Chapter 7: Cryptography - Cryptography Definitions and Concepts

Plaintext is the term used for readable data, whereas ciphertext is the data in its encrypted state. It is important to note that neither humans or machines should be able to properly read the data in its encrypted state. Only when the data is decrypted should it be able to be read by either human or machine. So, the process goes like this: plaintext is encrypted, and it becomes ciphertext. Then, in order to be read, the ciphertext is decrypted and becomes plaintext once again in order to read and used. Algorithms, a set of rules, are used to encrypt and decrypt data. A crptosystem is all of the things that make up an encryption and decryption process and should always be made up of software, protocols, algorithms, and keys. A key or crypto variable, is a single value that makes up a sequence of bits that are random. The algorithm that does the encryption and decryption should always be known, and only the keys should be kept secret. Bigger keyspaces allow for more possible keys, strengthening the encryption method. The one-time pad scheme is considered to be unbreakable if used in the right way. To work correctly, it must be constructed with truly random values, only used once, distributed securely, secured by the sender and the recipient, and must be as long as the message. This is a very basic description of how encryption works, and it does get more complicated than this.