Cryptography and Quantum Computing

2436 Words10 Pages
Cryptography and quantum computing Cryptography is a primal art that has passed through numerous paradigms, from simple letter substitutions to polyalphabetic substitutions to rotor machines to digital encryption to public-key cryptosystems. With the possible initiation of quantum computers and the out of the ordinary behaviours they exhibit, a new paradigm shift in cryptography may be on the scope. Quantum computers may hold the potential to make most modern encryption useless against a quantum-enabled adversary. [6] The term cryptography refers to the art or science of designing cryptosystems. The main function of cryptography is to protect the interests of parties communicating in the presence of adversaries. A cryptosystem is a mechanism or scheme engaged for the purpose of providing such protection. [6] Symmetric-key, cryptography is characterized by the use of one key, kept undisclosed that both parties in communication use to encrypt and decrypt messages. Modern symmetric-key cryptosystems come in two main favours: stream ciphers and block ciphers. A stream cipher operates on smaller units often just one byte or one bit at a time and produces an output stream in which the encryption of each unit of cipher text depends on the sequence of units for some length before it. Where else a block cipher operates on larger blocks of text often 64-bit blocks, performing a particular scrambling function on the block. A simple block cipher will always encrypt the same plaintext block to the same cipher text block; though more advanced techniques such as block chaining can reverse this effect. [12] The same piece of plaintext will generally encrypt to a different cipher text at different times. A stream cipher is abstractly very similar to a pseudorandom number generator and is often implemented in the same way. The main intention of such a cryptosystem is to prevent an

More about Cryptography and Quantum Computing

Open Document