# TMA4160 Cryptography - Fall 2017

 Lecturer: Assistant: Schedule Kristian Gjøsteen Herman Galteland Monday 10-12 A34 (Trondheim Handelshøyskole, right next to U33) Friday 12-14 B1 Wednesday 16-17 Usually in U33, sometimes in Nullrommet (380A) Monday 12.30-13.30 848 in SBII December 14

## What you should know before taking the course

You should be familiar with basic abstract algebra such as groups, rings and fields.

It is helpful, but not required, to know something about computational complexity and the analysis of algorithms. Using a computer algebra system (or equivalent) is required for some of the exercises. Previous experience with computer algebra systems is helpful, but not required.

## Reference group

 Name E-mail @stud.ntnu.no Jenny Kvamme Høvik jennykh stud.ntnu.no Juliette Lemains juliettl stud.ntnu.no Morten Ravnemyr mortrav stud.ntnu.no

## Course material

Lecture notes:

• These notes follow the lectures fairly closely, but will be updated throughout the course.

Main book:

Supplements:

You should be able to get by with just the lecture notes (and possibly the supplements), but many of you will find Stinson useful. Note that Stinson does not cover the entire curriculum.

The curriculum is defined to be the material covered by the lecture notes, the lectures and the exercises.

## Messages

8/1: The grading is done. Statistics: A - 5, B - 4, C - 4, D - 10, E - 8, F - 9.

• 1a: Most of you happily divide by 3 modulo 270. Except for those that compute exponents modulo 271…
• 1b: While this problem did involve a lot of computation, very few could use Pohlig-Hellman properly.
• 3a: Many wanted the hash function to hide all information about the message, but it doesn't.

17/12: This year's exam and solution sketch.

28/11: Lattice-based cryptography as covered in the lectures and lecture notes is part of the curriculum. (Two specific cryptosystems, LWE and NTRU, mentioned only in the lectures are not on the curriculum.)

24/11: Regarding Problem 4 on the 2008 exam: Stinson uses the equation $( \delta = k + a \gamma$), while I used $( \delta = k - a \gamma$) in today's lecture, which explains the wrong result…