Download presentation

Presentation is loading. Please wait.

Published byPeter Thornton Modified over 2 years ago

1
Princeton University COS 433 Cryptography Fall 2007 Boaz Barak COS 433: Cryptography Princeton University Fall 2007 Boaz Barak Lectures 1-6: Short Recap

2
2 Perfectly Secure Encryption E x0x0 y x1x1 I can’t guess if it was x 0 or x 1 with prob better than ½ One time pad achieves this for unbounded adversary with |key| ¸ |message| Pseudorandom Generators G I can’t tell if I’m seeing G(s) or just lots of random coins! s y $$$$$$$$$$$$$$ We conjecture that they exist. (PRG Axiom) If we’re right, can get encryption with |key| < |message length|

3
3 Pseudorandom Functions (PRF) fkfk x y I don’t know what’s inside this box! Theorem: PRG Axiom ) 9 PRF

4
4 Ideal scheme using random function E Security of PRF-based Constructions E fkfk Encryption scheme using PRF. Can adversary succeed? 1) Prove that ideal scheme is secure. 2) Show this implies security for real scheme: Otherwise all system is one big adversary for the PRF.

5
5 CPA Secure Encryption E x0x0 y x1x1 E They gave me encryption box to play with and I still can’t guess if it’s x 0 or x 1 w/ prob > ½ + ² Theorem: 9 PRF ) 9 CPA-secure encryption Construction: E k (x) = choose r 2 R {0,1} n send (r, f k (r) © x)

Similar presentations

Presentation is loading. Please wait....

OK

Ryan Henry I 538 /B 609 : Introduction to Cryptography.

Ryan Henry I 538 /B 609 : Introduction to Cryptography.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on laws of liquid pressure Performance based pay ppt online Ppt on principles of object-oriented programming concepts Ppt on reign of terror Free download ppt on diversity in living organisms Time of flight ms ppt online Ppt on quality educational programs Ppt on corporate social responsibility as per companies act 2013 Ppt on total parenteral nutrition contraindications Ppt on 21st century skills assessment