Step 1c: Create half-subkeys

• Sixteen each of Cn and Dn, 1 ? n ? 16

  • Each Ci, Di formed from Ci–1, Di–1 by 1 or 2 “rotate left” shifts

Iteration: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

# of shifts 1 1 2 2 2 2 2 2 1 2 2 2 2 2 2 1

• Example: Starting from C0 and D0

C0 = 1111000011001100101010101111

D0 = 0101010101100110011110001111

C1 = 1110000110011001010101011111

D1 = 1010101011001100111100011110

C2 = 1100001100110010101010111111

D2 = 0101010110011001111000111101

Previous slide

Next slide

Back to first slide

View graphic version