ABSTRACT
Classical cryptography focuses on writing and transmission of information and corresponding deciphering methods. The development of modern cryptography has promoted the development of computer science, especially the need for computer and network security. Cryptography has been applied in daily life, including ATM chips, computer access passwords, e-commerce, and other spheres. Hash functions are often referred to as cryptographic hash functions, for example, message digest functions, which do not necessarily use keys, but are associated with many important cryptographic algorithms. Symmetric key encryption is an encryption method in cryptography. In symmetric key cryptography, encryption and decryption use the same key, and perhaps different keys are used for different messages, but they all face the challenge of key management. The difference between blockchains and other decentralized peer-to-peer systems is that it provides users with financial and economic incentives to complete a job.
