Epsilon Integrity

#Features

• Single API: One DeviceIntegrityCheck entry point on every target.
• Android Play Integrity: Requests a Play Integrity token and retries transient Play errors with the same nonce.
• iOS App Attest: Creates a hardware-backed key, stores its identifier in the Keychain, attests it, and later produces assertions.
• Structured result: Success and failure are both represented by IntegrityCheckResult.

#Supported Platforms

• Android
• iOS

#Key Components

#DeviceIntegrityCheck

Construct it with a CommonContext from epsilon-core. On Android that type is android.content.Context. On iOS, JVM, and JavaScript, pass the stub Context object from ag.sportradar.mobile.epsilon.context.

getIntegrityToken calls nonceProvider once and embeds that nonce in the attestation. Fetch the nonce from your backend inside the lambda. Coroutine cancellation is propagated to the caller. Any other failure from the nonce provider, or from the platform attestation call, is returned as IntegrityCheckResult.error.

#IntegrityCheckResult

On Android and iOS, a finished check sets one of these properties. On JVM and JavaScript, both stay null after a successful nonce fetch.

#Platform behavior

#Android

The Android implementation calls the Play Integrity API with the nonce and returns the Play Integrity token.

• Each Play request times out after 60 seconds.
• Transient failures are retried up to 3 times.
• Delays are 5 seconds, then 10 seconds, then 20 seconds.

Retried Play error codes are network failure, too many requests, Google server unavailable, client transient error, and internal error. Other Play errors are returned immediately in IntegrityCheckResult.error.

Link the app to Play Integrity in the Play Console. This module sends only the nonce. Play resolves the cloud project from that app linking.

#iOS

The iOS implementation uses DCAppAttestService. The nonce string is SHA-256 hashed before it is passed to App Attest. The returned token is the Base64-encoded attestation object or assertion.

Lifecycle:

1. The first successful call generates a key, stores its key ID in the Keychain, attests the key with Apple, and returns the attestation object.
2. Later calls generate an assertion with the stored key.
3. When Apple reports the stored key as invalid, the key ID is removed and a new key is created and attested.

#JVM and JavaScript

These targets call nonceProvider and then return IntegrityCheckResult() with token and error both null.

#Usage

Add the dependency to your commonMain:

#Dependency on Core

This module depends on epsilon-core and exports it, so CommonContext is available when you include integrity.