2eedcb8ff6
The browser app must read and write the same encrypted files as the desktop Pithos. web/lib/crypt.js reimplements core/crypt.js on Web Crypto (AES-SIV and CMAC built from AES-CBC with a zero IV and AES-CTR, since Web Crypto has neither), and web/lib/sigv4.js the SigV4 signing. Cross-tests: the RFC 5297 vector, identical drive keys and names, bodies encrypted on one side and opened on the other (empty, chunk-edge and multi-chunk files, ranges), tamper and wrong-path rejection, and equal SigV4 headers and presigned URLs.
77 lines
3.6 KiB
JavaScript
77 lines
3.6 KiB
JavaScript
// AWS SigV4 for the browser app: the same canonical form as core/s3.js
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// (path-style, us-east-1, UNSIGNED-PAYLOAD for bodies), on Web Crypto.
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// Browsers set Host themselves, so it is signed but not returned.
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const subtle = globalThis.crypto.subtle;
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const enc = new TextEncoder();
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export const REGION = 'us-east-1';
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export const SERVICE = 's3';
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const hex = (b) => Array.from(new Uint8Array(b), (x) => x.toString(16).padStart(2, '0')).join('');
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const sha256 = async (s) => hex(await subtle.digest('SHA-256', typeof s === 'string' ? enc.encode(s) : s));
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async function hmac(key, msg) {
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const k = await subtle.importKey('raw', typeof key === 'string' ? enc.encode(key) : key, { name: 'HMAC', hash: 'SHA-256' }, false, ['sign']);
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return new Uint8Array(await subtle.sign('HMAC', k, enc.encode(msg)));
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}
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export function uriEncode(str, keepSlash) {
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const out = encodeURIComponent(str).replace(/[!'()*]/g, (c) => '%' + c.charCodeAt(0).toString(16).toUpperCase());
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return keepSlash ? out.replace(/%2F/g, '/') : out;
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}
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export function canonicalQuery(query) {
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return Object.keys(query).sort().map((k) => `${uriEncode(k)}=${uriEncode(String(query[k] ?? ''))}`).join('&');
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}
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export const amzDate = (d = new Date()) => d.toISOString().replace(/[-:]/g, '').replace(/\.\d{3}/, '');
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export function objectPath(bucket, key) {
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return '/' + uriEncode(bucket) + (key != null ? '/' + uriEncode(key, true) : '');
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}
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const signingKeys = new Map();
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async function signingKey(secret, date) {
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const id = `${date}:${secret}`;
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let k = signingKeys.get(id);
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if (!k) {
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k = await hmac(await hmac(await hmac(await hmac('AWS4' + secret, date), REGION), SERVICE), 'aws4_request');
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signingKeys.clear();
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signingKeys.set(id, k);
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}
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return k;
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}
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// Headers to send (lower-case, without host) for a signed request.
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export async function sign({ host, accessKeyId, secretKey }, method, path, query = {}, headers = {}, { now = amzDate(), payloadHash = 'UNSIGNED-PAYLOAD' } = {}) {
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const date = now.slice(0, 8);
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const h = { ...headers, host, 'x-amz-date': now, 'x-amz-content-sha256': payloadHash };
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const lower = Object.fromEntries(Object.entries(h).map(([k, v]) => [k.toLowerCase(), String(v).trim()]));
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const names = Object.keys(lower).sort();
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const signed = names.join(';');
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const canonical = [method, path, canonicalQuery(query), names.map((n) => `${n}:${lower[n]}\n`).join(''), signed, payloadHash].join('\n');
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const scope = `${date}/${REGION}/${SERVICE}/aws4_request`;
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const toSign = ['AWS4-HMAC-SHA256', now, scope, await sha256(canonical)].join('\n');
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const sig = hex(await hmac(await signingKey(secretKey, date), toSign));
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lower.authorization = `AWS4-HMAC-SHA256 Credential=${accessKeyId}/${scope}, SignedHeaders=${signed}, Signature=${sig}`;
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delete lower.host;
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return lower;
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}
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// A presigned GET (for <audio>/<video>/<img> sources and downloads).
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export async function presign({ origin, host, accessKeyId, secretKey }, bucket, key, expiresSec = 3600, now = amzDate()) {
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const date = now.slice(0, 8);
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const scope = `${date}/${REGION}/${SERVICE}/aws4_request`;
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const path = objectPath(bucket, key);
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const query = {
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'X-Amz-Algorithm': 'AWS4-HMAC-SHA256',
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'X-Amz-Credential': `${accessKeyId}/${scope}`,
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'X-Amz-Date': now,
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'X-Amz-Expires': String(Math.min(Math.max(1, expiresSec | 0), 604800)),
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'X-Amz-SignedHeaders': 'host',
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};
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const canonical = ['GET', path, canonicalQuery(query), `host:${host}\n`, 'host', 'UNSIGNED-PAYLOAD'].join('\n');
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const toSign = ['AWS4-HMAC-SHA256', now, scope, await sha256(canonical)].join('\n');
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query['X-Amz-Signature'] = hex(await hmac(await signingKey(secretKey, date), toSign));
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return `${origin}${path}?${canonicalQuery(query)}`;
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}
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