DES, AES, RSA

Question 1

What is the DES block size in bits?

Answer 1

The block size is 64 bits.

Question 2

What is the DES key size in bits?

Answer 2

64 bits, 56 of which are the key, 8 bits are a parity check

Question 3

How many rounds does DES have

Answer 3

16 rounds – each uses a different 48 bit key generated from the 56 bit key

Question 4

What are the rules for one-time pads? <4>

Answer 4

• The key is at least as long as the plaintext
• The key is truly random
• Each key is used only once
• There should only be two copies of the key:
one for the sender and one for the receiver