"Modern OAuth Security: OAuth 2.1, PAR, RAR, and DPoP for API Engineers"
If you build or secure APIs at scale, OAuth is no longer a checkbox protocol—it's a system of trust boundaries, browser realities, and failure modes that attackers actively exploit. This book is written for experienced API engineers, platform teams, and security-minded architects who need to reason precisely about OAuth in production: what to trust, what to bind, what to log, and what to reject. It focuses on modern deployments where correctness and operational discipline matter as much as RFC familiarity.
You'll master OAuth 2.1's security baseline and the threat model captured in current best practice, then implement the authorization code flow as the hardened "workhorse" with PKCE, strict redirect handling, and robust response binding. From there, you'll add Pushed Authorization Requests (PAR) to remove front-channel leakage and request tampering, model fine-grained permissions with Rich Authorization Requests (RAR), and mitigate token replay using DPoP sender-constrained access. The result is practical capability: designing flows, validating tokens, enforcing resource-server policy, debugging failures, and choosing mechanisms based on explicit risk and deployment constraints.
Assuming prior OAuth 2.0 exposure, the book differentiates itself by treating security as an engineering discipline: decision criteria, anti-pattern refactors, gateway enforcement, observability, and migration playbooks that keep real organizations safe while evolving clients and APIs.
