How to verify the eight conditional probability values shown in the middle of page 50. That is, show that Pr[a|1] = 1, etc??

Example 2.3 Let P a, b) with Pr 1/4, Pr b 3/4. Let S1, K2, K3 with PrIKil 1/2 PrLK K3 1/4. Lete {1,2,3,4) Pr and suppose the encryption functions are defined to be eK, (a) 1, eK1 (b) 32: eK2 (a) 2, e 2 (b) 3: and eK,(a) 3, eKr, (b) 4. This cryptosystem can be represented by the following encryption matrix: Ki 1 2 K2 2 3 K3 3 4 Shannon's Theory 50 We now compute the probability distribution on e. We obtain the following Prill r12] 8 16 16 Pr 131 16 16 Now we can compute the conditional probability distributions on the plaintext, given that a certain ciphertext has been observed. We have: Pr a 2 Pr[b13]