CEC 461 Information systems Security CA 2026

About this paper

CEC 461: A mid-semester examination in Information Systems Security (CEC461) from the University of Buea's College of Technology, 2025/2026 academic year, covering five questions worth a total of 21 marks over 2 hours. The paper tests core security concepts: publish/subscribe IoT event-driven systems and read/write/delete access-control reasoning across system log, wiki and blog files; the one-way (hash) function design underlying password-checking authentication schemes, including building the scheme from a userid/password table; hash-chain construction from an initialization vector and user authentication via hash comparison, plus a quantitative exponential-back-off PIN-lockout attack-probability calculation against a 4-digit PIN over a 3-hour window; deriving access-control lists (ACLs) and an equivalent role-based access control (RBAC) scheme from a given access-control matrix across four files and four users; and classifying operations as permitted or prohibited under the Biba integrity model's no-write-up (*-property) rule given a table of subject integrity levels and objects. The source scan had a duplicated sentence in Question 1 (reproduced as printed and flagged) and appeared to be missing the (a)/(b) parts of Question 1 (only (c) and (d) were legible), which were not fabricated.