ICS 180, Spring'04
Lecture Summaries, Homeworks, Solutions, Handouts
[+ a tentative schedule for what's to come]
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[Lecture 1, week 1, 4/6/04] Introduction
Overview of goals of cryptography. Shannon's definition of secrecy. Classic ciphers and their
. One-time pad encryption: Its
and, unfortunately, it’s
the need for computational notions of hardness.
[Lecture 2, week 1, 4/8/04] Computational Notion of Hardness (+ short review of
Probabilistic algorithms, asymptotic analysis of algorithm running time, polynomial time vs.
exponential time, notions of negligible adversarial advantage and of computational hardness.
Example: Indistinguishability of Private-Key Encryption.
Homework 1 (due Thursday, 4/15/04):
Solutions to Homework 1:
[Lecture 3, week 2, 4/13/04] Computational Notion of Hardness (cont): One-way
encryption and RSA example
We define the notion of one-way secure encryption. We use RSA encryption as an example to
illustrate how efficiency/hardness of known attacks on RSA is captured by computational
notion of security involving the notion of efficient algorithms and negligible probability.
[Lecture 4, week 2, 4/15/04] One-way encryption vs. Indistinguishable encryption.
We compare the two computational notions of security for encryption. We show that no
deterministic cipher, including the textbook RSA can be indistinguishable. We show other ways
in which encryption which is assumed one-way secure can still have security flaws, e.g. it can
leak some specific plaintexts, some specific bits of every plaintext, etc. This shows the gap
between one-way security and indistinguishability for encryption, and motivates finding
encryption schemes which satisfy the latter, stronger notion.