WHICH WHITE HOUSE CIRCUITS HAVE BEEN SECURED? As a follow on to the discussion of the White House use of DVP or some related digital security technique on secret service voice channels, does anybody happen to know whether they have also secured the telephone ("phone patch") circuits to Air Force 1 that have been traditionally left in the clear ? A list of those circuits in use recently follows. (Note that all of this information has been published in some form.) 1. "Nationwide" or "Echo-Foxtrot" half-duplex single channel nbfm voice via about 100 sites located on AT&T microwave relay towers throughout US tied by leased voice channels to manual switchboard at White House ("Crown Control"). Uses 415.700 mhz from AF-1, 407.85 mhz. to AF-1, at rather low EIRP's (less than a few watts). 2. "Combat Ciders" or "Autovon" or "Wideband" full-duplex FDM multi channel wbfm via nuclear hardened antenna's at many of the Autovon switching centers, also via relay aircraft and the various emergency command post aircraft (eg "Lookinglass"). Has provisions for secure voice and teletype (also fax) as well as fully automatic autovon voice trunks with standard autovon signalling and control. Trunks are located on 12, 16, 20 and 24 khz ssb channels, 0-4 khz is used for an order wire to ground station. Uses various frequencies in the 225-400 mhz military UHF band, 390.55 and 392.55 have been used as transmit from AF-1 in past. EIRP is (or was) very high, one published description of system said it was 1 Kw to counter absorption effects near nuclear fireballs. 3. "Yankee Zulu" full-duplex single channel nbfm voice via portable equipment set up by secret service at site of Presidential visit. This system has also been used for non-secure circuits to Presidential automobiles, and is probably what Reagan used to talk to the gunman in the golf coarse incident. Frequencies are around 163 and 172 Mhz at EIRP's of perhaps 25-100 watts. 4. "Mystic Star" hf ssb via about 10-15 AF bases throughout the world with remote transceivers controlled via telephone voice channels from Andrews AFB. This system is used for telephone traffic mostly when AF-1 is out of range of the UHF links, but at least two ssb voice frequencies (and a full duplex 75 baud secure teletype channel called "India Oscar" which use a special anti-multipath modem) are maintained continuously and used for coordination of other communications links. Frequencies are chosen from a list of about 150 scattered throughout the available chunks of hf spectrum and are designated by "fox" code numbers which change from time to time. 5. FLTSATCOM. A full-duplex nbfm voice channel to AF-1 is maintained via whichever of the Navy FLTSATCOM spacecraft are in an optimal position. This circuit (which isn't very private since 1/3 of the globe can pick it up) is mostly used for secure voice and fax transmission via conventional vf modems, but is occasionally used for clear voice traffic. ( AF-1 also uses other secure forms of satellite transmission as well). Frequencies for downlink are around 261 mhz and 291 mhz for the uplink. Uplink EIRP is several hundred watts. Are these circuits still in use ? Does anyone know of any other non-secure AF-1 telephone circuits that they feel at liberty to discuss. ? Finally has anyone thought that perhaps the White House decision to encrypt Presidential protection communications with DES (?) implies that we consider DES breakable by world class cryptologic establishments ? One suspects that we haven't left those communications in the clear by accident as the status and health of the President of great concern to both our allies and our principle adversary. Perhaps we are assuming that the various world equivalents of the NSA can monitor Presidential protection if they want to but terrorists and nosey journalists cannot ? Can anyone comment ?