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Computer Science Tripos Syllabus - Security
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Lecturers: Professor R.J. Anderson, Dr M.G. Kuhn, Mr G. Danezis

No. of lectures: 16

Prerequisite courses: Introduction to Security, Discrete Mathematics, Economics and Law, Operating Systems, Digital Communication I and II, Information Theory and Coding

This course is a prerequisite for E-Commerce.


This course aims to give students a thorough understanding of computer security technology. This includes high-level issues such as security policy (modelling what ought to be protected) and engineering (how we can obtain assurance that the protection provided is adequate). It also involves the protection mechanisms supported by modern processors and operating systems; cryptography and its underlying mathematics; electrical engineering issues such as emission security and tamper resistance; and a wide variety of attacks ranging from network exploits through malicious code to protocol failure.


  • What is security? Introduction and definitions: different meanings of principal, system, policy, trust. Diversity of applications. Relationship with distributed system issues such as fault-tolerance and naming.

  • Multilevel security The Bell-LaPadula policy model; similar formulations such as the lattice mode, noninterference and nondeducibility. Composability. Real MLS systems, and real problems: covert channels, the cascade problem, polyinstantiation, dynamic and non-monotonic labelling. Flexibility, usability and compatibility.

  • Multilateral security policy models Compartmented systems, Chinese Wall, the BMA policy. Inference security: query controls, trackers, cell suppression, randomisation, stateful controls, and active attacks.

  • Banking and bookkeeping systems Double-entry bookkeeping, the Clark-Wilson policy model. Separation of duties, and its implementation problems. Payment systems and how they fail: SWIFT, ATMs.

  • Monitoring systems Alarms. Sensor defeats; feature interactions; attacks on communications; attacks on trust. Examples: antivirus software, tachographs, prepayment electricity meters. Seals; electronic postal indicia.

  • Telecommunications security Attacks on metering, signalling, switching and configuration. Attacks on end systems. Feature interactions. Mobile phone issues: protection issues in GSM, GPRS, 3g. Surveillance technology and practice. Models of attacks on communications systems. Worms and viruses.

  • Anonymity and peer-to-peer systems Dining cryptographers; mix-nets. Models of opponents. Surveillance versus service denial. Peer-to-peer systems; resilience and censorship resistance.

  • Hardware engineering issues. Tamper resistance: smartcards, cryptoprocessors. Mechanical and optical probing, fault induction, power analysis, emission security.

  • Signal processing issues. Biometrics: fingerprint readers, iris scanners, signature recognition. Information hiding: watermarks, digital fingerprints, steganography; jam-resistance and low-probability of-intercept communications.

  • Stream ciphers. Historical systems: Caesar, Vigenère, Playfair. Revision of information theory: unicity distance, the one-time-pad, attacks in depth. Shift register based systems: the multiplexer generator, the filter generator, A5. Attacks on these systems: divide and conquer, fast correlation.

  • Block ciphers. Design of block ciphers: SP-networks and Feistel ciphers. Differential and linear cryptanalysis. AES; Serpent; DES. Revision of the random oracle model: modes of operation. Splicing and collision attacks. Message authentication codes and hash functions.

  • Symmetric cryptographic protocols. Needham-Schroder, Otway-Rees, Kerberos, the wide-mouthed frog. The BAN logic. Applying BAN to verify a payment protocol.

  • Asymmetric cryptosystems. Revision of public-key mathematics: RSA, ElGamal, Diffie-Hellman. Elliptic curve systems, factoring algorithms. Advanced primitives: identity based schemes; threshold schemes; zero knowledge; blind signatures.

  • Asymmetric cryptographic protocols. Needham-Schroder, Denning-Sacco, TMN. Applications including SSL, SSH, SET, PGP and PEM. The BAN logic applied to public key systems.

  • Rights management, interoperability control and economics. Copyright management systems; accessory control systems; the TC architecture. Security economics. Tensions between security and competition.

  • Security engineering. Why is security management hard? Risk reduction versus transference; due diligence and the role of insurance. Threat trees; risk models; robustness; dependability; engineering disciplines. Verification and evaluation: TCSEC, ITSEC and the Common Criteria. Interaction with the regulatory environment, from data protection through RIP to export control.


At the end of the course students should be able to tackle an information protection problem by drawing up a threat model, formulating a security policy, and designing specific protection mechanisms to implement the policy.

Recommended books

* Anderson, R. (2001). Security engineering. Wiley.
Stinson, D.R. (2002). Cryptography: theory and practice. Chapman & Hall (2nd ed.). Schneier, B. (1995). Applied cryptography: protocols, algorithms, and source in C. Wiley (2nd ed.).

Further reading:

Kahn, D. (1966). The codebreakers: the story of secret writing. Weidenfeld and Nicolson.
Cheswick, W.R., Bellovin, S.M. & Rubin, A.D. (2003). Firewalls and Internet security: repelling the wily hacker. Addison-Wesley (2nd ed.).
Howard, M. & leBlanc, D. (2002). Writing secure code. Microsoft Press (2nd ed.).
Gollmann, D. (1999). Computer security. Wiley.
Koblitz, N. (1994). A course in number theory and cryptography. Springer-Verlag (2nd ed.).
Neumann, P. (1994). Computer related risks. Addison-Wesley.
Biham, E. & Shamir, A. (1993). Differential cryptanalysis of the data encryption standard. Springer-Verlag.
Leveson, N.G. (1995). Safeware: system safety and computers. Addison-Wesley.
Davies, D.W. & Price, W.L. (1984). Security for computer networks. Wiley.
Beker, H. & Piper, F. (1982). Cipher systems. Northwood.
Cohen, F.B. (1994). A short course on computer viruses. Wiley (2nd ed.).

next up previous contents
Next: Specification and Verification I Up: Michaelmas Term 2004: Part Previous: Information Theory and Coding   Contents
Christine Northeast
Wed Sep 8 11:57:14 BST 2004