1. Define cryptography.
Cryptography is the use of mathematical operations to protect messages and convert them to unreadable format. 2. Which should be transmitted across the network—the plaintext or the ciphertext? Why or Why not?
Cipher text should be transmitted across the network to send the information from point A to point B due to confidentiality. Just in case if it get intercepted so they can’t understand the message.

3. What is a cipher?
A cipher is a specific mathematical process used in encryption and decryption.

4. What is a key?
It’s a random string of bits and it’s also the other thing that encryption and decryption requires.

5. What must be kept secret in encryption for confidentiality?
A key must be kept secret in encryption for confidentiality. As long as the key is secret both parties still have their confidentiality.

6. What is a cryptanalyst?
It’s someone who cracks encryption and it could be done by brute force key cracking. But as long as key is longer brute force key cracking will take longer time.

7. Complete the enciphering in Figure 3-2 of your textbook.
Cipher text: r w l y p j k n f c s d

8. Which leaves letters unchanged—transposition or substitution ciphers?
Transposition ciphers because it moves letter around the messages but letters itself doesn’t change. 9. Which leaves letters in their original positions—transposition or substitution ciphers?
Substitution Cipher because in this one character is substituted with other character but order of character doesn’t