Per-Round Key Generation Initial Permutation of deS key Ci1 28 bits i-1 28 bits Circular Left Shift Circular Left shift One round Permutation Round1,2,9,16 with discard single shift Others: two bits 48 bits K Ci 28 bits Di 28 bits 2424 Per-Round Key Generation 28 bits 28 bits 48 bits Ki One round Circular Left Shift Circular Left Shift 28 bits 28 bits Permutation with Discard Initial Permutation of DES key C i-1 D i-1 C i D i Round 1,2,9,16: single shift Others: two bits