Appendices

Essential cryptography terms

Encryption is a process of transforming simple text/data, called plaintext, into unintelligible form, named as ciphertext. Decryption is the inverse process of encryption.

A key is a secret string of characters or symbols that is used for the encryption/decryption of plaintext/ciphertext.

Cipher is an algorithm that performs encryption/decryption. Sometimes, the term cryptosystem is used instead of cipher. There are two types of ciphers depending on the use of keys: symmetric and asymmetric.

Symmetric ciphers, also referred as secret-key ciphers, use the same key for encryption and decryption. Symmetric cryptosystems are divided into two groups: block and stream ciphers. In block ciphers, operations of encryption/decryption are performed on blocks of bits or bytes, whereas stream ciphers operate on individual bits/bytes.

Asymmetric ciphers, alternatively named public-key ciphers, use two keys, one for encryption and other for decryption.

Cryptanalysis is a study of techniques for “cracking” encryption ciphers, i.e., attacks on cryptosystems.

Hashing algorithms involves taking an input of any length and outputting a fixed-length string, called a hash. Which can be used, for example, as signatures or for data-integrity purposes.