ThreadCount Community edition

Uniform stock management for healthcare linen rooms. Licensed under the GNU AGPL v3.

lib/ops/totp.ts

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+import { createCipheriv, createDecipheriv, createHash, randomBytes } from "crypto";
+import { totpVerify } from "../totp";
+
+/* An operator's second factor, stored under the console's own key.
+ *
+ * lib/totp.ts encrypts a coordinator's TOTP secret with a key derived from SESSION_SECRET, and
+ * that is the right blast radius there: rotating the product's secret invalidates customer
+ * sessions and customer second factors together. It is the wrong blast radius here. An
+ * operator's secret is kept under a key derived from OPS_SESSION_SECRET, so rotating either
+ * secret touches only its own side. The cipher, the format and the verification arithmetic are
+ * the product's own — nothing new is invented, only the key underneath it. */
+
+function key(): Buffer {
+  const s = process.env.OPS_SESSION_SECRET;
+  if (!s) throw new Error("OPS_SESSION_SECRET is required to store an operator's TOTP secret");
+  return createHash("sha256").update(`ops-totp:${s}`).digest();
+}
+
+export function encryptOpsSecret(plain: string): string {
+  const iv = randomBytes(12);
+  const c = createCipheriv("aes-256-gcm", key(), iv);
+  const enc = Buffer.concat([c.update(plain, "utf8"), c.final()]);
+  return `v1.${iv.toString("base64url")}.${c.getAuthTag().toString("base64url")}.${enc.toString("base64url")}`;
+}
+
+export function decryptOpsSecret(stored: string): string | null {
+  try {
+    const [v, iv, tag, enc] = stored.split(".");
+    if (v !== "v1") return null;
+    const d = createDecipheriv("aes-256-gcm", key(), Buffer.from(iv, "base64url"));
+    d.setAuthTag(Buffer.from(tag, "base64url"));
+    return Buffer.concat([d.update(Buffer.from(enc, "base64url")), d.final()]).toString("utf8");
+  } catch {
+    return null;
+  }
+}
+
+/** True only when the operator has a second factor enrolled AND the code matches it. */
+export function verifyOperatorCode(op: { totpSecret: string; totpEnabledAt: Date | null }, code: string): boolean {
+  if (!op.totpEnabledAt) return false;
+  const secret = decryptOpsSecret(op.totpSecret);
+  if (!secret) return false;
+  return totpVerify(secret, String(code || "").replace(/\s+/g, ""));
+}