|
Quantum cryptography is the science of exploiting quantum mechanical properties to perform cryptographic tasks. The best known example of quantum cryptography is quantum key distribution which offers an information-theoretically secure solution to the key exchange problem. Currently used popular public-key encryption and signature schemes (e.g., RSA and ElGamal) can be broken by quantum adversaries. The advantage of quantum cryptography lies in the fact that it allows the completion of various cryptographic tasks that are proven or conjectured to be impossible using only classical (i.e. non-quantum) communication (see below for examples). For example, It is impossible to copy data encoded in a quantum state and the very act of reading data encoded in a quantum state changes the state. This is used to detect eavesdropping in quantum key distribution. == History == Quantum cryptography was proposed first by Stephen Wiesner, then at Columbia University in New York, who, in the early 1970s, introduced the concept of quantum conjugate coding. His seminal paper titled "Conjugate Coding" was rejected by IEEE Information Theory Society, but was eventually published in 1983 in SIGACT News (15:1 pp. 78–88, 1983). In this paper he showed how to store or transmit two messages by encoding them in two "conjugate observables", such as linear and circular polarization of light, so that either, but not both, of which may be received and decoded. He illustrated his idea with a design of unforgeable bank notes. In 1984, building upon this work, Charles H. Bennett, of the IBM's Thomas J. Watson Research Center, and Gilles Brassard, of the Université de Montréal, proposed a method for secure communication based on Wiesner’s "conjugate observables", which is now called BB84.〔Bennett, C.H. and G. Brassard. Quantum cryptography: Public key distribution and coin tossing. In Proceedings of IEEE International Conference on Computers, Systems and Signal Processing, volume 175, page 8. New York, 1984.〕 In 1990 Artur Ekert developed a different approach to quantum key distribution based on peculiar quantum correlations known as quantum entanglement.〔Ekert. A. Physical Review Letters, 67, pp.661-663, (1991)〕 Random rotations of the polarization by both parties (usually called Alice and Bob) have been proposed in Kak's three-stage quantum cryptography protocol.〔Kak, S., A three-stage quantum cryptography protocol. Foundations of Physics Letters, vol. 19, pp.293-296, 2006.〕 In principle, this method can be used for continuous, unbreakable encryption of data if single photons are used.〔Chen, Y. et al., Embedded security framework for integrated classical and quantum cryptography in optical burst switching networks. Security and Communication Networks, vol. 2, pp. 546-554, 2009.〕 The basic polarization rotation scheme has been implemented.〔http://www.kurzweilai.net/a-multi-photon-approach-to-quantum-cryptography〕 The BB84 method is at the basis of quantum key distribution methods. Companies that manufacture quantum cryptography systems include MagiQ Technologies, Inc. of Boston, ID Quantique of Geneva, Switzerland, (QuintessenceLabs ) (Canberra, Australia) and (SeQureNet ) (Paris). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「quantum cryptography」の詳細全文を読む スポンサード リンク
|