Number Theory and Cryptography (MATH2068)


Cryptography is the branch of mathematics that provides the techniques for confidential exchange of information sent via possibly insecure channels. This unit introduces the tools from elementary number theory that are needed to understand the mathematics underlying the most commonly used modern public key cryptosystems. Topics include the Euclidean Algorithm, Fermat's Little Theorem, the Chinese Remainder Theorem, Möbius Inversion, the RSA Cryptosystem, the Elgamal Cryptosystem and the Diffie-Hellman Protocol. Issues of computational complexity are also discussed.

Our courses that offer this unit of study

Further unit of study information


Three 1 hour lectures, one 1 hour tutorial and one 1 hour computer laboratory per week.


2 hour exam, assignments, quizzes (100%)

Faculty/department permission required?


Unit of study rules

Prerequisites and assumed knowledge

6 credit points of Junior Mathematics units

MATH1014 or MATH1002 or MATH1902


MATH2988 or MATH3009 or MATH3024

Study this unit outside a degree

Non-award/non-degree study

If you wish to undertake one or more units of study (subjects) for your own interest but not towards a degree, you may enrol in single units as a non-award student.

Cross-institutional study

If you are from another Australian tertiary institution you may be permitted to underake cross-institutional study in one or more units of study at the University of Sydney.