This chapter is an analysis of commercial quantum key distribution systems. Upon analysis, the generalized structure of QKDS with phase coding of a photon state is presented. The structure includes modules that immediately participate in the task of distribution and processing of quantum states. Phases of key sequence productions are studied. Expressions that allow the estimation of physical characteristics of optoelectronic components, as well as information processing algorithms impact to rate of key sequence production, are formed. Information security infrastructure can be utilized, for instance, to formulate requirements to maximize tolerable error level in quantum channel with a given rate of key sequence production.
Top1. Quantum Key Distribution
Quantum Cryptography (QC) is a part of quantum computing that examines the methods of information security by using a quantum carrier (Kilin, Nizovtsev, & Horoshko, 2007; Scarani, 2006; Bouwmeester, Ekert, & Zeilinger, 2000; Gisin, Ribordy, Tittel, & Zbinden, 2002; Rumyantsev, 2010). QC proposes a new method of generating random private keys for quantum communication line users. Its privacy and eavesdropping protection is based upon quantum principles instead of Classical Cryptography (CC) methods (Kotenko, & Rumiantsev, 2009; Mao, 2003; Smart, 2004; Singh, 2000; Brassard, 2007) used now and based upon mathematical law, which can be cracked.
Quantum key distribution (QKD) is a technology based upon quantum principles for generation random bit strings, which could be used as privacy keys, between two remote users.
The hardware is the realization of the process of sending and receiving data, for example, a single photon used in a fiber link. An eavesdropping changes the influential parameters of the physical objects, which used as data carrier.
QC is permitted to generate random keys for two users, which has no shared confidential data initially, and that key will be unknown for eavesdroppers.
The quantum physics law starts influence when data transmission uses signals containing average photon number less than 0.1 instead of the signals containing many thousands of photon. The nature of QC privacy is based on this law in conjunction with CC procedures. One of these laws is Heisenberg's uncertainty principle, and in accordance with it, a trial measurement of a quantum state changes to an initial state
The main gain of QC is that eavesdropping will be known to legal users, besides of absolute privacy.
Indivisible quantum and entanglement are very specific features of quantum physics (Kilin, Nizovtsev, & Horoshko, 2007; Scarani, 2006; Bouwmeester, Ekert, & Zeilinger, 2000; Gisin, Ribordy, Tittel, & Zbinden, 2002). QC uses both of these features.
The necessity in symmetric encryption systems arises in process of data transmission for reducing economic and social risks.