Import source: backend/src/lib/password

Import the existing local project snapshot. This commit organizes existing files; it does not represent newly developed functionality.

backend/src/lib/password.ts

@@ -0,0 +1,18 @@
+import { randomBytes, scryptSync, timingSafeEqual } from "crypto";
+
+const keyLength = 64;
+
+export function hashPassword(password: string) {
+  const salt = randomBytes(24).toString("hex");
+  const hash = scryptSync(password, salt, keyLength).toString("hex");
+  return `scrypt$${salt}$${hash}`;
+}
+
+export function verifyPassword(password: string, storedHash: string | null | undefined) {
+  if (!storedHash) return false;
+  const [algorithm, salt, hash] = storedHash.split("$");
+  if (algorithm !== "scrypt" || !salt || !hash) return false;
+  const expected = Buffer.from(hash, "hex");
+  const actual = scryptSync(password, salt, expected.length);
+  return expected.length === actual.length && timingSafeEqual(expected, actual);
+}