android-security-encryptionlisted

# Android Security and Encryption ## Core Principles - Encrypt sensitive local data only when the threat model justifies it. - Keep secrets out of source control and out of logs. - Minimize what is stored locally in the first place. - Prefer platform-backed security primitives over custom crypto. - Security decisions should be explicit and documented, not accidental. --- ## What Usually Needs Protection Typical sensitive data: - auth/session secrets - refresh tokens - locally cached private user data when risk is meaningful - API credentials used only for local dev tooling, not production runtime - cryptographic keys and encrypted file metadata Usually not worth heavy encryption by itself: - theme settings - sort order - onboarding flags - non-sensitive feature toggles See the **android-datastore-preferences** and **android-auth-security** skills for adjacent storage guidance. --- ## Use Platform Security First Prefer: - Android Keystore for key management - platform biometric/device credential prompts for local unlock - vetted libraries/APIs for encrypted storage Avoid: - inventing custom encryption schemes - hardcoding keys in app code - storing raw secrets unencrypted in SharedPreferences or plain files --- ## Keystore Boundary The Keystore should manage keys, not your whole app architecture. Good pattern: - generate/store a key alias in Keystore - use it to wrap or protect local sensitive values - keep higher-level repositories unaware of crypto details whe