Given below are two statements:
Statement I: In Ceaser Cipher each letter of plain text is replaced by another letter for encryption.
Statement II: Diffic-Hellman algorithm is used for exchange of secret key.
In the light of the above statements, choose the correct answer from the options given below:

Correct option is A

Statement I: "In Caesar Cipher, each letter of plaintext is replaced by another letter for encryption."
This statement is correct. In the Caesar Cipher, each letter of the plaintext is shifted by a certain number of positions in the alphabet to create the ciphertext. It is a simple substitution cipher and each letter is indeed replaced by another letter.
Statement II: "Diffie-Hellman algorithm is used for exchange of secret key."
This statement is correct. The Diffie-Hellman algorithm is a key exchange protocol that allows two parties to securely share a secret key over an insecure channel. This secret key can then be used for symmetric encryption in further communication.
Information Booster:
1. Caesar Cipher: The Caesar cipher is one of the oldest and simplest encryption techniques. It is a substitution cipher, where the letters of the alphabet are shifted by a fixed number, known as the key. Although historically significant, it is now considered insecure because the shift is easily guessable and can be cracked with brute-force methods. It’s often used today for educational purposes.
2. Diffie-Hellman Algorithm: Diffie-Hellman is used to securely exchange cryptographic keys over a public channel. It enables two parties to each generate a shared secret key that is never directly transmitted, making it highly useful for secure communications. Although it allows for secure key exchange, Diffie-Hellman itself is vulnerable to man-in-the-middle attacks if not properly implemented with authentication.
3. Substitution Cipher: In the case of the Caesar cipher, the technique is an example of a substitution cipher where each character is replaced by another based on a fixed position.
4. Key Exchange: Diffie-Hellman’s major contribution is in allowing two parties to establish a shared secret without actually exchanging the secret itself over the insecure channel.