Answer:
The correct answer is B. Cipher.
Explanation:
Cipher is a system of reversible transformations that depends on some secret parameter, called key, and is designed to ensure the secrecy of transmitted information.
The cipher can be a combination of conventional characters or an algorithm for converting ordinary numbers and letters. The process of making a message secret with a cipher is called encryption. An important parameter of any cipher is the key - a parameter of the cryptographic algorithm, which ensures the selection of one transformation from the set of transformations possible for this algorithm. In modern cryptography, it is assumed that all the secrecy of a cryptographic algorithm is concentrated in the key.
