We study the problem of searching on data that is encrypted using a public key system. Consider user Bob who sends email to user Alice encrypted under Alice’s public key. An email gateway wants to test whether the email contains the keyword “urgent” so that it could route the email accordingly. Alice, on the other hand does not wish to give the gateway the ability to decrypt all her messages. W...

A sequence S is nonrepetitive if no two adjacent blocks of S are the same. In 1906 Thue proved that there exist arbitrarily long nonrepetitive sequences over 3 symbols. We consider the online variant of this result in which a nonrepetitive sequence is constructed during a play between two players: Bob is choosing a position in a sequence and Alice is inserting a symbol on that position taken fr...

Alice is the LHC experiment dedicated to heavy ion (Pb, Ca) physics. Alice will be installed in point 2 of LHC, the former point 2 of LEP. The luminosity at the interaction point will be in the order of 10 (10 for p–p). Consequently, the radiation level in Alice will be comparatively low. We will use the existing infrastructure. Therefore, no noticeable civil engineering work will be necessary....

We first consider teleportation of entangled states shared between Claire and Alice to Bob1 and Bob2 when Alice and the two Bobs share a single copy of a GHZ state and where all the four parties are at distant locations. We extend this result to a more general state than GHZ-state and show that still a class of pure entangled states can be teleported, where the entanglement of this class ranges...

We investigate the physical-layer security of indoor hybrid parallel power-line/wireless orthogonal-frequency division-multiplexing (OFDM) communication systems. We propose an artificial-noise (AN) aided scheme to enhance the system’s security in the presence of an eavesdropper by exploiting the decoupled nature of the power-line and wireless communication media. The proposed scheme does not re...

Consider a wireless communication system in which Alice wishes to transmit a message to Bob in the presence of an eavesdropper, Eve. We consider the design of a communication technique that allows Alice to send a message such that Bob can decode it but Eve can get little information about the message. This scenario is a classic example of the wiretap channel, for which several researchers have ...

Quantum private query (QPQ) is a kind of quantum protocols to protect both users’ privacy in their communication. There is an interesting example, that is, Alice wants to buy one item from Bob’s database, which is composed of a quantity of valuable messages. QPQ protocol is the communication procedure ensuring that Alice can get only one item from Bob, and at the same time, Bob cannot know whic...