6225e79d9b
Files in your own Sia account can now be shared with anyone through a navigate.st/sia link that keeps working with this computer off; the navigate.st service is live, so the buttons can ship.
107 lines
5.8 KiB
JavaScript
107 lines
5.8 KiB
JavaScript
// Sia share links for files in your own Sia account. A shared object URL lets
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// anyone read ONE object (its data key travels in the URL fragment) and
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// nothing else in the account. It is made the way the Sia SDK makes it
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// (siastorage CreateSharedObjectURL, indexd api/app/client.go):
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// 1. s3d's database maps <drive>/<name> to the object's Sia id;
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// 2. the indexer returns the sealed object (signed GET /objects/<id>);
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// 3. its data key is opened with a key derived from s3d's app key:
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// XChaCha20-Poly1305 under HKDF-BLAKE2b-256(appKey, salt = id, "dataKey");
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// 4. the link is a signed GET /objects/<id>/shared, valid until a date,
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// with #encryption_key=<data key> (padded URL-safe base64).
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// The app key is read from s3d's database for this and never leaves.
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import crypto from 'node:crypto';
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import fs from 'node:fs';
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import path from 'node:path';
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import { blake2b256 } from './blake2b.js';
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import { readConnection, signRequest } from './sia-account.js';
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// ---- HMAC / HKDF over BLAKE2b-256 (block size 128) --------------------------------
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export function hmacBlake2b256(key, data) {
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let k = Buffer.from(key);
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if (k.length > 128) k = blake2b256(k);
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const block = Buffer.alloc(128);
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k.copy(block);
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const ipad = Buffer.from(block.map((b) => b ^ 0x36));
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const opad = Buffer.from(block.map((b) => b ^ 0x5c));
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return blake2b256(Buffer.concat([opad, blake2b256(Buffer.concat([ipad, Buffer.from(data)]))]));
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}
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export function hkdfBlake2b256(ikm, salt, info, length) {
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const prk = hmacBlake2b256(salt && salt.length ? salt : Buffer.alloc(32), ikm);
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const out = [];
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let t = Buffer.alloc(0);
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for (let i = 1; Buffer.concat(out).length < length; i++) {
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t = hmacBlake2b256(prk, Buffer.concat([t, Buffer.from(info || []), Buffer.from([i])]));
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out.push(t);
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}
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return Buffer.concat(out).subarray(0, length);
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}
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// ---- XChaCha20-Poly1305 (open only) ------------------------------------------------
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const rotl = (v, n) => ((v << n) | (v >>> (32 - n))) >>> 0;
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function quarter(s, a, b, c, d) {
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s[a] = (s[a] + s[b]) >>> 0; s[d] = rotl(s[d] ^ s[a], 16);
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s[c] = (s[c] + s[d]) >>> 0; s[b] = rotl(s[b] ^ s[c], 12);
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s[a] = (s[a] + s[b]) >>> 0; s[d] = rotl(s[d] ^ s[a], 8);
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s[c] = (s[c] + s[d]) >>> 0; s[b] = rotl(s[b] ^ s[c], 7);
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}
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export function hchacha20(key, nonce16) {
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const s = new Uint32Array(16);
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s.set([0x61707865, 0x3320646e, 0x79622d32, 0x6b206574]);
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for (let i = 0; i < 8; i++) s[4 + i] = key.readUInt32LE(i * 4);
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for (let i = 0; i < 4; i++) s[12 + i] = nonce16.readUInt32LE(i * 4);
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for (let r = 0; r < 10; r++) {
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quarter(s, 0, 4, 8, 12); quarter(s, 1, 5, 9, 13); quarter(s, 2, 6, 10, 14); quarter(s, 3, 7, 11, 15);
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quarter(s, 0, 5, 10, 15); quarter(s, 1, 6, 11, 12); quarter(s, 2, 7, 8, 13); quarter(s, 3, 4, 9, 14);
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}
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const out = Buffer.alloc(32);
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[0, 1, 2, 3, 12, 13, 14, 15].forEach((w, i) => out.writeUInt32LE(s[w], i * 4));
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return out;
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}
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export function xchachaOpen(key, nonce24, sealed) {
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const sub = hchacha20(Buffer.from(key), Buffer.from(nonce24).subarray(0, 16));
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const nonce12 = Buffer.concat([Buffer.alloc(4), Buffer.from(nonce24).subarray(16, 24)]);
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const ct = Buffer.from(sealed);
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const d = crypto.createDecipheriv('chacha20-poly1305', sub, nonce12, { authTagLength: 16 });
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d.setAuthTag(ct.subarray(ct.length - 16));
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return Buffer.concat([d.update(ct.subarray(0, ct.length - 16)), d.final()]);
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}
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// ---- s3d's database: <drive>/<name> -> Sia object id -------------------------------
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export async function siaObjectId(dataDir, bucket, key) {
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const file = path.join(dataDir, 's3d.db');
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if (!fs.existsSync(file)) throw new Error('s3d has no database yet');
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const { DatabaseSync } = await import('node:sqlite');
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const db = new DatabaseSync(file, { readOnly: true });
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try {
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const row = db.prepare(`SELECT o.sia_object_id AS id, o.size AS size FROM objects o JOIN buckets b ON b.id = o.bucket_id
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WHERE b.name = ? AND o.name = ? AND o.is_latest = 1 AND o.is_delete_marker = 0`).get(bucket, key);
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if (!row) return null;
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return { id: row.id ? Buffer.from(row.id) : null, size: Number(row.size) };
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} finally { db.close(); }
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}
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const b64urlPadded = (b) => Buffer.from(b).toString('base64').replace(/\+/g, '-').replace(/\//g, '_');
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// The shared-object URL for one file, valid until validUntil (unix seconds).
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export async function createShareUrl(dataDir, bucket, key, validUntil, { fetchImpl = fetch } = {}) {
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const conn = await readConnection(dataDir);
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if (!conn?.appKey || !conn.indexerUrl) throw Object.assign(new Error('s3d is not connected to a Sia account'), { status: 409 });
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const obj = await siaObjectId(dataDir, bucket, key);
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if (!obj) throw Object.assign(new Error('no such file'), { status: 404 });
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if (!obj.id) throw Object.assign(new Error('This file has not reached Sia yet. Upload it now (Overview › Upload now) and try again.'), { status: 409, code: 'pending' });
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const base = conn.indexerUrl.replace(/\/+$/, '');
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const idHex = obj.id.toString('hex');
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const res = await fetchImpl(signRequest(conn.appKey, 'GET', `${base}/objects/${idHex}`, Math.floor(Date.now() / 1000) + 120), { headers: { accept: 'application/json' }, signal: AbortSignal.timeout(20_000) });
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if (!res.ok) throw new Error(`indexer answered ${res.status}: ${(await res.text()).slice(0, 160)}`);
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const sealed = await res.json();
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const enc = Buffer.from(sealed.encryptedDataKey || '', 'base64');
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if (enc.length < 24 + 16) throw new Error('the indexer returned no data key');
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const kek = hkdfBlake2b256(conn.appKey, obj.id, Buffer.from('dataKey'), 32);
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const dataKey = xchachaOpen(kek, enc.subarray(0, 24), enc.subarray(24));
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kek.fill(0);
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const u = signRequest(conn.appKey, 'GET', `${base}/objects/${idHex}/shared`, validUntil);
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u.hash = `encryption_key=${b64urlPadded(dataKey)}`;
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dataKey.fill(0);
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return { url: u.toString(), size: obj.size, objectId: idHex };
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}
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