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