Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
4/8/2004
Homework 1
Due Thursday, 4/15/2004, at the beginning of class!
1
Substitution cipher [15 points]
Have a look at the substitution cipher in Lecture Notes 1 (section 3.2) and recall the definition of
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
6/12/2004
Homework 7
Due Friday noon, 6/18/2004
1
1.1
PRGs
PRG warmup
Recall the definition of a PRG. Consider the following attempt at constructing one: G(x) outputs x concatenated with the parity bit of x
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
5/13/2004
Homework 4
Due Tuesday, 5/20/2004
1
"Onebitstreching" PRG implies "polynomiallystreching" PRG
Assume that G is a PRG which stretches input by only one bit, i.e. for all inputs x, the length G(x
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
4/15/2004
Homework 2
Due Thursday, 4/22/2004 at the beginning of class.
1
Security Definitions [10+20 points]
Definition of some security property often goes like this: We call some communication scheme sec
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
5/25/2004
Solutions to homework 4
1
"Onebitstreching" PRG => "polynomiallystreching" PRG
Assume that G is a PRG which stretches input by only one bit, i.e. for all inputs x, the length G(x), of the outp
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
5/27/2004
Homework 5
Due Thursday, 6/03/2004
1
Constructing a PRG from a PRF
This question is designed so that you see a relation between a PRF and a PRG. You have seen in class that with some work one can b
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180, Spring'04
Lecture Summaries, Homeworks, Solutions, Handouts No textbook
[+ a tentative schedule for what's to come] [back to course main page], [shortcut to handout list]
[Lecture 1, week 1, 4/6/04] Introduction (lect1.pdf) Overview of goa
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
April 13, 2004
Lecture 3: OneWay Encryption, RSA Example
Lecturer: Stanislaw Jarecki
1
L ECTURE S UMMARY
We look at a different security property one might require of encryption, namely oneway security. Th
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
6/14/2004
Solutions to homework 5
1
Constructing a PRG from a PRF
This question is designed so that you see a relation between a PRF and a PRG. You have seen in class that with some work one can build a PRF
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
4/22/2004
Solutions to homework 2
1
Security Definitions [10+20 points]
Definition of some security property often goes like this: We call some communication scheme secure in the sense of resistance against
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
6/03/2004
Homework 6
Due Thursday, 6/10/2004
1
Symmetric encryptions from a PRP
Let P : {0, 1} {0, 1}m {0, 1}m be a PRP. Assume that m is polynomial in . Assume that every PPT adversary running in time t
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
4/23/2004
Homework 3
Due Tuesday, 5/04/2004 [ you get more than a week! ]
1
Authentication Scheme from OneWay Permutations
Let PPT algorithms (Gen, Sample, Eval) define a OWF (or OWP) {fi }iI . Suppose that
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
5/11/2004
Solutions to homework 3
1
Authentication Scheme from OneWay Permutations
Let PPT algorithms (Gen, Sample, Eval) define a OWF (or OWP) {fi }iI . Suppose that players U and B use the following authe
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
April 15, 2004
Lecture 4: OneWay Encryption vs. Indistinguishability
Lecturer: Stanislaw Jarecki
1
L ECTURE S UMMARY
Last time we saw an example of an encryption scheme, the "textbook RSA" scheme, which can
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180 May 4th, 2004 Guest Lecturer: Einar Mykletun
1
Symmetric Key Crypto
2
Two users who wish to communicate share a secret key Properties
High encryption speed Limited applications: encryption Based on permutations and substitutions No ma
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
April 6, 2004
Lecture 1: Crypto Overview, Perfect Secrecy, Onetime Pad
Lecturer: Stanislaw Jarecki (These notes incorporate material from Tal Malkin's Lecture 12 and Yevgeni Dodis's Lecture 1)
1
L ECTURE S
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
April 8, 2004
Lecture 2: Computational Notion of Security
Lecturer: Stanislaw Jarecki
1
L ECTURE S UMMARY
We introduce the notion of computational security, in contrast to the perfect security of last lectur
Introduction to Cryptography and Communication Security
ICS 180

Spring 2004
ICS 180: Introduction to Cryptography
6/3/2004
Handout 2: Symmetric Encryption from a PRF
A PRF is a very powerful source of (pseudo)randomness and therefore it can be immediately turned into powerful ciphers. The construction is very simple: just