# Encryption Specification for Health Tracker

## Overview
This document provides a detailed specification for implementing encryption in the Health Tracker app to ensure user data privacy and security.

## Key Management
- **Key Pair Generation**: Users generate RSA key pairs upon app installation.
- **Public Key**: Utilized for encrypting data, stored securely within the app.
- **Private Key**: Stored locally on the user's device, protected by a symmetric encryption key that can be unlocked via biometric authentication or password.

## Data Encryption Process
1. **Symmetric Encryption**: Encrypts user data (e.g., AES encryption).
2. **Asymmetric Encryption**: Encrypts the symmetric key using the user's RSA public key for secure storage and transfer.

## Biometric and Password Authentication
- Utilize platform-specific biometrics for unlocking the encrypted private key.
- Provide password fallback for situations where biometric authentication is unavailable.

## Encrypted Cloud Backups
- **Premium Feature**: Only available to users who purchase through in-app upgrades.
- **End-to-End Encryption**: Ensures user data is encrypted before transmission, remaining secure during cloud storage.
- **Cloud Storage Integration**: Integrates with platforms like AWS S3 or Google Cloud, supporting API calls for secure backup management.
