A fun and ridiculously easy maths unit which can be taken at either second or third year level. Lives up to its name, insofar as it covers both ciphers (from classical crytography to Diffie-Hellman and RSA) and codes (Hamming, Huffman, ...). Unfortunately it lacks any kind of depth, and omits swathes of material: e.g. linear feedback shift registers are covered but with no explanation of why you would want to use one. Modern symmetric-key cryptography is omitted entirely, with neither the ciphers used (DES, AES, Blowfish, ...) nor the ways in which they're used (CBC, CFB, ...). Wikipedia may be a good resource for those curious about this stuff. Alternatively, teach yourself cryptography the UCCan way and write your own implementation of your favourite cryptographic protocol for fun and profit.
In 2006, it was taught by CherylPraeger (mainly ciphers) and GregGamble (mainly codes). The former is by far the more entertaining of the two lecturers. The lecturers were held at 9am and not recorded. Lecture attendance is largely optional, fortunately, since all of the notes are available on the unit's Web site.
There are assignments every few weeks which are on the easy-but-tedious side, since you are expected to show evidence of having done by hand what any right-thinking UCCan would get a computer to do. Assignments also feature some easy proofs to do, to continue the pretence of this being a pure maths unit. There is an exam at the end of semester.