Quantum-noise randomized ciphers

Ranjith Nair*, Horace P. Yuen, Eric Corndorf, Takami Eguchi, Prem Kumar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


We review the notion of a classical random cipher and its advantages. We sharpen the usual description of random ciphers to a particular mathematical characterization suggested by the salient feature responsible for their increased security. We describe a concrete system known as αη and show that it is equivalent to a random cipher in which the required randomization is affected by coherent-state quantum noise. We describe the currently known security features of αη and similar systems, including lower bounds on the unicity distances against ciphertext-only and known-plaintext attacks. We show how αη used in conjunction with any standard stream cipher such as the Advanced Encryption Standard provides an additional, qualitatively different layer of security from physical encryption against known-plaintext attacks on the key. We refute some claims in the literature that αη is equivalent to a nonrandom stream cipher.

Original languageEnglish (US)
Article number052309
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number5
StatePublished - 2006

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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