APIs & Security Best Practices

The Rust security baseline for HTTP APIs - auth, validation, secrets, dependencies, and operability.

How to Use This List

Run through before shipping a new public endpoint or integration.
Map each rule to CI checks where possible (cargo audit, tests, linters).
Review after security incidents and dependency upgrades.

A - API Design

Stable error envelope with machine-readable code. Same JSON shape for all 4xx/5xx.
Version public APIs explicitly. /v1 prefix or Accept header contract.
Document status codes and idempotency rules. POST payments require Idempotency-Key.
Paginate collections; cap limit. Prevent unbounded DB reads.
Separate public and admin routers. Different auth and rate limits.

B - Authentication & Authorization

Authenticate every protected route. Middleware or extractor - no forgotten endpoints.
Short-lived access tokens; rotate refresh tokens. JWT exp validated with leeway.
Store passwords with argon2id. Never SHA-256 alone.
Authorize per resource, not only per route. User A cannot read User B by ID guessing.
Return 401 vs 403 correctly. Missing auth vs insufficient permission.

C - Input & Data

Validate at HTTP boundary. Serde + validator before DB.
Parameterized SQL only. No format! for query values.
Limit request body size. Tower RequestBodyLimitLayer.
Verify webhook signatures. HMAC before processing payload.
GraphQL depth/complexity limits. If GraphQL is exposed.

D - Secrets & Crypto

Secrets from env/vault, never in git. Use secrecy types in config.
TLS everywhere in production. rustls or edge termination documented.
Rotate keys with overlap window. JWT JWKS support multiple keys.
Use vetted crypto crates. ring/RustCrypto - no custom ciphers.
Redact Authorization and cookies in logs.

E - Abuse & Supply Chain

Rate limit login and expensive endpoints. Redis counters when multi-instance.
Run cargo audit and cargo deny in CI. Fail on critical advisories.
Commit Cargo.lock for applications. Reproducible builds.
Vet new dependencies in PR. cargo vet or security review checklist.
Security headers on HTTP responses. CSP, X-Content-Type-Options, frame-ancestors.

FAQs

Top production security mistake?

Missing auth on a new route and logging secrets in debug traces.

Rust memory safety enough?

No - logic flaws, injection, and auth bugs still happen.

Minimum auth stack?

argon2 passwords or OIDC + JWT validation + HTTPS + rate limits.

OpenAPI public?

Disable or protect in production; exposes attack surface map.

Penetration test cadence?

Annually or before major public launch; fix findings by severity.

SBOM required?

Increasingly for enterprise customers - cargo cyclonedx.

unsafe code?

Isolate in audited crate; #![forbid(unsafe_code)] in API binary if policy allows.

GDPR delete?

Document data map; cascade delete tokens, cache keys, and backups policy.

Security champions?

One owner reviews security-sensitive PRs weekly.

Incident runbook?

Revoke tokens, rotate secrets, enable enhanced logging, notify customers per policy.

API Design Basics - REST conventions
JWT & OAuth2 - Token flows
Input Validation & Injection - Attack defenses
Supply-Chain Security - Dependency audit
Web Backends Best Practices - HTTP service rules

Stack versions: This page was written for Rust 1.97.0 (edition 2024), Tokio 1.x, Axum 0.8, serde 1.0, sqlx 0.8, clap 4, and Polars 0.46+.

APIs & Security Best Practices

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APIs & Security Best Practices