• SQLite database is encrypted at rest using SQLCipher (AES-256).
• The encryption key is randomly generated on first boot and stored in the hardware-backed Keystore/Keychain via react-native-keychain.

• Zero Raw Photos: The system NEVER stores actual facial photographs. Instead, it extracts a 128-dimensional mathematical embedding (~512 bytes) from the face and discards the image immediately. A face cannot be reverse-engineered from this vector.

Every attendance record is cryptographically signed using a HMAC-SHA256 signature containing: WorkerID + GPS_Lat + GPS_Lng + UnixTimestamp + DeviceID If the user modifies the local database directly (e.g., changing the timestamp), the backend will detect a signature mismatch and flag the record as TAMPERED.

To preserve local storage space, all attendance logs and sync queues are aggressively purged after receiving an HTTP 200 OK from the AWS synchronization pipeline.