Why Mobile Apps Need Built-In Attestation Security: Beyond API Tokens

In mobile development, user experience often takes center stage - but if you're building apps that talk to the cloud, mobile API security should be baked in, not bolted on. Traditional approaches like API tokens may seem fine until your backend gets flooded with fake requests from cloned apps, bots, or emulators.

This post is for developers who want to understand the real security threats facing mobile apps today, and how built-in attestation - like Play Integrity API (Android) and App Attestation (iOS) - can make your backend bot-resistant by default.

We’ll also show how native attestation supports mobile API security best practices by ensuring backend access is verified and cryptographically trusted.

The hidden threat: fake apps and abuse

Most mobile apps embed credentials - like API keys or client secrets - into their code. But anyone with a decompiler can reverse-engineer these and use them to impersonate your app.

Once attackers have those credentials, they can:

• Emulate app behavior in emulators or scripts
• Abuse free-tier API access
• Flood sign-up or referral systems
• Scrape or automate usage at scale

This is why mobile API security is essential in any modern mobile stack.

Real-world abuse scenarios:

Gaming app abuse

A reward-based game offers in-app currency for completing challenges. Bots reverse-engineer the API and simulate gameplay in emulators - flooding the backend and inflating resource usage and costs.

Fintech app fraud

An early-stage fintech app offers referral bonuses. Attackers clone the APK and run automated scripts from thousands of fake devices to exploit the referral system.

SaaS app resource drain

A productivity tool with a generous free plan is targeted by fake signups using emulated apps. Thousands of phantom users are created to abuse backend API and storage services.

These issues are:

• Hard to detect (appear like real users)
• Expensive to fix (infrastructure scaling, fraud filtering)
• Damaging to your credibility and margins

Why API keys alone aren’t enough

API keys have been the default way to secure communication between a mobile app and its backend for years - but in a mobile-first, attacker-aware environment, they’re simply not built for the threats developers face today. As secure mobile APIs become more critical, relying only on static keys creates serious risk.

Here’s why they fall short:

1. API keys are static and hardcoded

Most developers embed the API key into the app binary, either through configuration files, environment variables at build time, or within the codebase itself. But once your app is live, anyone can download the binary, reverse-engineer it, and extract the key. Tools like JADX, ApkTool, or even simple string extraction scripts make this a trivial task.

Even obfuscation or code encryption only slows down determined attackers. And once a key is out in the wild, it can be:

• Shared across communities
• Integrated into scripts or emulators
• Reused for automated abuse at scale

If your API key is acting like a password to your backend, imagine giving every user the same password. That’s what hardcoded API keys are. This is why mobile API security needs to go beyond traditional keys.

2. API keys don’t know who’s using them

API tokens can confirm something is making a request - but not what or who. There’s no way to verify:

• Whether the request comes from your real, unmodified mobile app
• Whether the app is running on a legitimate, physical device
• Whether the environment has been compromised (e.g., rooted, jailbroken)

This opens the door to abuse from:

• Cloned or tampered app versions
• Emulators running automated bot scripts
• Man-in-the-middle proxies injecting or replaying requests

In short, API keys don't provide context - they're a weak signal of authenticity.

3. Rotating keys at scale is operationally risky

Once a key is compromised, you’ll need to:

• Push out an app update with a new key
• Invalidate the old key on the backend
• Hope users update quickly enough to avoid disruption

This is fine in low-usage dev environments, but at scale it introduces:

• Downtime for users on older versions
• Friction for app store approvals and update adoption
• Chaos if you need to rotate multiple keys across apps or platforms

For fast-moving teams, key rotation can become a painful bottleneck or a security liability when deferred. To truly implement your mobile-to-api security, dynamic, attested mechanisms are now preferred.

4. Keys can be shared, replayed, or emulated

Let’s say an attacker extracts your API key. They can now:

• Replay legitimate requests from a tampered device
• Build their own app using your API
• Create scripts to automate or abuse any open endpoints

Your backend will have no way of distinguishing between a legitimate request and a malicious one. That’s why real mobile API security needs to be runtime-aware.

5. Security is not context-aware without attestation

Modern mobile security requires runtime context:

• What device is the app running on?
• Was the app downloaded from a legitimate store?
• Is the OS compromised?
• Has the app binary been tampered with?

None of this is available with plain API key usage. That’s why attestation matters - it forms the components of mobile API security that enable real-time verification.

Attestation tokens are:

• Cryptographically signed by Google or Apple
• Bound to the device, app binary, and app store installation
• Short-lived and unique per session

6. APIs need fine-grained, dynamic access control

Static credentials (like API keys) can't:

• Differentiate between app sessions
• Apply device-level limits or rate controls
• Identify behavioral anomalies across devices

In contrast, using attestation + ephemeral tokens (like JWTs):

• Lets you bind backend access to specific sessions on specific devices
• Enables per-device limits and analytics
• Helps filter or flag traffic from weak integrity scores or failed attestation

This is the foundation of secure API access in mobile apps - where access is granted not just by who you are, but by proving how, where, and what you're running.

Security Method Comparison

A modern alternative: mobile app attestation

Enter Play Integrity API (Android) and App Attestation (iOS). These platform-native technologies allow your backend to verify:

• The app is authentic (not modified or fake)
• It’s running on a genuine physical device (not an emulator)
• The device is in a safe, non-compromised state

These tools are now core to integrating mobile apps with secured APIs, providing trusted signals directly from the OS vendor.

Attestation is cryptographic. It’s extremely difficult to forge, and it allows your backend to reject traffic that doesn't come from your real, untampered app.

Android: Play Integrity API

Goal: Verify your app is unmodified and running on a genuine, secure Android device.

How it works:

1. Your app requests an integrity token via Google Play services
2. Google checks:
   • Was it installed from Play Store?
   • Is the device rooted or an emulator?
   • Has the APK been tampered with?
3. Google replies with a signed response:
   • App integrity: PLAY_STORE, UNRECOGNIZED_VERSION, etc.
   • Device integrity: MEETS_DEVICE_INTEGRITY, MEETS_BASIC_INTEGRITY, etc.
   • Licensing info
4. Your app or backend verifies the signature using Google’s public key
5. You decide how to treat the request (allow/deny/flag)

Requires Google Play Services - won’t work on Huawei or AOSP-only devices

iOS: App Attestation (via App Attest or DeviceCheck)

Goal: Ensure your iOS app is running on a genuine Apple device and hasn’t been tampered with.

How it works:

1. App creates a key via Apple’s Secure Enclave on install
2. App asks Apple: “Prove this key came from a real Apple device, installed via App Store.”
3. Apple sends an attestation:
   • Binds the key to your app's bundle ID
   • Confirms the device is real and secure
4. Your backend verifies the attestation with Apple
5. Future requests can be signed with this key to verify the app on every session

This is enforced in hardware, not just software, and can detect jailbreaks or sideloaded apps

How calljmp builds this in

We built Calljmp with mobile security as a first-class citizen:

• No API keys to leak
• Automatic attestation for Android and iOS
• Short-lived JWTs issued only after attestation
• Tokens tied to app + device + user
• Everything handled by Calljmp’s infrastructure - no extra code needed

Whether you’re building with Flutter or React Native, Calljmp does the heavy lifting behind the scenes to implement your mobile-to-api security standards effectively.

Why developers should care

• Protect infrastructure from being overwhelmed by fake traffic
• Prevent abuse before it hits your database or logic
• Skip API key headaches (rotation, leakage, invalidation)
• Ship secure mobile apps faster, with less custom backend code

TL;DR for Developers

Stop relying solely on API keys - they don’t know who is making the request. Platform attestation gives you proof that a request comes from your real app on a real device.

Calljmp offers this out of the box. No keys. No manual setup. Just mobile API security built in.