E, D CT Block
n bits
PT Block
n bits
Canonical examples:
1. 3DES: n= 64 bits, k = 168 bits
2. AES: n=128 bits, k = 128, 192, 256 bits
Trang 3k1 k2 k3 kn
k 1
k 2
k 3
k n
Trang 4•
•
•
•
Trang 51 d n n
R L
R
Ld
R
L
R L
⊕
L
⊕
f
⋯ fd⊕
Trang 61 d n n
R
L
Ri L
⊕
Li-‐1 i(Li
R L
R
Ld
R
L
R L
⊕
L
⊕
f
⋯ fd⊕
Trang 71 d n n
R
L
Ri L
⊕
f
R L
R
Ld
R
L
R L
⊕
L
⊕
f
⋯ fd⊕
Ri L
R L
⊕
f
Trang 8•
•
R L
R L
R
Ld
R L
⊕
fd
R L
⊕
⊕
f
Trang 9n n
R L
R
L
R L
⊕
L
⊕
f
⊕
f
Trang 10f1 16 32 32
k
k1 k2 ⋯ k16
Trang 116
Trang 12Si 6
Trang 13i(x1 2 6 ( 2⨁x3 1⨁x4⨁x5 1⨁x6 2⨁x3⨁x6
i
x x x x x x
Trang 141 2 3
k k
1⨁m2⨁m3
Trang 15•
⋮