Design ChallengesUser ComfortDesign PrinciplesLeast PrivilegeFail-Safe DefaultsEconomy of MechanismComplete MediationOpen DesignSeparation of PrivilegeLeast Common MechanismPsychological AcceptabilityConfidentiality, Integrity, Availability (CIA)ConfidentialityIntegrityAvailabilitySecurity ControlsAuthenticationAuthorizationNonrepudiationAuditingSecurity PatternsDirect Authentication PatternSealed Green Zone PatternLeast Common Mechanism PatternBrokered Authentication PatternPolicy-Based Access Control PatternThreat ModelingSummary