Symmetric Ciphers

Question 1

AES

Answer 1

Key: 128, 192, 256
Block: 128 bit
Rnds: 10 (128), 12 (192), 14 (256) rounds
Algo: Substitution Permutation (Rijyndael)

Question 2

Serpent

Answer 2

Key: 128, 192, 256
Block: 128 bit
Rnds: 32 rounds
Algo: Substitution Permutation

Question 3

Twofish

Answer 3

Key: up to 256
Block: 128 bit
Rnds: 16 rounds
Algo: Feistel

Question 4

RC5/RC6

Answer 4

Key: up to 2048 bit
Block: 32, 64, 128
Rnds: up to 255 rounds
Algo:

Question 5

IDEA

Answer 5

Key: 128 bit
Block: 64 bit
Rnds: 8 rounds
Algo: Lai-Massey Scheme

Question 6

TEA

Answer 6

Key: 128 bit
Block: 64 bit
Rnds: 64 rounds
Algo: Feistel

Question 7

SHARK

Answer 7

Key: 128 bit
Block: 64 bit block
Rnds: 6 rounds
Algo:

Question 8

CAST

Answer 8

Key: 128 or 256 bit
Block: 64 bit
Rnds: 12 < 80 - 16 >80
Algo: PGP, 8 bit rounds

Question 9

Blowfish

Answer 9

Key: 32-448 bit
Block: 64 bit
Rnds: 16 rounds
Algo: Feistel, in BCrypt, CrashPlan, CryptoDisk, DriveCrypt

Question 10

DES

Answer 10

Key: 56 bit
Block: 64 bit
Rnds: 16 rounds
Algo: Feistel

Question 11

3DES

Answer 11

Key: 56
Block: 64 bit
Rnds: 16 rounds
Algo: Feistel
- DES 3 times

Question 12

Skipjack

Answer 12

Key: 80 bit
Block: 64 bit
Rnds: 32 rounds
Algo: Unbalanced Feistel
- NSA for Clipper Chip

Question 13

RCA (stream!)

Answer 13

Key: 1-256 bit
Block:
Rnds: up to 255 rounds
Algo:

Question 14

RC4 (stream!)

Answer 14

Key: 40 bit minimum recommended
Rnds: 1 round
- weak stream cipher, used in SSL/web/wifi security
- RFC7465 prohibits use in TLS

Question 15

Fish (stream!)

Answer 15

• lagged fibonacci pseudorandom number generator
• data stream XORed with the key
• FISH improvement

Question 16

Pike (stream!)

Answer 16

• revised version of FISH to address known plaintext attack vulnerabilities
• most widely used stream cipher