COMPUTER NETWORKING

Detailed explanation-1: -Substitution Ciphers. Substitution ciphers encrypt the plaintext by swapping each letter or symbol in the plaintext by a different symbol as directed by the key. Perhaps the simplest substitution cipher is the Caesar cipher, named after the man who used it.

Detailed explanation-2: -A substitution cipher replaces each letter in the message with a different letter, following some established mapping.

Detailed explanation-3: -The Caesar cipher is a classic example of ancient cryptography and is said to have been used by Julius Caesar. The Caesar cipher is based on transposition and involves shifting each letter of the plaintext message by a certain number of letters, historically three, as shown in Figure 5.1.

Detailed explanation-4: -A substitution cipher is a type of encryption where characters or units of text are replaced by others in order to encrypt a text sequence. Substitution ciphers are a part of early cryptography, predating the evolution of computers, and are now relatively obsolete.