Cryptology ePrint Archive: Report 2009/254

Improvement of One Quantum Encryption Scheme

Zhengjun Cao

Abstract: Zhou et al proposed a quantum encryption scheme based on quantum computation in 2006. Each qubit of the ciphertext is constrained to two pairs of conjugate states. So its implementation is feasible with the existing technology. But it is inefficient since it entails six key bits to encrypt one message bit, and the resulting ciphertext for one message bit consists of three qubits. In addition, its security can not be directly reduced to the well-known BB84 protocol. In this paper, we revisit it using the technique developed in BB84 protocol. The new scheme entails only two key bits to encrypt one message bit. The resulting ciphertext is just composed of two qubits. It saves about a half cost without the loss of security. Moreover, the encryption scheme is probabilistic rather than deterministic.

Category / Keywords: cryptographic protocols /

Date: received 1 Jun 2009

Contact author: zhencao at ulb ac be

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Version: 20090601:153331 (All versions of this report)

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