November 25, 2021 | By devevon

Cryptography

Cryptography can be divided into classical and modern Cryptography. Classical Cryptography focus on confidential writing and transmission of information as well as the corresponding deciphering methods. Modern Cryptography is not only focusing on information confidentiality, but also involves information integrity verification, non-repudiation of information publication, and all information security issues generated by internal and external attacks in distributed computing.

The different between Classical Cryptography and Modern Cryptography is encoding and deciphering of classical cryptography usually relies on the creativity and skill of the designer and the adversary, and exists as a practical art. Modern Cryptography is base on a number of theories, and those theories are making modern cryptography a science that can be studied systematically and rigorously.

Classical Cryptography

Classical Cryptography is one type of cryptography, many of which use alternating or transposition ciphers, or sometimes a combination of the two. Usually the cyrpto will be a classic password is based on A pinyin letter (like A-Z), a manual operation, or a simple device.

Examples of classical cryptography

Alberti ADFGVX ROT13 Two-square

Modern Cryptography

Modern cryptography attaches great importance to the research and application of block cipher and stream cipher. Block ciphers are, in a sense, a modernization of Alberti’s multi-character encryption. Block cipher takes a block of plaintext and a key and outputs a ciphertext block of the same size. Since messages are often longer than a single block, there are ways to weave contiguous blocks together.

Example of modern cryptography

RSA ElGamal MD5 SHA-256