Secure the Link: Network Security for Mobile App Developers

Chosen theme: Network Security for Mobile App Developers. Build apps your users can trust with practical, actionable guidance that keeps data safe across hostile networks, real devices, and fast-moving release cycles—without slowing your team down.

Designing a Secure Network Architecture

Authenticate every call, authorize every action, and never trust device state alone. Segment backend services, apply least privilege, and assume token compromise. Comment with your architectural wins and hiccups for others to learn from.

Protecting Data in Transit

Enforce TLS 1.2 or 1.3, disable obsolete ciphers, and verify hostnames. Prefer modern suites with perfect forward secrecy. On Android, set usesCleartextTraffic=false; on iOS, configure App Transport Security to require secure connections.

Protecting Data in Transit

Pin public keys rather than full certificates, keep backup pins, and deliver updates via remote config. Allow safer debugging only in non-production builds. Log pin failures to detect broad interception attempts early and accurately.

OAuth 2.0 with PKCE for Public Clients

Use PKCE for code exchange, avoid embedded client secrets, and prefer system browser sessions over webviews. On iOS, use ASWebAuthenticationSession; on Android, use browser-based flows to reduce phishing and cookie juggling risks.

Token Storage, Rotation, and Device Binding

Store tokens in Keychain or Android Keystore, never in plain preferences. Use short-lived access tokens, rotate refresh tokens, and consider proof-of-possession schemes like DPoP or attestation signals for sensitive, high-value operations.

Securing Redirects and Deep Links

Use claimed HTTPS links or Android App Links and iOS Universal Links to prevent hijacking. Validate redirect URIs strictly, and block custom schemes from being intercepted by untrusted applications on the device.

Safe HTTP Client Defaults

Set strict timeouts, sane retry budgets with jitter, and mandatory TLS verification. Centralize headers, user agents, and request signing. A single hardened client wrapper prevents dozens of subtle, risky per-call variations across the app.

Parsing and Input Validation at the Edge

Validate server responses rigorously, reject unexpected fields, and cap payload sizes. Favor safe JSON parsers, handle number ranges carefully, and sanitize error strings before logging to avoid accidentally persisting secrets or user identifiers.

Minimizing Sensitive Over-the-Wire Data

Send only what is required for the requested operation. Avoid verbose debug flags, remove PII from telemetry, and compress wisely without leaking content via side channels. Share your favorite redaction strategies with our community.

Testing, Monitoring, and Incident Response

Use mitmproxy or Charles to observe flows, and tools like Frida to probe pinning and hooking resilience. Document expected failures for unauthorized changes so testers and attackers hit the same, loud tripwires.