import Nanobus from 'nanobus'; import { arrayToB64, b64ToArray, bytes } from './utils'; export default class FileReceiver extends Nanobus { constructor(url, file) { super('FileReceiver'); this.secretKeyPromise = window.crypto.subtle.importKey( 'raw', b64ToArray(file.key), 'HKDF', false, ['deriveKey'] ); this.encryptKeyPromise = this.secretKeyPromise.then(sk => { const encoder = new TextEncoder(); return window.crypto.subtle.deriveKey( { name: 'HKDF', salt: new Uint8Array(), info: encoder.encode('encryption'), hash: 'SHA-256' }, sk, { name: 'AES-GCM', length: 128 }, false, ['decrypt'] ); }); if (file.pwd) { const encoder = new TextEncoder(); this.authKeyPromise = window.crypto.subtle .importKey( 'raw', encoder.encode(file.password), { name: 'PBKDF2' }, false, ['deriveKey'] ) .then(pwdKey => window.crypto.subtle.deriveKey( { name: 'PBKDF2', salt: encoder.encode(file.url), iterations: 100, hash: 'SHA-256' }, pwdKey, { name: 'HMAC', hash: 'SHA-256' }, true, ['sign'] ) ); } else { this.authKeyPromise = this.secretKeyPromise.then(sk => { const encoder = new TextEncoder(); return window.crypto.subtle.deriveKey( { name: 'HKDF', salt: new Uint8Array(), info: encoder.encode('authentication'), hash: 'SHA-256' }, sk, { name: 'HMAC', hash: { name: 'SHA-256' } }, false, ['sign'] ); }); } this.metaKeyPromise = this.secretKeyPromise.then(sk => { const encoder = new TextEncoder(); return window.crypto.subtle.deriveKey( { name: 'HKDF', salt: new Uint8Array(), info: encoder.encode('metadata'), hash: 'SHA-256' }, sk, { name: 'AES-GCM', length: 128 }, false, ['decrypt'] ); }); this.file = file; this.url = url; this.msg = 'fileSizeProgress'; this.state = 'initialized'; this.progress = [0, 1]; } get progressRatio() { return this.progress[0] / this.progress[1]; } get sizes() { return { partialSize: bytes(this.progress[0]), totalSize: bytes(this.progress[1]) }; } cancel() { // TODO } fetchMetadata(sig) { return new Promise((resolve, reject) => { const xhr = new XMLHttpRequest(); xhr.onreadystatechange = () => { if (xhr.readyState === XMLHttpRequest.DONE) { const nonce = xhr.getResponseHeader('WWW-Authenticate').split(' ')[1]; this.file.nonce = nonce; if (xhr.status === 200) { return resolve(xhr.response); } reject(new Error(xhr.status)); } }; xhr.onerror = () => reject(new Error(0)); xhr.ontimeout = () => reject(new Error(0)); xhr.open('get', `/api/metadata/${this.file.id}`); xhr.setRequestHeader('Authorization', `send-v1 ${arrayToB64(sig)}`); xhr.responseType = 'json'; xhr.timeout = 2000; xhr.send(); }); } async getMetadata(nonce) { try { const authKey = await this.authKeyPromise; const sig = await window.crypto.subtle.sign( { name: 'HMAC' }, authKey, b64ToArray(nonce) ); const data = await this.fetchMetadata(new Uint8Array(sig)); const metaKey = await this.metaKeyPromise; const json = await window.crypto.subtle.decrypt( { name: 'AES-GCM', iv: new Uint8Array(12), tagLength: 128 }, metaKey, b64ToArray(data.metadata) ); const decoder = new TextDecoder(); const meta = JSON.parse(decoder.decode(json)); this.file.name = meta.name; this.file.type = meta.type; this.file.iv = meta.iv; this.file.size = data.size; this.file.ttl = data.ttl; this.state = 'ready'; } catch (e) { this.state = 'invalid'; throw e; } } downloadFile(sig) { return new Promise((resolve, reject) => { const xhr = new XMLHttpRequest(); xhr.onprogress = event => { if (event.lengthComputable && event.target.status !== 404) { this.progress = [event.loaded, event.total]; this.emit('progress', this.progress); } }; xhr.onload = event => { if (xhr.status === 404) { reject(new Error('notfound')); return; } if (xhr.status !== 200) { return reject(new Error(xhr.status)); } const blob = new Blob([xhr.response]); const fileReader = new FileReader(); fileReader.onload = function() { resolve(this.result); }; fileReader.readAsArrayBuffer(blob); }; xhr.open('get', this.url); xhr.setRequestHeader('Authorization', `send-v1 ${arrayToB64(sig)}`); xhr.responseType = 'blob'; xhr.send(); }); } async download(nonce) { this.state = 'downloading'; this.emit('progress', this.progress); try { const encryptKey = await this.encryptKeyPromise; const authKey = await this.authKeyPromise; const sig = await window.crypto.subtle.sign( { name: 'HMAC' }, authKey, b64ToArray(nonce) ); const ciphertext = await this.downloadFile(new Uint8Array(sig)); this.msg = 'decryptingFile'; this.emit('decrypting'); const plaintext = await window.crypto.subtle.decrypt( { name: 'AES-GCM', iv: b64ToArray(this.file.iv), tagLength: 128 }, encryptKey, ciphertext ); this.msg = 'downloadFinish'; this.state = 'complete'; return { plaintext, name: decodeURIComponent(this.file.name), type: this.file.type }; } catch (e) { this.state = 'invalid'; throw e; } } }