Quantum CryptographyINF-5219029945552Quantum cryptography is the newest technology in the field of encryption and has been proven to be the most secure to date. In this article, we will discuss what quantum cryptography is and what makes it the most secure and unbreakable.IntroductionAll our classical computer cryptography methods are basically based on mathematical calculations which are easy to implement in a sense but very difficult to treat in the other direction. . As RSA (Rivest-Shamir-Adleman) algorithm which is one of the first feasible and most famous public key cryptosystems, RSA is based on the large number factorization technique which makes it secure. The difficulty of factoring increases with the number of digits of the RSA key. For example, it would take millions of years to process a 128-digit number with today's computers. Classical cryptography still has limits, it is purely mathematical and the information cannot be separated from its physical representation. In classical physics, we use binary form to store and process data. In the 1980s, C. Bennet, P. Benioff, R. Feynman and others observed that very powerful new methods of information processing were possible with quantum mechanical systems. This gave rise to the concept of quantum computing. We have algorithms such as Shor's algorithm, a quantum computer can split a very large number into prime factors, which could take millions of years to solve. The day quantum cryptography becomes a reality, the RSA mentioned above will become insecure. Fortunately, we have an unbreakable code. According to Shannon's rules, if the data we are going to encrypt is much less than the key in length and the same key, we ...... middle of paper ...... Due notations: '+' represents a rectilinear pattern, 'X' represents a diagonal pattern '-' represents 0 (horizontal polarization quantum state) '/' represents 0 (45 degrees from the horizontal polarization state) '|' represents 1 (vertical polarization quantum state)'' represents 1 (45 degrees from the vertical polarization state). So, using the qubit representations above, a BB84 transmission for binary 11010011 might look like this: Alice: Bits 1 1 0 1 0 0 1 1Alice: Qubit ↕ ↕ ↔ ↕ ∕ ∕ ↕Bob: Diagram + XX + + XX +Bob: Qubit ↕ ↕ ↔ ∕ ↕Bob: Bits 1 1 1 1 0 0 1 1Key selection √ √ √ √ √Table 1 – Qubit transmission & binary digit selectionAlice sends the 1st 1 using the + scheme, the 2nd using scheme X, 1st 0 using scheme X and so on.BB84 Quantum Key Distribution ProtocolPractical problems with quantum cryptographyConclusion