Day 122: API Security — Key Management, Request Signing, IP Whitelisting, Scanning & Threat Protection
What we’re building today?
A production-grade API Security layer with five interlocking defenses —
(1) API key lifecycle management,
(2) HMAC request signing,
(3) IP whitelisting with CIDR support,
(4) regex-based payload scanning for injection attacks, and
(5) a threat-score engine with auto-suspension. The whole thing is wired into a React dashboard that looks and feels like AWS API Gateway crossed with Datadog’s security console.
Where This Fits
You built rate limiting yesterday (Day 121). That stops abuse by volume. Today you’re handling identity and payload integrity — two completely different threat surfaces. The security layer sits as FastAPI middleware, meaning it intercepts every request before your application code ever runs. Next up, Day 123 wraps the whole API with OpenAPI documentation and SDK generation.
The five components today form a pipeline: each stage can either pass the request forward or terminate it with a 4xx. Every decision gets logged to a security_events table, giving you a full audit trail for compliance and forensics.
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