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Gen generates Pk and Sk (l bits each), Enc encrypts m (length l) but by bit using each bit of Pk respectively, Dec decrypts ciphertext bit by bit using each bit of Sk respectively. How do I prove this scheme is not IND-CCA-2 secure?

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  • $\begingroup$ ... You find a CCA attack against the scheme, and show that the attack works. ​ ​ $\endgroup$ – user991 Dec 6 '15 at 8:30

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