Compare Papers
Paper 1
The Universal Composable Security of Quantum Message Authentication with Key Recyling
Patrick Hayden, Debbie W. Leung, Dominic Mayers
- Year
- 2016
- Journal
- arXiv preprint
- DOI
- arXiv:1610.09434
- arXiv
- 1610.09434
Barnum, Crepeau, Gottesman, Tapp, and Smith (quant-ph/0205128) proposed methods for authentication of quantum messages. The first method is an interactive protocol (TQA') based on teleportation. The second method is a noninteractive protocol (QA) in which the sender first encrypts the message using a protocol QEnc and then encodes the quantum ciphertext with an error correcting code chosen secretly from a set (a purity test code (PTC)). Encryption was shown to be necessary for authentication. We augment the protocol QA with an extra step which recycles the entire encryption key provided QA accepts the message. We analyze the resulting integrated protocol for quantum authentication and key generation, which we call QA+KG. Our main result is a proof that QA+KG is universal composably (UC) secure in the Ben-Or-Mayers model (quant-ph/0409062). More specifically, this implies the UC-security of (a) QA, (b) recycling of the encryption key in QA, and (c) key-recycling of the encryption scheme QEnc by appending PTC. For an m-qubit message, encryption requires 2m bits of key; but PTC can be performed using only O(log m) + O(log e) bits of key for probability of failure e. Thus, we reduce the key required for both QA and QEnc, from linear to logarithmic net consumption, at the expense of one bit of back communication which can happen any time after the conclusion of QA and before reusing the key. UC-security of QA also extends security to settings not obvious from quant-ph/0205128. Our security proof structure is inspired by and similar to that of quant-ph/0205128, reducing the security of QA to that of TQA'. In the process, we define UC-secure entanglement, and prove the UC-security of the entanglement generating protocol given in quant-ph/0205128, which could be of independent interest.
Open paperPaper 2
Decoherence induced spin squeezing signatures in Greenberger-Horne-Zeilinger and W states
Kapil K. Sharma
- Year
- 2017
- Journal
- arXiv preprint
- DOI
- arXiv:1706.06273
- arXiv
- 1706.06273
We reckon the behaviour of spin squeezing in tripartite unsqueezed maximally entangled Green- berger-Horne-Zeilinger (GHZ) and W states under various decoherence channels with Kitagawa- Ueda (KU) criteria. In order to search spin squeezing sudden death (SSSD) and signatures of spin squeezing production we use bit flip, phase flip, bit-phase-flip, amplitude damping, phase damping and depolarization channels in the present study. In literature, the influence of decoherence has been studied as a destroying element. On the contrary here we investigate the positive aspect of decoherence, which produce spin squeezing in unsqueezed GHZ and W states under certain channels. Our meticulous study shows that GHZ state remain unsqueezed under aforementioned channels except bit-phase-flip and depolarization channels. While all the decoherence channels produce spin squeezing in W state. So we find, GHZ is more robust in comparison to W state in the sense of spin squeezing production under decoherence. Most importantly we find that none of the decoherence channel produce SSSD in any one of the state.
Open paper