The quantum cryptographic switch

Abstract

We illustrate using a quantum system the principle of a cryptographic switch, in which a third party (Charlie) can control to a continuously varying degree the amount of information the receiver (Bob) receives, after the sender (Alice) has sent her information. Suppose Charlie transmits a Bell state to Alice and Bob. Alice uses dense coding to transmit two bits to Bob. Only if the 2-bit information corresponding to choice of Bell state is made available by Charlie to Bob can the latter recover Alice's information. By varying the information he gives, Charlie can continuously vary the information recovered by Bob. The performance of the protocol subjected to the squeezed generalized amplitude damping channel is considered. We also present a number of practical situations where a cryptographic switch would be of use.Comment: 7 pages, 4 Figure

Semi-quantum communication: protocols for key agreement, controlled secure direct communication and dialogue

“…This controlled communication scheme is based on quantum cryptographic switch scheme proposed in the past [74] and has been shown to be useful in almost all the controlled communication schemes [65,[75][76][77].…”

Quantum cryptography over non-Markovian channels

“…Hierarchi-cal quantum communication schemes are aimed to deal with these problems, when either only single sender holds all the information [16] or it is distributed among two of them [17]. We may consider another important scenario, where a controller supervises the communication among all the remaining users, and he can maintain his control by making sure that the communication is not accomplished without his consent [11,18,19]. Further, a scheme for quantum controlled communication based on a quantum cryptographic switch has been proposed recently, which allows the supervisor to control even the amount of information he wishes to share with the other users in a continuously varying degree [18,19].…”

“…The feasibility of implementation of various quantum communication schemes when subjected to noisy environment has been analyzed in the past. In particular, the schemes of QKD [20], QKA [20], controlled DSQC (CDSQC) [19], QSDC [20], CQD [18], QD [20], asymmetric QD (AQD) [21], con-trolled bidirectional remote state preparation [22], among others, have been considered under the influence of both purely dephasing and damping noises. Most of these investigations (cf.…”

“…Most of these investigations (cf. [18][19][20][21]) were restricted to the domain of Markovian environments [23,24], though, some attempts have been made to study the effects of non-Markovian environments on quantum communication schemes, such as teleportation [25,26], densecoding [26] and entanglement swapping [27,28]. The security of a QKD protocol has also been analyzed over non-Markovian depolarizing channel [29].…”

Quantum e-commerce: a comparative study of possible protocols for online shopping and other tasks related to e-commerce

“…Since then several quantum protocols have been proposed for various practical tasks that require security ( [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and references therein). For example, a set of schemes for QKD [2][3][4][5][6], direct secure quantum communication [7][8][9][10][11][12][13][14][15], and its controlled counterpart-controlled deterministic secure quantum communication (CDSQC) [16,17], have been proposed in the recent past (see [18] for a review). A recent addition to this long list is quantum e-commerce [19][20][21][22][23][24].…”