ThreadCount
1bc2de655a
Uniform stock management for healthcare linen rooms. Licensed under the GNU AGPL v3.
45 lines
1.8 KiB
TypeScript
45 lines
1.8 KiB
TypeScript
import { createHmac, timingSafeEqual } from "crypto";
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/* The short-lived ticket that carries "this password was correct" from the first step of sign-in
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* to the second.
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*
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* It is emphatically not a session: it grants nothing on its own, is only accepted by the
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* second-factor endpoint, and dies in five minutes. Keeping it stateless means a half-finished
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* sign-in leaves nothing behind to clean up, and there is no table for an attacker to fill.
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*
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* It carries the password version, so a password changed between the two steps invalidates the
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* ticket for exactly the same reason it invalidates a session.
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*/
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const TICKET_TTL_MS = 5 * 60 * 1000;
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function secret(): string {
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const s = process.env.SESSION_SECRET;
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if (!s) throw new Error("SESSION_SECRET is required");
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return s;
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}
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const b64 = (b: Buffer) => b.toString("base64url");
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const sign = (payload: string) => b64(createHmac("sha256", secret()).update(`2fa.${payload}`).digest());
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export function mintTicket(userId: string, pv: string): string {
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const payload = b64(Buffer.from(JSON.stringify({ uid: userId, pv, exp: Date.now() + TICKET_TTL_MS })));
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return `${payload}.${sign(payload)}`;
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}
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export function readTicket(ticket: string): { uid: string; pv: string } | null {
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const [payload, mac] = String(ticket || "").split(".");
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if (!payload || !mac) return null;
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const expect = sign(payload);
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const a = Buffer.from(mac, "utf8");
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const b = Buffer.from(expect, "utf8");
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if (a.length !== b.length || !timingSafeEqual(a, b)) return null;
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try {
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const t = JSON.parse(Buffer.from(payload, "base64url").toString("utf8")) as { uid?: string; pv?: string; exp?: number };
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if (!t.uid || !t.pv || !t.exp || t.exp < Date.now()) return null;
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return { uid: t.uid, pv: t.pv };
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} catch {
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return null;
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}
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}
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