Foundations of Cryptography

1. The basis of cryptography is the protection of the security of data and communications. It involves the use of algorithms and protocols to ensure that information is not accessed or tampered with by unauthorized persons or malicious parties during transmission and storage. The basic principles of cryptography include encryption and decryption, where encryption is the conversion of plaintext into ciphertext and decryption is the conversion of ciphertext back into plaintext.

2. Keys need to be updated frequently. Whenever a member leaves a user group, all the keys involving that member need to be updated.DES algorithm: published by the US government in 1977, DES is a 64-bit grouping cipher with an actual key length of 56 bits.

3. Quantum cryptography is a new type of cryptographic system based on quantum mechanics and cryptography, using the principles in quantum physics to realize cryptographic systems. Unlike the classical cryptographic systems mostly used at present, quantum cryptography utilizes the physical properties of the information carrier to realize it.

4, the theoretical basis of traditional cryptography is mathematics. Cryptography is the study of the technical science of preparing codes and deciphering codes. The study of the objective laws of cipher variation, as applied to the preparation of ciphers to preserve the secrets of communication, is known as coding.2, Cryptography is the art and science of encryption.