Use of different algorithm types

Question 1

Use of symmetric algorithms

Answer 1

• bulk encryption

- encrypting large amounts of data

Question 2

Use of asymmetric algorithms

Answer 2

• distribution of symmetric keys (shared key)
• identity authentication via digital signatures + certificates
• non-repudiation services + key agreement

Question 3

Use of hash functions

Answer 3

• verification of digital signatures
• generation of pseudo-random numbers
• integrity services (data integrity + authenticity)

Question 4

Hash / Symmetric / Asymmetric

• number of keys

Answer 4

Hash = 0
Symmetric = 1
Asymmetric = 2+

Question 5

Hash / Symmetric / Asymmetric

• recommended key length (NIST)

Answer 5

Hash = 256 bits
Symmetric = 128 bits
Asymmetric = 2048 bits

Question 6

Hash / Symmetric / Asymmetric

• common example

Answer 6

Hash = SHA
Symmetric = AES
Asymmetric = RSA

Question 7

Hash / Symmetric / Asymmetric

• Speed

Answer 7

Hash = Fast
Symmetric = Fast
Asymmetric = Slow

Question 8

Hash / Symmetric / Asymmetric

• complexity

Answer 8

Hash = medium
Symmetric = medium
Asymmetric = high

Question 9

Hash / Symmetric / Asymmetric

• Effect of Key compromise

Answer 9

Hash = n.a.
Symmetric = Loss of both (sender & receiver)
Asymmetric = Loss of owner of the asymmetric key only

Question 10

Hash / Symmetric / Asymmetric

• Key management & Sharing (easy or not?)

Answer 10

Hash = n.a.
Symmetric = Challenging
Asymmetric = Easy & Secure

Question 11

Hash / Symmetric / Asymmetric

• Examples

Answer 11

Hash = SHA-224, SHA-256, SHA-384, SHA-512
Symmetric = AES, Blowfish, Twofish, 3DES, RC4
Asymmetric = RSA, DSA, ECC, Diffie-Hellman