fix: add timeSafe checks for signed tokens and api keys

Author: MohamedBassem

packages/shared/signedTokens.test.ts

@@ -61,7 +61,19 @@ describe("signed tokens", () => {
     const decoded: SignedTokenPayload = JSON.parse(
       Buffer.from(token, "base64").toString(),
     );
-    decoded.signature = "tampered" + decoded.signature;
+    decoded.signature = `${decoded.signature[0] === "0" ? "1" : "0"}${decoded.signature.slice(1)}`;
+    const tampered = Buffer.from(JSON.stringify(decoded)).toString("base64");
+    const verified = verifySignedToken(tampered, SECRET, testSchema);
+    expect(verified).toBeNull();
+  });
+
+  it("should return null for a malformed signature", () => {
+    const token = createSignedToken(testPayload, SECRET);
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+    const decoded: SignedTokenPayload = JSON.parse(
+      Buffer.from(token, "base64").toString(),
+    );
+    decoded.signature = "not-a-hex-signature";
     const tampered = Buffer.from(JSON.stringify(decoded)).toString("base64");
     const verified = verifySignedToken(tampered, SECRET, testSchema);
     expect(verified).toBeNull();

packages/shared/signedTokens.ts

@@ -88,9 +88,13 @@ export function verifySignedToken<T>(
     const expectedSignature = crypto
       .createHmac("sha256", secret)
       .update(JSON.stringify(payload))
-      .digest("hex");
+      .digest();
+    const actualSignature = Buffer.from(signature, "hex");
 
-    if (signature !== expectedSignature) {
+    if (
+      actualSignature.length !== expectedSignature.length ||
+      !crypto.timingSafeEqual(actualSignature, expectedSignature)
+    ) {
       return null;
     }
     // Check expiry

packages/trpc/auth.ts

@@ -1,4 +1,4 @@
-import { createHash, randomBytes } from "crypto";
+import { createHash, randomBytes, timingSafeEqual } from "node:crypto";
 import * as bcrypt from "bcryptjs";
 import { and, eq } from "drizzle-orm";
 
@@ -124,10 +124,14 @@ export async function authenticateApiKey(key: string, database: Context["db"]) {
     case 1:
       validation = await bcrypt.compare(keySecret, hash);
       break;
-    case 2:
+    case 2: {
+      const candidateHash = createHash("sha256").update(keySecret).digest();
+      const expectedHash = Buffer.from(hash, "base64");
       validation =
-        createHash("sha256").update(keySecret).digest("base64") == hash;
+        candidateHash.length === expectedHash.length &&
+        timingSafeEqual(candidateHash, expectedHash);
       break;
+    }
     default:
       throw new Error("Invalid API Key");
   }