Webster dictionary defines cryptography as: ``The enciphering and deciphering of messages in secret code or cipher.'' However, modern cryptography is a much broader field; it provides algorithms and protocols which protect honest parties from malicious parties. Malicious parties can, for example, eavesdrop to the communication on the Internet and try to read messages sent by other parties; they can try to impersonate other parties, or login to computers without permission. Basic topics in cryptography include secure encryption, digital signatures, and authentication.
In this course I will discuss these topics, their realizations, and applications. The material covers cryptosystems that are both practical and theoretically interesting. To achieve this goal, I'll also teach some background in number theory that is necessary to understand modern cryptosystems such as RSA. This is a 4credit course, consisting of two weekly 2hour meetings. It is intended third year undergraduate students as well as for graduate students. Prerequired course is the algorithms course.
Num.  Topic  Date  Handouts, exercises 
textbook 
1  Introduction.
Classic Encryption Systems 
11.3.02  Announcement  
2  Classic encryptions (continued); their cryptanalysis.  12.3.02  Frequency Table  1 
3  Perfect encryption systems.  18.3.02  2.1  
4  Data Encryption Standard (DES).  19.3.02  DES, Ex. 1 (ps) (word) cryptogram  3.13.3 
5  Attacks on DES. Linear Cryptanalysis.  8.4.02  [Matsui]  
6  Modes of Operations.
Advanced Encryption Standard (AES). 
9.4.02  Ex 2 (ps) (word) 
3.4
Fips 197 
7 (3 hrs)  Introduction to Number Theory: modular arithmetic, Euclid's algorithm.  22.4.02  1.1.1, 4.2, 4.4  
8 (3 hrs)  Number Theory: Chinese remainder theorem, structure of Zp, Quadratic Residues in Zp  23.4.02  4.2  
9 (3 hrs)  Structure of Zp*q.
The RSA public key encryption. 
29.4.02  Ex 3 (ps) (word)  4.3, 4.4 
10 (3 hrs)  RSA: Implementations and Attacks.
Intro to DiffieHellman Key Exchange, ElGamal Encryption. 
30.4.02 
[Boneh]
5.1 (until p. 166), 8.2.2 

11 (3 hrs)  DiffieHellman Key Exchange, ElGamal Encryption.  6.5.02  5.1 (until p. 166), 5.1.2 8.2.2  
12 (3 hrs)  Digital Signatures: Definitions, Rabin's Signature scheme.  7.5.02  6.1, 4.7 (modified)  
13 (3 hrs)  ElGamal Signature scheme.
Cryptographic Hash functions. 
13.5.02  Ex 4 (ps) (word)  6.2
7.17.2 
14 (3 hrs)  Cryptographic Hash functions. Message Authentication Codes (MAC), CBCMAC. 
14.5.02  7.17.3,7.5 3.4.1. 

15 (3 hrs)  HMAC.
Threshold Secret Sharing. 
20.5.02  [BCK1] (ps) (pdf) 
[BCK1]
[BCK2] 11.1 
16 (3 hrs)  Secure Socket Layer (SSL).  21.5.02  Slides: (1) (2) (3) (4) (5)  [Stallings, 14.1, 14.2] 
17  Example questions  9.7.02 
Lectures hours:  Monday 1820, Room 136 Building 90 
Tuesday 1820, Room 109 Building 34  
Reception hours:  Tuesday 1618, Room 205 Building 58 (Math and CS) 
Email:  beimel at cs.bgu.ac.il 
Phone:  647 7858 