122 lines
3.3 KiB
JavaScript
122 lines
3.3 KiB
JavaScript
const EventEmitter = require('events');
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const { hexToArray } = require('./utils');
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class FileReceiver extends EventEmitter {
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constructor() {
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super();
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}
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download() {
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return Promise.all([
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new Promise((resolve, reject) => {
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const xhr = new XMLHttpRequest();
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xhr.onprogress = event => {
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if (event.lengthComputable && event.target.status !== 404) {
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const percentComplete = Math.floor(
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event.loaded / event.total * 100
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);
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this.emit('progress', [event.loaded, event.total]);
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}
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};
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xhr.onload = function(event) {
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if (xhr.status === 404) {
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reject(
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new Error('The file has expired, or has already been deleted.')
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);
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return;
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}
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const blob = new Blob([this.response]);
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const fileReader = new FileReader();
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fileReader.onload = function() {
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const meta = JSON.parse(xhr.getResponseHeader('X-File-Metadata'));
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resolve({
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data: this.result,
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aad: meta.aad,
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filename: meta.filename,
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iv: meta.id
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});
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};
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fileReader.readAsArrayBuffer(blob);
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};
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xhr.open('get', '/assets' + location.pathname.slice(0, -1), true);
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xhr.responseType = 'blob';
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xhr.send();
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}),
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window.crypto.subtle.importKey(
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'jwk',
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{
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kty: 'oct',
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k: location.hash.slice(1),
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alg: 'A128GCM',
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ext: true
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},
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{
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name: 'AES-GCM'
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},
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true,
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['encrypt', 'decrypt']
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)
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])
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.then(([fdata, key]) => {
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this.emit('decrypting', true);
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return Promise.all([
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window.crypto.subtle
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.decrypt(
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{
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name: 'AES-GCM',
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iv: hexToArray(fdata.iv),
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additionalData: hexToArray(fdata.aad)
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},
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key,
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fdata.data
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)
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.then(decrypted => {
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this.emit('decrypting', false);
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return new Promise((resolve, reject) => {
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resolve(decrypted);
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});
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}),
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new Promise((resolve, reject) => {
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resolve(fdata.filename);
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}),
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new Promise((resolve, reject) => {
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resolve(hexToArray(fdata.aad));
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})
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]);
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})
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.then(([decrypted, fname, proposedHash]) => {
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this.emit('hashing', true);
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return window.crypto.subtle
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.digest('SHA-256', decrypted)
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.then(calculatedHash => {
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this.emit('hashing', false);
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const integrity =
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new Uint8Array(calculatedHash).toString() ===
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proposedHash.toString();
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if (!integrity) {
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return new Promise((resolve, reject) => {
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console.log('This file has been tampered with.');
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reject();
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});
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}
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return Promise.all([
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new Promise((resolve, reject) => {
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resolve(decrypted);
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}),
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new Promise((resolve, reject) => {
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resolve(fname);
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})
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]);
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});
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});
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}
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}
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module.exports = FileReceiver;
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