CIS 5371 Cryptography
QUIZ 4 (5 minutes only)
This quiz concerns Private Key Encryption.
1. Describe the four steps of the eavesdropping indistinguishability experiment PrivK eav
A , Π
, for an encryption scheme Π = ( Gen , Enc , Dec ) with adversary A .
1 The adversary A is given 1 n and outputs a pair of messages m
0
, m
1 of length . . . . . . .
2 A key . . . . . . . . . is generated running . . . . . . . . . ; a random bit is selected: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ; the ciphertext . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . is computed and given to A .
3 The adversary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 The output of the experiment is . . . . . . if . . . . . . . . . . . . and . . . . . . otherwise.
The adversary succeeds if P rivK eav
( A , Π) = . . . . . . .
2. Define Semantic Security I
A private-key encryption scheme Π = ( Gen , Enc , Dec ) has indistinguishable encryptions in the presence of an eavesdropper if for all . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Mike Burmester
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