A source coding problem for sources with additional outputs to keep secret from the receiver or wiretappers

A new source coding problem is considered for a one-way communication system with correlated source outputs \{XY\} . One of the source outputs, i.e., \{X\} , must be transmitted to the receiver within a prescribed distortion tolerance as in ordinary source coding. On the other hand, the other source output, i.e., \{Y\} , has to be kept as secret as possible from the receiver or wiretappers. For this case the equivocation-distortion function \Gamma \ast(d) and the rate-distortion-equivocation function R\ast (d,e) are defined and evaluated. The former is the maximum achievable equivocation of \{Y\} under the distortion tolerance d for \{X\} , and the latter is the minimum rate necessary to attain both the equivocation tolerance e for \{Y\} and the distortion tolerance d for \{X\} . Some examples are included.