Fall 2007
CS6260 - Applied Cryptography

Time: Tu, Th: 12:05-1:25pm.
Place: TBA.
Instructor: Alexandra (Sasha) Boldyreva.
Email: aboldyre@cc (dot) gatech (dot) edu. Please include "CS6260" in the subject.
Office hours: TBA.
TA: TBA.

Announcements: Unfortunately, during the first week of classes I have to be at Crypto 2007 conference. An experienced Ph.D. student specializing in crypto will give the first overview lecture on Tuesday August 21st. There will be no class on Thursday August 23rd. I will be answering emails during this time. I apologize for the inconvenience.

Textbooks, notes and lecture slides. There is no required textbook. Lecture notes, slides and additional references are available online. Click the link in the beginning of the papragraph for all the materials.

Content. This is a 3-credit graduate-level introduction to modern cryptography course. We consider the classical goals of cryptography such as data privacy, authenticity and integrity. Topics include pseudorandom functions and permutations, block ciphers, symmetric encryption schemes, security of symmetric encryption schemes, hash functions, message authentication codes (MACs), security of MACs, PKI, public-key (asymmetric) encryption, digital signatures, security of asymmetric encryption and digital signature schemes, secret sharing, threshold cryptography.

You will learn how various cryptographic schemes work and will discuss how they are used in practice. But the main objective is more fundamental. The goal is to build the understanding of what "secure" is and how to evaluate and measure security. We try to understand what does it mean for a cryptographic scheme to be "secure" by studying definitions of security of various primitives. You will learn how to analyze security of a cryptographic scheme and determine whether or not it is secure.

Cryptography is only one part of a much broader area of computer security. There are many topics that are beyond the scope of cryptography and will not be covered in this course, such as viruses, worms, buffer overflow and denial of service attacks, access control, intrusion detection and etc. We do not consider implementation issues in depth. Students interested in these topics are advised to take Network Security (CS6262) and Advanced Systems and Network Security (CS8803) courses. Foundations of Cryptography (CS8803) course studies complementary, more theoretical and often more advanced topics of cryptography.

Prerequisites. No previous knowledge of cryptography is necessary. This course is about applying theory to practical problems, but it is still a theory course. The main requirement is basic "mathematical maturity". You have to be able to read and write mathematical definitions, statements and proofs. I expect that you did well in your undergraduate discrete math class and took basic algorithms and computibility/complexity theory classes. In particular, you have to know how to measure the running time of an algorithm and it is helpful to understand the notion of reducing one problem to another. You also have to know very basic probability theory. All necessary elements of number theory will be presented in class. No programming will be required. If you have doubts whether you have the right background please email or come to see me.

Requirements. There will be weekly (and sometimes bi-weekly) homeworks (50%), a midterm (20%) and a final (30%).

Rules. Georgia Tech and College of Computing academic Honor Code applies. Homeworks are announced in class and are posted on the class web page. You can work on the homeworks individually or in pairs, but you have to write and turn in your own solutions and indicate the name of your collaborator, if any. You cannot search the Internet to find the solutions. You cannot ask your friends for the solutions from the previous years. Homework solutions should be turned in in class, stapled, before the lecture starts, on a due day (usually Thursday). If you are unable to attend a lecture when a homework is due, you can email me (and cc the TA) a postscript or a PDF file with your solutions before the time of the class. No late homeworks will be accepted. Please report any typos you find in the notes, slides, homeworks or the solutions. During exams you can use the on-line lecture notes and slides posted on the class web page and your own notes.