The technique of moving a given letter a fixed number of spaces to the right or left is called what?

The technique of moving a given letter a fixed number of spaces to the right or left is referred to as a substitution cipher, commonly identified as a Caesar cipher in its simplest form. This method involves replacing each letter in the plaintext with another letter a fixed number of positions down the alphabet.

In this context, "Single substitution" accurately describes the process because each letter is shifted individually based on a consistent rule, which can be a specified number of spaces in the alphabet. This single substitution mechanism maintains simplicity and is easy to understand and implement, forming a foundational concept in classical encryption techniques.

Other terms mentioned, such as "Multi substitution," generally refer to more complex ciphers that use varying substitution rules for different letters, which does not apply to the fixed shifting method being described. "Bit shifting" pertains to binary operations used in digital circuits and is not relevant to letter substitution. "Confusion" is a term used in cryptography to describe techniques that obscure the relationship between the key and the ciphertext but does not specifically describe the act of shifting letters.