et Passwords -weak authentication Usually fixed Stored either in the clear, or encrypted with a owe Rules reduce the chance of easy passwords Salt increases search space for a dictionary attack There are many examples using password-based authentication how to manage passwords 復大辱软件学院
11 Passwords -weak authentication • Usually fixed • Stored either in the clear, or “encrypted” with a OWF • Rules reduce the chance of easy passwords • Salt increases search space for a dictionary attack • There are many examples using password-based authentication – how to manage passwords
let Example: UNIX passwords letc/passwd letc/shadow Username: password: UID: GID: USERINFO: HOME: SHELL User Password file mpassa exrygbzy千 kgnosfix hash function ggjoklbsz 12 復大辱软件学院
12 User Password file exrygbzyf kgnosfix ggjoklbsz … … mypasswd hash function Example: UNIX passwords /etc/passwd /etc/shadow Username: password: UID : GID: USERINFO: HOME: SHELL