entirely biologically harmless operation After setting the object to protect to work and initially pairing the two wireless token devices with each other, the protected object refuses operation when exceeding the set distance between token and protected object. Advanced solutions offer communications on the basis of standardized communication protocols and based on standardized air interface links. Simple solutions make use of passive RFID tokens, thus requiring a higher transmission level from a reader attached to the protected object and illuminating the token for response. Chosen frequency band and allowed maximum transmission power level define the possible reach for the response from the token in the vicinity of the protected object. Applications Application is mainly known PC locking under for authenticated log-in conditions. Protected object controlling works with the token at hands working as a transceiver (RFID passive) or beacon transmitter (RFID active. Currently some similar applications are offered by several no-name vendors and under non-guaranteed specification. Standardization Relevant existing standard for such application is Bluetooth V4.0 Low Energy of 2009-12-17 with the profiles Find Me and Proximity. Security modes Published concepts for secure key transmission are published in several context. Standardisation in IETF (PKI), W3C (XML), ITU (X.509) is going on. Basically there are different concepts available for implementing a sound security concept: Active token sends fixed identity to be read by receiver (not robust against attacks) Transceiver sends initial code in challenge–response procedure and active token answers agreed code to prevent from fraudulent attacking Transceiver sends with varied power levels to stimulate various response levels from passive tag Transceiver and token communicate bi-directional for travel time (time of flight, TOF) estimates Beaconing token sends with varied power levels to support RSSI estimation with receiver Metrics options The metrics options for detecting separation of protected object and authenticated user have to take into account various physical phenomena and thus offer a variety of signal processing to overcome multipath propagation indirect and direct paths multipath fading excess reach of nearby colliding transmitters higher populations of transmitters The safe approach is travel time estimation with ultra-short pulses (e.g. UWB and CSS), the cheap approach is RSSI estimate with just variation of power levels. Standards based products available Many current product offers with reference to communication standards are just prototypes. Basic design is proposed e.g. with Texas Instruments sample offer using Bluetooth V4.0 low energy protocol standard and with comparable proposals of other