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 for third year undergraduate students as well as for graduate students. Prerequired courses are design of algorithms and probability.
Num.  Topic  Date  Handouts, exercises 
textbook 
1  Introduction.
Classic Encryption Systems 
24.2.03  Announcement  
2  Classic encryptions (continued); their cryptanalysis.  25.3.03 
Frequency Table Vigenre Applet 
1 
3  Perfect encryption systems.  3.3.03  EX1  2.1 
4

Basic
Number Theory 
4.3.03 
Proof from class 

5 
More Number
Theory 
10.3.03 
5.2 

6 
Chinese Remainder 
11.3.03 
5.2 

7 
Quadratic Residues

24.3.03 
EX2 

8  Number Theory: Summary  25.3.03  
9  RSA public key encryption.  31.3.03  4.3, 4.4  
10  RSA: Implementations and Attacks.
DiffieHellman Key Exchange 
1.4.03 
[Boneh]
4.5 8.2.2 

11  ElGamal Encryption.  7.4.03  5.1 (until p. 166)  
12  Data Encryption Standard (DES).  8.4.03  DES, Ex. 3 (ps) (word)  3.13.3 
13  Attacks on DES. Linear Cryptanalysis.  28.4.03  [Matsui]  
14  Modes of Operations.
Advanced Encryption Standard (AES). 
29.4.03  Ex 4 (ps) (word) 
3.4
Fips 197 
15  Digital Signatures:
RSA and Rabin's Signatures. 
12.5.03  6.1,
4.7 (modified) 

16  ElGamal Signature scheme.  13.5.03  6.2  
17  Digital Signature Algorithm (DSA).  19.5.03  6.3  
18  Cryptographic Hash functions.  20.5.03  7.17.3,7.5.  
19  Authentication,
CBCMAC. HMAC. 
26.5.03 
Ex 5
(ps)
(word) [BCK1] (ps) (pdf) 
3.4.1. 
20  Secure Socket Layer (SSL).  27.5.03  Slides: (1) (2) (3) (4) (5)  [Stallings, 14.1, 14.2] 
21  Threshold Secret Sharing.  2.6.03  11.1  
22  Secret Sharing.  9.6.03  11.2  
23  Summary Lecture.  10.6.03  
24  Example questions.  22.6.03 
Lectures hours:  Monday 1820, Room 244 Building 90 

Tuesday 1820. Room 140 Building 90 
Reception hours:  Monday 1517, Room 205 Building 58 (Math and CS) 
Email:  beimel at cs.bgu.ac.il 
Phone:  647 7858 