A user device containing sensors is delivered customized services without utilizing private user data or while only using it in highly constrained ways. This is accomplished by sending one or more queries to the user device. Each query requests a binary response and each query inquires whether or not the user device has obtained one or more specified parameter values, or range of parameter values, from one or more sensors incorporated in or in communication with the user device. For each query a binary response is received, which indicates that the user device has or has not obtained the one or more specified parameter values, or the range of parameter values, about which the respective query is inquiring.