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Cryptography: Theory and Practice
by Douglas Stinson CRC Press, CRC Press LLC ISBN: 0849385210 Pub Date: 03/17/95 |
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The probability distributions on and
are as follows:
What are the optimal impersonation and substitution strategies?
of C. Prove that C is indeed an OA(n1 n2, k, λ1 λ2).
Compare the entropy bounds for Pd0 and Pd1 with the actual values you computed in Exercise 10.1.
HINT To compute , use Bayes formula
We already know how to calculate . To compute
, write m = (s, a) and then observe that
if ek(s) = a, and
otherwise.
To compute , use Bayes formula
can be calculated as follows: write m1 = (s1, a1) and m2 = (s2, a2). Then
(Note the similarity with the computation of p(m).) To compute , observe that
and ek(s2) = a2, and
, otherwise.
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