Strong encryption is only as safe as its key. A key hard-coded in the binary or kept in a preferences file can be extracted from any copy of the app, which defeats every protection that depends on it.
- Generate keys inside the Secure Enclave or Android Keystore and make them non-exportable.
- Never hard-code keys or secrets in the app; anything shipped in the binary is public.
- Bind high-value keys to user authentication where the feature needs it, and plan for invalidation when biometrics change.
MASTG tests in the local projects
Neither local project runs a MASTG test for MASVS-CRYPTO-2. The guides below explain the platform mechanisms, and the control’s page on mas.owasp.org links the MASTG tests and weaknesses OWASP maps to it.
Guides on this site
Harden an iOS app's storage, network and entry points
Store secrets in the Keychain with the narrowest accessibility class, set file protection explicitly, keep App Transport Security on, prefer universal links, constrain WKWebView bridges, keep step-up keys in the Secure Enclave, verify App Attest on the server and ship an accurate privacy manifest, mapped to OWASP MASVS 2.1.
Harden an Android app's storage, network and entry points
Encrypt local secrets with Android Keystore keys now that Jetpack Security is deprecated, set transport policy in Network Security Configuration, close exported components and mutable PendingIntents, confine WebViews, verify App Links and judge Play Integrity verdicts on the server, mapped to OWASP MASVS 2.1.
Practice
- Keep an iOS app's storage, links and web bridge in bounds · Local project
- Repair an Android app's links, components, network policy and storage · Local project
References
List data from the publisher. A guide is listed as the main subject when the weakness or risk is what the guide is about, and as covering it when a dedicated section or worked example addresses it.
Control statements are quoted from OWASP MASVS v2.1.0, licensed CC BY-SA 4.0; the rest is this site's summary. MASTG tests are those the iOS and Android projects here run, with their titles from mas.owasp.org. License.