Download presentation

Presentation is loading. Please wait.

Published byHadley Jetton Modified over 3 years ago

1
Lecture 8: Coin Flipping by Telephone Wayne Patterson SYCS 654 Spring 2010

2
Coin Flipping by Telephone Originally presented by Manuel Blum, then at UC Berkeley (now at Carnegie-Mellon): M. Blum. Coin flipping by telephone. In Proceedings of IEEE Spring Computer Conference, pages 133--137. IEEE, 1982. Blum was Rene Peraltas thesis advisor Rene is a colleague who is now responsible for security in electronic voting at NIST

3
As Rene Posed the Problem Alice and Bob have decided to divorce. They are in different cities, want to decide who gets the (house, car, dog, …) They decide to flip a coin Naturally they dont trust each other …

4
Alice and Bob Agree on a Secure One-Way Function For example, the function could be a x (mod p), for an agreed- upon large prime number p and an agreed-upon primitive root a.

5
Alice Will Flip the Coin The act of flipping is the choice of a secret x, 1 < x < p-1. x is either odd or even (i.e. heads or tails) Alice chooses x (the flip) and announces to Bob the computation y = a x mod p.

6
What Does Bob Do? Bob receives y, and guesses that x is odd or even (heads or tails). Bob sends his guess to Alice. Alice verifies the result, whether Bob guessed right or wrong, and proves her decision by sending x to Bob. Bob can verify that Alice did not lie by performing the same computation y = a x mod p. If Alice lied about the value of x, Bob can prove the lie by the fact that the y he computes will not be the same y he had received.

Similar presentations

OK

Pass in HW6 now Can use up to 2 late days Can use up to 2 late days But one incentive not to burn them all: teams will get to pick their presentation day.

Pass in HW6 now Can use up to 2 late days Can use up to 2 late days But one incentive not to burn them all: teams will get to pick their presentation day.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on self awareness worksheets Ppt on earthquake free download Best ppt on earth day and night Ppt on self development plan Ppt on water softening techniques for managing Ppt on the periodic table of elements Ppt on indian railway reservation system Ppt on life of gautama buddha Ppt on conservation of environment in uae Ppt on trade fair in china