The character shifting method known as Caesar cipher is categorized as what type of cipher?

The Caesar cipher is categorized as a substitution cipher because it operates by replacing each letter in the plaintext with a letter found a fixed number of positions down the alphabet. For example, with a shift of three, the letter A would be replaced by D, B by E, and so on, wrapping around to the beginning of the alphabet as necessary. This straightforward method of modifying characters clearly aligns with the principles of substitution ciphers, where the identity of the characters is changed but the overall structure remains intact.

In contrast, symmetric encryption involves the use of the same key for both encryption and decryption processes, which is a broader category encompassing various encryption techniques, beyond simple character shifting. Block ciphers operate on fixed-size blocks of data and employ complex algorithms for encryption, while hash functions are designed to take input data and produce a fixed-size string of characters, which is generally irreversible. Thus, the classification of the Caesar cipher as a substitution cipher highlights its fundamental mechanism of character replacement, distinguishing it from these other cryptographic methods.