Communication and Third Parties: Costs, Cues, and Confidentiality by Krishnan Eswaran Doctor of Philosophy in Engineering—Electrical Engineering and Computer Sciences and the Designated Emphasis in Communication, Computation, and Statistics University of California, Berkeley Professor Michael Gastpar, Chair This thesis tells the story of Alice and Bob, who wish to share information. However, Al...

Introduced in 2009 in [6] bitcoin is one of the first decentralized currency. It’s called crypto-currency, since it uses cryptography to secure transactions and assets. Bitcoin operation is based on so-called public ledgers that can be shortly described as follows. Assume there are two parties Alice and Bob (as usual), such that Alice wants to buy something from Bob. Assume they both have walle...

In this paper we consider a new and efficient optimistic nonrepudiation protocol. In a non-repudiation protocol, during which Alice wants to transmit a message to Bob, Alice has to send a non-repudiation of origin evidence to Bob (attesting that Alice is at the origin of the transmitted message), and Bob has to send a non-repudiation of receipt evidence to Alice (attesting Bob’s receipt of the ...

The game. Alice and Bob decide to play the following infinite game on the real number line. A subset S of the unit interval [0, 1] is fixed, and then Alice and Bob alternate playing real numbers. Alice moves first, choosing any real number a1 strictly between 0 and 1. Bob then chooses any real number b1 strictly between a1 and 1. On each subsequent turn, the players must choose a point strictly...

In this work, we consider a scenario where two multiple-aperture legitimate nodes (Alice and Bob) communicate by means of Free-Space Optical (FSO) communication in the presence of a multipleaperture eavesdropper (Eve), which is subject to pointing errors. Two different schemes are considered depending on the availability of channel state information (CSI) at Alice: i) the adaptive scheme, where...

Suppose Alice wants to perform some computation that could be done quickly on a quantum computer, but she cannot do universal quantum computation. Bob can do universal quantum computation and claims he is willing to help, but Alice wants to be sure that Bob cannot learn her input, the result of her calculation, or perhaps even the function she is trying to compute. We describe a simple, efficie...

The zero-error capacity of a discrete classical channel was first defined by Shannon as the least upper bound of rates for which one transmits information with zero probability of error [C. Shannon, IRE Trans. Inform. Theory, IT-2(3):8–19, 1956]. Here, we define the quantum zero-error capacity, a new kind of classical capacity of a noisy quantum channel C represented by a trace-preserving map (...