Authentication and Access Control Questions

Comprehensive coverage of methods, protocols, design principles, and practical mechanisms for proving identity and enforcing permissions across systems. Authentication topics include credential based methods such as passwords and secure password storage, Multi Factor Authentication, one time passwords, certificate based and passwordless authentication, biometric options, federated identity and single sign on using Open Authorization, OpenID Connect and Security Assertion Markup Language, and service identity approaches such as Kerberos and mutual Transport Layer Security. Covers token based and session based patterns including JSON Web Token and session cookies, secure cookie practices, token lifecycle and refresh strategies, token revocation approaches, refresh token design, and secure storage and transport of credentials and tokens. Authorization and access control topics include role based access control, attribute based access control, discretionary and mandatory access control, access control lists and policy based access control, Open Authorization scopes and permission modeling, privilege management and the principle of least privilege, and defenses against privilege escalation and broken access control. The description also addresses cryptographic foundations that underlie identity systems including symmetric and asymmetric cryptography, public key infrastructure and certificate lifecycle management, secure key management and rotation, and encryption in transit and at rest. Common threats and mitigations are covered, such as credential stuffing, brute force attacks, replay attacks, session fixation, cross site request forgery, broken authentication logic, rate limiting, account lockout strategies, secrets management, secure transport, and careful authorization checks. Candidates should be able to design authentication and authorization flows for both user and service identities, evaluate protocol and implementation trade offs, specify secure lifecycle and storage strategies for credentials and tokens, and propose mitigations for common failures and attacks.