ps7 - Computer Science and Engineering, UCSD CSE 207:...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Computer Science and Engineering, UCSD Spring 11 CSE 207: Modern Cryptography Instructor: Mihir Bellare Problem Set 7 May 18, 2011 Problem Set 7 Due: Wednesday May 25, 2011, in class. Problem 1. [45 points] Generation of random numbers on systems is difficult and error-prone. This problem explores ways of making ElGamal signature generation deterministic. Let p,q 3 be primes such that p = 2 q + 1. Let g be a generator of the cyclic group Z * p . Let H : { 0 , 1 } * Z p - 1 be a random oracle. 1. [20 points] We consider re-using randomness accross different signatures, which corresponds to the signature scheme DS = ( K , S , V ) whose algorithms are: algorithm K x $ Z p - 1 X g x mod p k $ Z * p - 1 return ( X, ( x,k )) algorithm S H (( x,k ) ,M ) m H ( M ) r g k mod p s ( m - rx ) k - 1 mod ( p - 1) return ( r,s ) algorithm V H ( X,M, ( r,s )) m H ( M ) if ( r 6∈ Z * p OR s / Z p - 1 ) then return 0 if ( X r · r s g m (mod p )) then return 1 else return 0
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/31/2011 for the course CSE 207 taught by Professor Daniele during the Winter '08 term at UCSD.

Page1 / 2

ps7 - Computer Science and Engineering, UCSD CSE 207:...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online