last = res;
	}

	console.log("POS password computation done gives "+last+" and spending "+(spaceSize/1024/1024)+'MB');

	return("$POSPv1:"+last);
}

proofOfSpace('test', 'test');