MTH6115: Cryptography

Announcements

(10/01/2012) Course notes for Week 1 are available (below).

(13/01/2012) I have uploaded a few ciphers for you to decrypt (below).

(18/01/2012) There has been a clash in room booking for the Wednesday tutorial. This seem to have been resolved now. From now on, the Wednesday tutorial takes place in BR 3.02 (same time). Those of you who had questions to ask during the tutorial please feel free to email me and I will try to answer your questions by email or set an appointment to meet you.

(18/01/2012) My office hours have changed (see below).

(25/01/2012) Cipher Challenge rules are now available (see bottom of the page). The deadline for submission is 6th of February.

(07/02/2012) Wednesday tutorial is cancelled altogether. You can either attend the Thursday tutorial, or come to my office Thursdays 3-4pm.

(16/02/2012) Feedback questions can be collected from the envelopes hanging on my office door.

(21/03/2012) Past exams available (see below).

(23/03/2012) Only what I covered in lectures/assignments are examinable. So, for instance, if I stated a theorem in the lecture and didn't prove it, you are expected to know the statement of the theorem but not the proof.

(23/03/2012) Next week John Faben will be running "office hours" on my behalf, as I am going to be away. Time and location:

Tuesday 1pm (BR 3.02), and 3pm (FB 3.26)
Thursday 2pm (FB 3.28)

Information

Lecturer: Dr Behrang Noohi
Office Hours: Tues 2-3, Thurs 1-2
Course Information
Learning Outcomes (Key Objectives)

Lectures and Classes (Winter/Spring 2012)

Lectures: Tuesday 1pm (BR 3.02), Tuesday 3pm (FB 3.26), Thursday 9am (BR 3.02)
Exercise Classes: Wednesday 11am (BR 3.02), surnames A--H. Thursday 2pm (FB 3.28), surnames I--Z.
Assignments: These should be handed in to the ORANGE box on the GROUND floor.

Exercises

Exercises 1. Solutions
Exercises 2. Solutions
Exercises 3. Solutions
Exercises 4. Solutions
Exercises 5. Solutions
Exercises 6. Solutions
Exercises 7. Solutions
Exercises 8.

Ciphers for you to try

These are some more ciphers you can try to crack. I may make the solutions available at some point, but for now you are on your own.

Caesar shifts: CaesAll.txt — all in one file.
Affine substitution ciphers: AffAll.txt — all in one file.
Substitution ciphers (may or may not be affine): Sub1.txt, Sub2.txt, Sub3.txt, Sub4.txt, Sub5.txt.

A substitution cipher tool useful for frequency analysis.

Notes and Supplementary Data

PLease note that these notes may be different from what I cover in lectures. They are meant to provide the missing details that are skipped in lectures. There are also things in these notes that will not be covered in lectures.

Notes 1
Notes 2 — An example of breaking a substitution cipher using frequency analysis.
Notes 3
Notes 4
Notes 5
Notes 6
Notes 7
Notes 8
Notes 9
Notes 10
Notes 11

Cipher Challenge

The rules are now that of this year’s version. Please read VERY CAREFULLY, and make sure you understand everything contained therein.

NB: It seems that on Microsoft Windows the Notepad application produces the nearest approximation to plain text. Please remember to press ENTER (also called RETURN) at the ends of your files.

Rules for Part 1 (PDF).
Rules, and ciphers to be broken, for Part 2

Past Papers

Solutions to past papers will NOT be made available.

2011
2010
2009
2008
2007
2006
2005
2004

Last updated: 23 March 2012