FUNDAMENTALS OF COMPUTER

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 block cipher works on a single character at a time, and is faster than a stream cipher. An asymmetric encryption key that does have to be protected. An algorithm that takes one character and replaces it with one character.

Detailed explanation-3: -Stream cipher relies on substitution techniques like Caesar cipher, modified Caesar cipher, monoalphabetic cipher, homophonic cipher, polygram substitution cipher, polyalphabetic cipher, Playfair cipher, and hill cipher.

Detailed explanation-4: -A substitution cipher takes each character (sometimes groups of characters) in a message and replaces it with a different character according to fixed rules. Every occurrence of one character will be substituted with the same replacement character.

Detailed explanation-5: -A substitution cipher is one in which letters are represented by other letters; it can be deciphered by someone knowing the order of the cipher alphabet used. One method of hiding messages in this way was invented by Julius Caesar, Roman Emperor over two thousand years ago. It is known as the Caesar cipher.