An idea of Stephen Wiesner [1] is expanded to give a method of public key distribution which is provably secure under the principles of quantum mechanics. It appears that this scheme could actually be implemented in favorable environments.
During the Cold War, a revolutionary cryptographic method, quantum cryptography, emerged. Grounded in the laws of quantum physics, quantum cryptography ensures absolute security using quantum principles. Stephen Wiesner introduced the concept in 1983, but initially received little attention, as technology at the time did not allow the encryption method to be put into practice. The field of quantum cryptography began to take shape with the arrival of two more researchers, Giles Brassard and Charles Bennett. The development of quantum cryptography accelerated dramatically after Artur Ekert proposed the application of Bell’s theorem in this field. Afterwards, more researchers got involved and new theorems and applications were developed, leading the field to become a major subject at the forefront of physics research. This paper explores why quantum cryptography is exceptionally secure and the steps that brought this idea to practice. The paper looks into the intriguing concept of quantum cryptography and the stimulating stories surrounding its progress. From Stephen Wiesner’s original proposal through Brassard and Bennett’s persistent efforts to the exciting debates between Ekert and Brassard and Bennett. This paper highlights the significant milestones and achievements that have positioned quantum cryptography at the forefront of physics research.
It all begun by the early 1970s through, the work of Stephen Wiesner and Gilles Brassard, who introduced the concept of quantum conjugate coding, and it has now stretched to a level where today's agile communication systems constitute a substantial challenge for data security and safety. A number of research has been performed to achieve secure communication among legitimate parties in which QKD (Quantum Key Distribution) is prominent. Quantum Key Distribution (QKD), also called Quantum Cryptography, enables two communicating parties to share secret cryptographic keys with security that is theoretically guaranteed by the laws of quantum mechanics, assuming ideal conditions. However, practical implementations may be vulnerable to certain attacks, and the security of QKD can be compromised by imperfections in hardware, side-channel attacks, or limitations in real-world setups. In a practical QKD setup, two stations send and receive encoded quantum particles and some classical information. The most rudimentary and well-known QKD protocol is BB84, developed by Bennet and Brassard in 1984. We have developed the simulation and achieved the secret shared key with and without an intruder.
The fates of SIGACT News and Quantum Cryptography are inseparably entangled. The exact date of Stephen Wiesner's invention of "conjugate coding" is unknown but it cannot be far from April 1969, when the premier issue of SIGACT News ---or rather SICACT News as it was known at the time---came out. Much later, it was in SIGACT News that Wiesner's paper finally appeared [74] in the wake of the first author's early collaboration with Charles H. Bennett [7]. It was also in SIGACT News that the original experimental demonstration for quantum key distribution was announced for the first time [6] and that a thorough bibliography was published [19]. Finally, it was in SIGACT News that Doug Wiedemann chose to publish his discovery when he reinvented quantum key distribution in 1987, unaware of all previous work but Wiesner's [73, 5].Most of the first decade of the history of quantum cryptography consisted of this lone unpublished paper by Wiesner. Fortunately, Bennett was among the few initiates who knew of Wiesner's ideas directly from the horse's mouth. His meeting with the first author of this column in 1979 was the beginning of a most fruitful lifelong collaboration. It took us five more years to invent quantum key distribution [4], which is still today the best-known application of quantum mechanics to cryptography. The second author joined in slightly later, followed by a few others. But until the early 1990's, no more than a handful of people were involved in quantum cryptographic research. Since then, the field has taken off with a vengeance, starting with Artur K. Ekert's proposal to use quantum nonlocality for cryptographic purposes [33].The golden age started in earnest when Ekert organized the first international workshop on quantum cryptography in Broadway, England, in 1993. Since then, many conferences have been devoted at least partly to quantum cryptography, which has become a major international topic. The purpose of the aforementioned 1993 bibliography in SIGACT News was to cite as much as possible all papers ever written on the subject, including unpublished manuscripts: there were 57 entries in total. Today, such an undertaking would be nearly impossible owing to the explosion of new research in the field.The purpose of this column is to give an overview of the current research in quantum cryptography. It is not our intention to be exhaustive and we apologize in advance to any researcher whose work we may have omitted. Note that we do not necessarily agree with the claims in every paper mentioned here: this column should not be construed as a seal of approval!