security-and-privacy/CanvasBlocker
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Code Releases Activity

Added preference to control rng type.

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kkapsner 2016-08-06 19:17:36 +02:00
parent 447ff54222
commit 1b2c4cb487
9 changed files with 233 additions and 126 deletions
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68
lib/randomSupplies.js Normal file
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/* jslint moz: true, bitwise: true */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
(function(){
"use strict";
const persistentRnd = {};
exports.persistent = {
getRng: function(length, window){
var domain = window.document.location.host;
if (!persistentRnd[domain]){
persistentRnd[domain] = new Uint8Array(128);
for (var i = 0; i < persistentRnd[domain].length; i += 1){
persistentRnd[domain][i] = Math.floor(Math.random() * 0xFF);
}
}
var bitSet = persistentRnd[domain];
return function(value, i){
var index = value & 0x7F;
var bitIndex = ((i & 0x03) << 1) | (value >>> 7);
var bit = (bitSet[index] >>> bitIndex) & 0x01;
return value ^ bit;
};
}
};
exports.nonPersistent = {
getRng: function(length, window){
var randomI = 65536;
// var randomOffset = 0;
var randomNumbers = new Uint8Array(Math.min(65536, length));
return function(value, i){
if (randomI >= randomNumbers.length){
randomI = 0;
// randomOffset += randomNumbers.length;
if (length - i < 65536){
randomNumbers = new Uint8Array(length - i);
}
window.crypto.getRandomValues(randomNumbers);
}
var rnd = randomNumbers[randomI];
if (value >= 0x80){
value = value ^ (rnd & 0x1F);
}
else if (value >= 0x40){
value = value ^ (rnd & 0x0F);
}
else if (value >= 0x20){
value = value ^ (rnd & 0x07);
}
else if (value >= 0x10){
value = value ^ (rnd & 0x03);
}
else if (value >= 0x08){
value = value ^ (rnd & 0x01);
}
// else if (value >= 0x04){
// value = value ^ (rnd * 0x00);
// }
randomI += 1;
return value;
};
}
};
}());