Question: Suppose Alice knows that Bob's pseudorandom key generator has a slight bias and that with probability 5 1 % it produces a key with more

Suppose Alice knows that Bob's pseudorandom key generator has a slight bias and that with probability 51% it produces a key with more 1's than 0's. Alice and Bob play the CI Game. Alice chooses messages m0=0000 and m1=1111 to Bob, who randomly chooses b in {0,1} and encrypts mb with a one-time pad using his pseudorandom key generator. He gives the ciphertext c=mbr (where r is his pseudorandom key) to Alice. Alice computes s=cm0. If s has more 1's than 0's, she guesses that b=0. If not, she guesses that b=1. For simplicity in the following, we assume that the message lengths are odd (so there cannot be the same number of 1's and 0's).(a) Show that exactly one of m0r and m1r has more 1's than 0's.(b) Show that P(s has more 1's b=0)=.51(c) Show that P(s has fewer 1's b=1)=.51(d) Show that Alice has a probability .51 of winning.

Step by Step Solution

There are 3 Steps involved in it

1 Expert Approved Answer
Step: 1 Unlock blur-text-image
Question Has Been Solved by an Expert!

Get step-by-step solutions from verified subject matter experts

Step: 2 Unlock
Step: 3 Unlock

Students Have Also Explored These Related Programming Questions!