Security Cheat Sheet

Need X → use Y. Each row opens the lesson that explains the trust boundary, failure mode, defense layers and residual risk behind the shortcut.

Identity

Need identity→Authentication Need a permission decision→Authorization Need browser login state→Session + secure cookie Need delegated API access→OAuth Need login federation→OIDC Need password storage→Dedicated password hashing

Cryptography

Need confidential transport→TLS

Application

User data enters HTML→Context-aware output encoding User data enters SQL→Parameterized query Backend fetches a user URL→SSRF destination + egress controls Receive an external webhook→Signature + replay protection

Architecture

Protect a privileged service→Least privilege + authorization Prevent cross-tenant access→Tenant-aware authorization everywhere

Infrastructure

Store a sensitive secret→Secret manager + scoped identity

Delivery

Reduce supply-chain risk→Dependency + build + CI controls

AI / Agents

Allow a high-risk agent action→Policy + approval + audit