Week 1 - Modern Block Ciphers

Question 1

What is S-Box cypher? (substitution box)

Answer 1

replace a block of data with another block of data to achieve CONFUSION.

done through a lookip table, specific input bits determine the output value

Question 2

What is P-Box cypher? (permutation box)

Answer 2

bits are rearranged, repeated, discarded but not changed to achieve DIFFUSION

Question 3

What are the three types of P-boxes?

Answer 3

1, Compression P-box - discards some bits
2, Straight P-Box - reorders some bits
3, Expansion P-box - repeats some bits

Question 4

What are the three key components of modern block symmetric cyphers?

Answer 4

• Substitution boxes (S-boxes)
• permutation boxes (P-boxes)
• key schedules.

Question 5

What is a key schedule?

Answer 5

an algorithm which takes a key and generates subkeys for use in rounds