Quantum and Post-Quantum CryptographyRecent years have prompted research intoquantum computers. Quantum computers have been the subject of controversy dueto their abilities to solve complex mathematical phenomena that have beenprimarily developed as the basis of information encryption .

Given that theselarge quantum computers are built, they shall inevitably compromise the keycryptosystem that is currently in use. This would jeopardize theconfidentiality presently enjoyed by digital communication and internet usersworldwide. The primary objective of post-quantum cryptography is to createcryptographic systems that can interoperate with existing communicationprotocols. This paper shall look into common cryptographic topics and reflectthe effect of post cryptographic quantum computing on common informationencryption. Quantum key distribution Quantum key distribution is indeed asuccessful application to cryptography, quantum information that utilizes the quantummechanics theory to secure data (Quantum.ukzn.

ac.za.). Quantum keydistribution generates a random key between two points over an insecurenetwork. Quantum key distribution is founded the superposition principle andthe Heisenberg’s principle.

A one- timepad encryption scheme is created and implemented using the securely distributedquantum key. A great protocol of quantumkey distribution is the “BB84” protocol in which single qubits arechosen randomly from {???, ???, ???, ???} states and sent. For QKDthe key used for encryption should only be used once. This removes the chancesof prediction from an eavesdropper or from the sender/receiver. Hence Quantumkey distribution guarantees integrity over an insecure channel unlike inpost-quantum cryptography whose key algorithms’ security rely on toughmathematical problems and the capability of a quantum computer, one that ideallyruns Shor’s algorithm, to solve them these problems. Symmetric cryptography & Symmetric keymanagement systems and protocols Cryptographyinvolves the process of making messages non-readable by encypting them withdifferent algorithms.

Cryptographic algorithms are grouped into two types ofencryption: symmetric and asymmetric encryption.In Symmetric encryption asingle key is used for the encryption and decryption proccess. A crucial problem thatlies in symmetric key cryptography is the distribution of the secret key. Thekey distribution must happen secretly.

However key sharing can happen in onesome ways; a trusted third party could get involved in sharing the key with therecipient. Alternatively, the sender can physically deliver the key to thereceiver. If the sender and reciever have previously used a key, they cancommunicate the new key through encryption using the old key. Nonetheless thisoption of distribution is hazardous because of the fact that an eavesdroppercan gain access to the old key and acquire the new key by interceptingcommunication of the new key Hash functionsA cryptographic hashfunction receives a message as input and produces what is known as a messagedigest of predetermined fixed length. One property of a cryptographic hashfunction is that the digest from the hash function for any given message is impossibleto compute for those with a given hash. Another property of the cryptographic functionshave is uniqueness There are collisions of hash functions put the probabilityis low 1?e/(?k(k?1)/2N). However with the development of quantum computers, itis very likely that using the hash value, the initial message could be computedand derived successfully.

This would in a high magnitude compromise theintegrity of information passed over an insecure channel. Other practicalapplications that use hash functions such as digital signatures andauthentication also face an integrity threat following the developmentpost-quantum cryptography. Public keycryptography Public keycryptography also known as asymmetric encryption uses two non-identical forcommunication. The two keys involved are a public and a public key. Each ofthese two keys have different roles; the public key encrypts the message whilethe private key decrypts the message. Private keys can however not be computedfrom public keys. Public keys are therefore shared hence allowing users aconvenient content encryption platform. Given that the public keys have to beshared for decryption and encryption to take place , they are therefore stored withindigital certificates to facilitate structured and secure sharing amongcommunicators.

Users, therefore, have them at their disposal for encryptionduring information sharing. However, only the users of private keys can decryptthe information.Shor’s algorithm Shor’salgorithm was developed by a mathematician known as Peter Shor. His innovationbrought about a quantum algorithm for integer factorization. All it takes is one post cryptography quantummachine with enough qubits to solve quantum gates for 0((log N) 2(log log N) (log log log N)). For this reason, therefore, these quantum computers canbreak public key cryptography which is based on Shor’s algorithm.

The public key encryption is pegged on aprinciple huge numbers are computationally impractical. This phenomenon is however only valid forclassic computers. The development of quantum computers withstanding, softwaredevelopers need to reach common ground with mechatronic engineers in developingcomputing systems that shall not compromise the integrity of informationreliance and computing.