COMPUTER FUNDAMENTALS

Detailed explanation-1: -The Caesar Cipher is a monoalphabetic rotation cipher used by Gaius Julius Caesar. Caesar rotated each letter of the plaintext forward three times to encrypt, so that A became D, B became E, etc., as shown in Table 4.6. Table 4.7 shows how “ATTACK AT DAWN” encrypts to “DWWDFN DW GDZQ” using the Caesar Cipher.

Detailed explanation-2: -The first encryption was the substitution cipher which used a very simple method of replacing units (letters or groups of letters) with other units based on a set of substitution rules, e.g., A=N, B=O, etc. Before computers, the security of encryption was ensured by keeping cipher keys with the sender and receiver.

Detailed explanation-3: -The “Caesar Box, ‘’ or “Caesar Cipher, ‘’ is one of the earliest known ciphers. Developed around 100 BC, it was used by Julius Caesar to send secret messages to his generals in the field. In the event that one of his messages got intercepted, his opponent could not read them.

Detailed explanation-4: -The first cipher device appears to have been employed by the ancient Greeks around 400 bce for secret communications between military commanders. This device, called the scytale, consisted of a tapered baton around which was spirally wrapped a piece of parchment inscribed with the message.

Detailed explanation-5: -It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on.