cipher/src/routes/backup.js

// Encrypted recovery backup + QR provisioning relay. The server stores and
// relays ONLY ciphertext — it can never read the keys passing through here.

import { Hono } from "hono";
import { requireAuth } from "../lib/auth.js";
import { now, randomToken } from "../lib/util.js";

const app = new Hono();

const PROVISION_TTL = 1000 * 60 * 10; // 10 minutes

// ---- recovery backup (decryptable only with the user's recovery code) ----

// POST /api/backup  body: { payload: {salt, iv, ct} }
app.post("/backup", requireAuth(), async (c) => {
  const userId = c.get("userId");
  const body = await c.req.json().catch(() => null);
  if (!body?.payload) return c.json({ error: "missing payload" }, 400);
  await c.env.DB.prepare(
    `INSERT INTO key_backups (user_id, payload, updated_at) VALUES (?,?,?)
     ON CONFLICT(user_id) DO UPDATE SET payload=excluded.payload, updated_at=excluded.updated_at`
  )
    .bind(userId, JSON.stringify(body.payload), now())
    .run();
  return c.json({ ok: true });
});

// GET /api/backup  -> { payload } | 404
app.get("/backup", requireAuth(), async (c) => {
  const userId = c.get("userId");
  const row = await c.env.DB.prepare("SELECT payload FROM key_backups WHERE user_id = ?")
    .bind(userId)
    .first();
  if (!row) return c.json({ error: "no backup" }, 404);
  return c.json({ payload: JSON.parse(row.payload) });
});

// GET /api/backup/exists  -> { exists } (used by login to offer restore)
app.get("/backup/exists", requireAuth(), async (c) => {
  const userId = c.get("userId");
  const row = await c.env.DB.prepare("SELECT 1 AS x FROM key_backups WHERE user_id = ?")
    .bind(userId)
    .first();
  return c.json({ exists: !!row });
});

// ---- QR provisioning relay ----

// POST /api/provision/new  body: { ephemeralPub }  (UNAUTH — new device has no account yet)
app.post("/provision/new", async (c) => {
  const body = await c.req.json().catch(() => null);
  if (!body?.ephemeralPub) return c.json({ error: "missing ephemeralPub" }, 400);
  const id = randomToken(18);
  await c.env.DB.prepare(
    "INSERT INTO provisions (id, ephemeral_pub, created_at) VALUES (?,?,?)"
  )
    .bind(id, body.ephemeralPub, now())
    .run();
  return c.json({ provisionId: id });
});

// GET /api/provision/:id  (UNAUTH — id is the capability) -> { ephemeralPub, payload|null }
app.get("/provision/:id", async (c) => {
  const id = c.req.param("id");
  const row = await c.env.DB.prepare(
    "SELECT ephemeral_pub, payload, created_at FROM provisions WHERE id = ?"
  )
    .bind(id)
    .first();
  if (!row) return c.json({ error: "not found" }, 404);
  if (row.created_at + PROVISION_TTL < now()) return c.json({ error: "expired" }, 410);
  return c.json({
    ephemeralPub: row.ephemeral_pub,
    payload: row.payload ? JSON.parse(row.payload) : null,
  });
});

// POST /api/provision/:id/complete  (AUTH) body: { payload }
// The authorizing device drops the blob it encrypted to the new device's key.
app.post("/provision/:id/complete", requireAuth(), async (c) => {
  const id = c.req.param("id");
  const body = await c.req.json().catch(() => null);
  if (!body?.payload) return c.json({ error: "missing payload" }, 400);
  const row = await c.env.DB.prepare("SELECT created_at FROM provisions WHERE id = ?")
    .bind(id)
    .first();
  if (!row) return c.json({ error: "not found" }, 404);
  if (row.created_at + PROVISION_TTL < now()) return c.json({ error: "expired" }, 410);
  await c.env.DB.prepare("UPDATE provisions SET payload=?, claimed_at=? WHERE id=?")
    .bind(JSON.stringify(body.payload), now(), id)
    .run();
  return c.json({ ok: true });
});

export default app;