Apparatus for authorizing and de-authorizing a device such as a weapon is disclosed. The apparatus includes the electrical detection of a signal on the skin of the user, and optionally a radio signal from a central authorizing authority and the entering of a security code by the user. Upon receipt of the correct input, the weapon authorizes and is ready for use. If a loss of skin signal occurs, the weapon enters a safe state until reauthorized. Apparatus for generating the skin signal from both an ingestible and a skin-mounted apparatus are disclosed.