The confidentiality of the spectral implementation of the Y00 quantum encryption protocol is investigated, against ciphertext only and known plaintext attacks. A generic framework is proposed for developing a secure encryption scheme based on a single multiport encoder/decoder.
Abstract As past works have shown, information‐theoretically secure implementations transmitters of Y00 quantum noise randomised cypher are possible. An advance to the provably secure Y00 protocol by bridging gaps between experimental results and theoretical analyses under so‐called quantum collective measurement attacks with known plaintexts is aimed. It would be the strongest attack on the Y00 protocol in the context of quantum key distribution protocols. However, recently proposed security evaluations under the attacks were too abstract to apply to experiments. Therefore, security analyses directly evaluable with the equipped Y00 transmitters under attack are offered. Thus, new security indices are proposed instead of ordinary security measures, such as the bit‐error‐rate guarantee between optical signals or a masking size. Contrarily, unsolved problems are also listed.
A novel implementation of quantum-noise optical cryptography is proposed, which is based on a simplified architecture that allows long-haul, high-speed transmission in a fiber optical network. By using a single multiport encoder/decoder and 16 phase shifters, this new approach can provide the same confidentiality as other implementations of Yuen's encryption protocol, which use a larger number of phase or polarization coherent states. Data confidentiality and error probability for authorized and unauthorized receivers are carefully analyzed.
We study in detail the problem of encryption of quantum information. We present an attack on a private quantum channel (PQC) which applies when partial classical description of a ciphertext is known (the so-called known-ciphertext attack) and we show how this situation can be avoided. The quantum analogue of the known plaintext attack is also discussed. We determine how correlations between quantum systems can be encrypted and we conclude that two PQCs on the subsystems form a PQC on the whole composite system. Finally, some applications of the PQC are suggested and a security of a noisy channel is discussed.
It is shown that the security, against known-plaintext attacks, of the Yuen 2000 (Y00) quantum-encryption protocol can be considered via the wire-tap channel model assuming that the heterodyne measurement yields the sample for security evaluation. Employing the results reported on the wire-tap channel, a generic framework is proposed for developing secure Y00 instantiations. The proposed framework employs a dedicated encoding which together with inherent quantum noise at the attacker's side provides Y00 security.