Department of Computer Science
COMP522 Individual coursework
Overall marking scheme
The coursework for COMP522 consists of two assignments, contributing to 25% of the final
mark. The contribution of the single assignments is as follows:
Assignment 1 12.5%
Assignment 2 12.5%
Failure in any assignment may be compensated for by higher marks in other components of
This document describes Assignment 2. Assignment 2 will be marked according to the
following broad criteria:
• correctness of the arguments;
• presence/absence of the evidence on the experiments;
• original contribution either in implementation, or analysis.
Aims of the Assignment 2
• to illustrate the practical aspects of using asymmetric cryptography, hash functions,
digital signatures for the message authentication;
• to illustrate the practical aspects of key exchange algorithms
• to test the students skills of using cryptographic primitives in programming with JCA;
• to test the students skills in the analysis of the experiments.
This assignment consists of two parts: on message authentication and on key exchange.
Comparison of methods for message authentication
This part of the assignment asks you to overview and compare the following methods for
message integrity, authenticaton and non-repudiation considered at lectures and Labs 4 and
• hash functions (for example SHA-256);
• RSA + SHA1 method considered at Lab 4;
• DSA method considered at Lab 4;
• HMAC-SHA256 considered at Lab 6.
For each method please give a short description, inlcuding the statement of what it can
be used for and under which assumptions, as well as what are possible advantages and
disadvantages of these methods. Illustrate your arguments by the results of experiments
(Lab 4, Lab 6, or of your own design).
Key Exchange for Four parties
This part of the assignment asks you to design and implement a variant of Diffie-Hellman
Key exchange protocol which would allow to exchange the secrets between four parties.
• describe a theoretical design, similar to that presented at the lecture for two-party DH
• using provided reference implementations of DH for two and three parties (Lab 5)
implement your design and demonstrate it works;
• write a report on the above, providing an evidence for your arguments.
You need to submit:
• Report (in *.pdf, *.doc,or *.docx format)
• Java code for your implementation
The work must be submitted electronically via Electornic Coursework Submission System.
This must be done by
17.00 on Friday, 6th of December, 2019
Please be aware that the standard University policies
• on plagiarism, collusion and fabricated data
www.liv.ac.uk/tqsd/pol_strat_cop/cop_assess/cop_assess.doc, Section 8
• on late submission
www.liv.ac.uk/tqsd/pol_strat_cop/cop_assess/cop_assess.doc, Section 6
are applied to this assignment.
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