Cryptographic terminology

Until modern times, cryptography almost exclusively refers to encryption algorithms: the process of transforming ordinary information (plaintext) into incomprehensible data (ciphertext); Decryption algorithm is the opposite process: from ciphertext to plaintext; Passwords include these two algorithms. Generally speaking, encryption refers to encryption and decryption technology. The specific operation of the cipher machine is determined by two parts: one is the algorithm, and the other is the key. A key is a secret parameter used in cryptographic algorithms, which is usually only owned by the communicator. Historically, keys were usually used directly on cryptographic machines without authentication or integrity testing. Cryptanalysis is a subject that studies how to crack cryptography. But in practical use, it is usually called cryptography (in English, it is usually called cryptography), and its meaning is not specifically distinguished.

In spoken language, code usually refers to various methods of encrypting or hiding information. However, in cryptography, encoding has a more specific meaning: it means replacing a specific plaintext with a codeword. For example, replace "(attack at dawn)" with "(apple pie)". Coding is no longer used in strict cryptography, but it has a clearer meaning in information theory or communication principle.

In spoken Chinese, personal account passwords used by computer systems or networks are often replaced by passwords. Although the password also belongs to the scope of cryptography research, it is not the same as the key in cryptography academically, although the two are often closely related.