Chapter 20

Question 1

Conventional encryption
Secret-key or single-key
- plaintext
- encryption algorithm
- secret key
- ciphertext
- decryption algorithm

Answer 1

Symmetric Encryption

Question 2

Type of operations used for plaintext > ciphertext

• # of keys used
• Way in which plain text is processed

Answer 2

Cryptography

Question 3

• Encryption is computationally secure if:
• cost to break exceeds info
• time to break exceeds lifetime of info

Answer 3

Computationally Secure Encryption Schemes

Question 4

Symmetric block cipher consists of:

• sequence of rounds
• substitutions & permutations controlled by key

Answer 4

Block cipher structure

Question 5

FIPS PUB 46

Algorithm is referred to as Data Encryption Algorithm (DEA)

Answer 5

Data Encryption Standard (DES)

Question 6

DES FIPS PUB 46-3

Decryption same with keys reversed

Answer 6

Triple DES (3DES)