Chapter 10

Question 1

2 types of cryptography:

Answer 1

• Symmetric cryptography
• Asymmetric cryptography

Question 2

Compare Transposition encryption and Substitution encryption:

Answer 2

Transposition encryption: The position of the character is changed but character’s identity is not changed

Substitution encryption: The character’s identity is changed while its position remains unchanged.

Question 3

Compare Monoalphabetic substitution and Polyalphabetic substitution:

Answer 3

• Monoalphabetic substitution: only incorporates a single alphabet in the encryption process. Ex: Caesar cipher.
• Polyalphabetic substitution: incorporates two or more alphabets in the encryption process. Ex: Vigenère cipher.

Question 4

Compare Stream Cipher and Block Cipher:

Answer 4

• Stream Cipher: plaintext is encrypted one character or bit at a time.
  Ex: Vigenère cipher, and RC4 stream cipher.
• Block Cipher: plaintext is divided into fixed-size blocks; each block is encrypted using the secret key.
  Ex: DES, and AES.

Question 5

What’s RSA algorithm and its phases?

Answer 5

a public key encryption technique and is considered the most secure way of encryption.

1- RSA Key Generation
2- RSA Encryption
3- RSA Decryption

Question 6

What’s hash function?

Answer 6

mathematical function which is used for mapping data into fixed-sized values.

Question 7

2 popular hashing algorithms:

Answer 7

• Message Digest Algorithm (MD): MD5, 128 bits
• Secure Hash Algorithm (SHA)

Question 8

What’s collision and collision resistance?

Answer 8

Collision: when two different inputs result in the same hash output.

Collision Resistance: when it’s computationally infeasible to find two inputs that produce the same hash value. It’s the strongest requirement.