Build a cipher that is secure against message recovery attack but not semantically secure

Build a cipher that is secure against message recovery attack but not semantically secure

I know the definitions of both of the securities against message recovery and semantic, but I dont know how to actually build a cipher that meets these conditions, I mean, I dont know how to define let mathcalE E,D where Ek,m ;... and you can see that it is secury against MR because of ..., but is not semantically secure because of ... yet. I would like to know, at least, how to start building such cipher. Message recovery attack: Let mathcalE E,D be a cipher. The challenger chooses a random m from message space mathcalM, a random k from key space mathcalK, computes a random c xleftarrowtextR Em,k and sends c to the attacker. The attacker, then, sends hatm back to the challenger. The attacker wins the game if hatm m. Let p be the probability Prhatm m. The advantage of this attacker is Bigvert ; p - frac1Vert mathcalM Vert ; Bigvert The cipher is secure against MR attack if this advantage is negligible for all efficient attackers.

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