Patent attributes
A security system includes a physical sensor for determining presence of a first number of users within a detecting region, short-range readers for determining presence of a second number of authorized smart devices in response to ephemeral tokens, wherein the users may remain anonymous to the short-range readers, authentication servers for determining ephemeral tokens for smart devices in response to identifiers of the readers and the smart devices, a physical output device configured to provide a user detectable output, and a processor for determining whether the first number of users is different from the second number and for directing the physical output device to provide the user detectable output.