fix(auth): hash stored api keys

src/utils/api-key.ts

@@ -0,0 +1,36 @@
+const API_KEY_HASH_PREFIX = 'sha256:';
+
+export function constantTimeEquals(a: string, b: string): boolean {
+  const encA = new TextEncoder().encode(a);
+  const encB = new TextEncoder().encode(b);
+  if (encA.length !== encB.length) return false;
+
+  let diff = 0;
+  for (let i = 0; i < encA.length; i++) {
+    diff |= encA[i] ^ encB[i];
+  }
+  return diff === 0;
+}
+
+function toHex(bytes: ArrayBuffer): string {
+  return [...new Uint8Array(bytes)]
+    .map((byte) => byte.toString(16).padStart(2, '0'))
+    .join('');
+}
+
+export function isStoredApiKeyHash(value: string | null | undefined): boolean {
+  return String(value || '').startsWith(API_KEY_HASH_PREFIX);
+}
+
+export async function hashApiKey(apiKey: string): Promise<string> {
+  const digest = await crypto.subtle.digest('SHA-256', new TextEncoder().encode(apiKey));
+  return `${API_KEY_HASH_PREFIX}${toHex(digest)}`;
+}
+
+export async function verifyApiKey(apiKey: string, storedApiKey: string | null | undefined): Promise<boolean> {
+  const stored = String(storedApiKey || '').trim();
+  if (!isStoredApiKeyHash(stored)) return false;
+
+  const hashed = await hashApiKey(apiKey);
+  return constantTimeEquals(hashed, stored);
+}