Identity SDLC is the discipline of embedding identity and access control into every phase of the software development life cycle. It is not a checklist after deployment. It is a continuous security thread woven through planning, design, coding, testing, release, and maintenance. Without it, the gaps are inevitable.
At the planning stage, identity requirements define who can interact with the system, how authentication works, and what authorization rules apply. At design, architecture must account for role-based access, least privilege, and secure session handling. These elements become part of the core diagrams and API plans, not side notes.
During implementation, developers integrate protocols such as OAuth 2.0, OpenID Connect, and SAML directly in the codebase. Code review includes checks for secure credential storage, proper secret rotation, and input validation for identity-related endpoints. Testing addresses not only feature correctness but also authentication resilience, session hijacking resistance, and privilege escalation prevention.