A method comprising: in a first electronic device having: a host system, the host system including: a processor, and primary storage; and a communication subsystem in communication with the host system over a signal line, the communication subsystem including: a transceiver configured to communicate with a second electronic device over an extremely high frequency communication link (150; 522), exchange storage, and a communication subsystem microcontroller configured to control operation of the transceiver and the exchange storage; while the processor of the host system is off or in a low power mode: forming the EHF communication link between the communication subsystem and the second electronic device when the second electronic device is in close proximity to the first electronic device; receiving, at the communication subsystem of the first electronic device, a data file from the second electronic device via the EHF communication link; and storing the data file in the exchange storage of the communication subsystem, the data file in the exchange storage being firewalled from the primary storage of the host system such that the data file can be moved from the exchange storage to the primary storage only after the data file has been validated by the communication subsystem microcontroller; and when the processor of the host system is turned on or powered up and the communication subsystem microcontroller has validated the data file, transferring the data file from the exchange storage of the communication subsystem over the signal line between the communication subsystem and the host system to the primary storage of the host system. in a first electronic device having: a host system, the host system including: a processor, and primary storage; and a communication subsystem in communication with the host system over a signal line, the communication subsystem including: a transceiver configured to communicate with a second electronic device over an extremely high frequency communication link (150; 522), exchange storage, and a communication subsystem microcontroller configured to control operation of the transceiver and the exchange storage; a host system, the host system including: a processor, and primary storage; and a processor, and primary storage; and a communication subsystem in communication with the host system over a signal line, the communication subsystem including: a transceiver configured to communicate with a second electronic device over an extremely high frequency communication link (150; 522), exchange storage, and a communication subsystem microcontroller configured to control operation of the transceiver and the exchange storage; a transceiver configured to communicate with a second electronic device over an extremely high frequency communication link (150; 522), exchange storage, and a communication subsystem microcontroller configured to control operation of the transceiver and the exchange storage; while the processor of the host system is off or in a low power mode: forming the EHF communication link between the communication subsystem and the second electronic device when the second electronic device is in close proximity to the first electronic device; receiving, at the communication subsystem of the first electronic device, a data file from the second electronic device via the EHF communication link; and storing the data file in the exchange storage of the communication subsystem, the data file in the exchange storage being firewalled from the primary storage of the host system such that the data file can be moved from the exchange storage to the primary storage only after the data file has been validated by the communication subsystem microcontroller; and forming the EHF communication link between the communication subsystem and the second electronic device when the second electronic device is in close proximity to the first electronic device; receiving, at the communication subsystem of the first electronic device, a data file from the second electronic device via the EHF communication link; and storing the data file in the exchange storage of the communication subsystem, the data file in the exchange storage being firewalled from the primary storage of the host system such that the data file can be moved from the exchange storage to the primary storage only after the data file has been validated by the communication subsystem microcontroller; and when the processor of the host system is turned on or powered up and the communication subsystem microcontroller has validated the data file, transferring the data file from the exchange storage of the communication subsystem over the signal line between the communication subsystem and the host system to the primary storage of the host system.