Example: P = {a,b}, K = {k1, k2, k3}, C = {1,2,3,4}

1/4 3/4 Prob (plaintext)

a b

1/2 k1 1 2

1/4 k2 2 3

1/4 k3 3 4

Prob (key)

PrC (1)= 1/8, PrC (2)= 3/8 + 1/16 = 7/16, PrC (3)= 3/16+ 1/16 = 1/4

PrP (a|1)= 1 PrP (b|1)= 0

PrP (a|2)= 1/7 PrP (b|2)= 6/7

PrP (a|3)= 1/4 PrP (b|3)= 3/4

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