Quantum secure conditional direct communication via EPR pairs

This paper presents the first quantum entanglement establishment scheme for strangers who neither pre-share any secret nor have any authenticated classical channel between them. The proposed protocol requires only the help of two almost dishonest third parties (TPs) to achieve the goal. The security analyses show that the proposed protocol is secure against not only an external eavesdropper's attack, but also the TP's attack.

We suggest a method for teleporting an unknown quantum state. In this method the sender Alice first uses a Controlled-Not operation on the particle in the unknown quantum state and an ancillary particle which she wants to send to the receiver Bob. Then she sends ancillary particle to Bob. When Alice is informed by Bob that the ancillary particle is received, she performs a local measurement on the particle and sends Bob the outcome of the local measurement via a classical c...

In this paper, a bidirectional quantum teleportation protocol based on Einstein-Podolsky-Rosen (EPR) pairs and entanglement swapping is proposed. In this scheme, two users can simultaneously transmit an unknown single-qubit state to each other. The implementation of the proposed scheme is easier in experiment as compared to previous work. By utilizing this bidirectional quantum teleportation protocol, a bidirectional quantum secure direct communication scheme without carrying...

We present a quantum secure direct communication(QSDC) scheme as an extension for a proposed supervised secure entanglement sharing protocol. Starting with a quick review on the supervised entanglement sharing protocol -- the "Wuhan" protocol [Y. Li and Y. Liu, arXiv:0709.1449v2], we primarily focus on its further extend using for a QSDC task, in which the communication attendant Alice encodes the secret message directly onto a sequence of 2-level particles which then can be ...

We propose a scheme by which two parties can secretely and simultaneously exchange messages. The scheme requires the two parties to share entanglement and both to perform Bell-state measurements. Only two out of the four Bell states are required to be distinguished in the Bell-state measurements, and thus the scheme is experimentally feasible using only linear optical means. Generalizations of the scheme to high-dimensional systems and to multipartite entanglement are conside...

A protocol for quantum bit commitment is proposed. The protocol is feasible with present technology and is secure against cheaters with unlimited computing power as long as the sender does not have the technology to store an EPR particle for an arbitrarily long period of time. The protocol is very efficient, requiring only tens of particles.

Unconditional security in quantum key distribution (QKD) relies on authenticating the identities of users involved in key distribution. While classical identity authentication schemes were initially utilized in QKD implementations, concerns regarding their vulnerability have prompted the exploration of quantum identity authentication (QIA) protocols. In this study, we introduce a new protocol for QIA, derived from the concept of controlled secure direct quantum communication....

We propose a simultaneous quantum secure direct communication scheme between one party and other three parties via four-particle GHZ states and swapping quantum entanglement. In the scheme, three spatially separated senders, Alice, Bob and Charlie, transmit their secret messages to a remote receiver Diana by performing a series local operations on their respective particles according to the quadripartite stipulation. From Alice, Bob, Charlie and Diana's Bell measurement resul...

Two QKD protocols with limited classical Bob who performs only limited classical operations (preparing a (fresh) qubit in the classical basis and send it or doing nothing) are presented and are proved completely robust. As limited classical Bob can deterministically choose the bits, we use the feature to construct a quantum secure direct communication protocol, which is the direct communication of secret messages without first producing a shared secret key.

We presen a secure direct communication protocol by using step-split Einstein-Podolsky-Rosen (EPR) pair. In this communication protocol, Alice first sends one qubit of an EPR pair to Bob. Bob sends a receipt signal to Alice through public channel when he receives Alice's first qubit. Alice performs her encoding operations on the second qubit and sends this qubit to Bob. Bob performs a Bell-basis measurement to draw Alice's information. The security of this protocol is based o...