HW5, Q2

HW5, Q2

shelly (guest) 20 Jan 2020 14:57

hi, i have some questions regarding question 2:

2. For the function we defined in question 2 for auction, what happens in a situation where an adversary controls the seller? If the seller is corrupted then the adversary can decide who wins because it can choose for the seller the final output to be (B, some random number). Nobody really checks that this random number is the real bid of B, thus the adversary can make B win even in the ideal world.

3. The logic of section A: I did not understand how it is possible that A* outputs b. By the definition of the function, the output of A should be nothing, so if A* outputs b, it contradicts the definition of the function.

Thanks!!

Last edited on 20 Jan 2020 19:07 by nbitansky Show more

Re: HW5, Q2

nbitansky 20 Jan 2020 19:12

1. The two properties (input privacy and input independence) are related but somewhat different as we discussed in class. The proofs are indeed quite similar. Also please don't write answers for questions from the hw in the forum.
2. Right.
3. $A^*$ can output whatever it wants, it's not following the protocol for computing the function.