ABSTRACT
Cryptography is a word derived from the Greek that is approximately translated as hidden writing. There are various forms and styles of cryptography; however, since ancient times the aim of cryptography has been the same: secure the transmission of information from an emitter to a receiver. A classical form of cryptography involves the sharing of a code between the emitter and the receiver. A different algorithmic approach allows the use of a public key and is known as public key cryptography. This approach uses a public key and a secured key, both of which are mathematically connected. Quantum cryptography was first introduced by Weisner in 1983 and then by C. H. Bennett and G. Brassard. A refined protocol was introduced by Bennett et al. The Bennett and Brassard approach relies on the straightforward polarization property of single photons. An alternative method, based on the quantum entanglement of pairs of photons, was introduced by A. K. Ekert.
