In representative embodiments, a geo-fence cryptographic key material comprising a geo-fence description defining a geographic area and associated cryptographic key material is assigned to an entity for use in authenticated communications. The validity of the cryptographic material changes state based on whether the entity is inside or outside the geographic area. This is accomplished in a representative embodiment by suspending the validity of the cryptographic key material when the entity is outside the geographic area and reinstating the validity of the cryptographic key material when the entity is inside the geographic area. A geographic update service determines the validity of the cryptographic material in part using location updates sent by the entity. Entities that are not geo-aware can delegate the location update to a geo-aware device. Encryption can be used to preserve privacy.