# Multi-Factor Authentication Multi-factor authentication requires evidence from more than one factor class, commonly knowledge, possession, or inherence. A password plus a code delivered to the same compromised device may provide less independence than the interface suggests. ## Notebook evidence [[Scanned_20260730-2016]] repeatedly binds accounts to telephone numbers, devices, recovery codes, PINs, and security questions. PDF pages 16, 22, 31, 35, 37, 41, and 42 show why factor independence matters: the same phone or email may be both authenticator and recovery route for multiple services. ## Continuity implication MFA increases resistance to single-factor compromise but also creates recovery obligations. The archive should record factor type, device or number, fallback route, enrollment date, current status, and revocation history without storing reusable secrets in navigation notes. ## Source - [[Scanned_20260730-2016]], PDF pages 16, 22, 31, 35, 37, and 41–42.