2018 Volume E101.A Issue 12 Pages 2205-2209
Let X, Y be two correlated discrete random variables. We consider an estimation of X from encoded data ϕ(Y) of Y by some encoder function ϕ(Y). We derive an inequality describing a relation of the correct probability of estimation and the mutual information between X and ϕ(Y). This inequality may be useful for the secure analysis of crypto system when we use the success probability of estimating secret data as a security criterion. It also provides an intuitive meaning of the secrecy exponent in the strong secrecy criterion.