Mobile Security

Skill — Mobile Security Architecture

When this skill activates

This skill activates when implementing security-sensitive mobile features, including certificate pinning, secure storage, biometric authentication, root/jailbreak detection, or protecting against mobile-specific attack vectors.

Mandatory actions when this skill is active

Before writing any code

1. Review OWASP Mobile Top 10 and identify applicable threats to the application
2. Determine data classification and storage requirements (keychain/keystore for sensitive data, never UserDefaults/SharedPreferences)
3. Establish certificate pinning strategy (pin leaf certificate, intermediate, or public key hash)
4. Plan authentication flow with biometric fallback, token refresh, and secure token storage

During implementation

• Store sensitive data in platform secure storage (iOS Keychain with proper accessibility attributes, Android Keystore)
• Implement certificate pinning for API communications to prevent man-in-the-middle attacks
• Use biometric authentication (Face ID, Touch ID, Biometric Prompt) with proper fallback to passcode
• Implement root/jailbreak detection (check for common indicators, but never rely solely on client-side checks)
• Encrypt local databases and sensitive files using platform encryption APIs (SQLCipher, native encryption)
• Obfuscate code (ProGuard/R8 for Android, native code for critical logic) to deter reverse engineering
• Implement proper session management with token expiration, refresh tokens, and secure logout

After implementation

• Test security implementation with security scanning tools (MobSF, QARK, or commercial tools)
• Verify certificate pinning works correctly and fails on MITM attempts
• Test biometric authentication edge cases: disabled biometrics, changed biometrics, hardware unavailability
• Validate secure storage: data persists securely across app restarts, inaccessible without authentication
• Test root/jailbreak detection on compromised devices, verify graceful degradation or blocking

Self-check before task completion

• Sensitive data is never stored in plaintext (logs, UserDefaults, SharedPreferences, temp files)
• Certificate pinning is implemented for all API endpoints with sensitive data
• Biometric authentication follows platform best practices (keychain/keystore-backed, proper error handling)
• Root/jailbreak detection is implemented with appropriate response (warn, degrade functionality, or block)
• API tokens are stored securely (keychain/keystore) and transmitted securely (HTTPS only, proper headers)
• App handles security failures gracefully (logout on tampering detection, clear sensitive data on uninstall)