From msuinfo!agate!ames!sgi!wdl1!nebula!koontzd Fri Aug 6 12:37:34 1993 Newsgroups: sci.crypt Path: msuinfo!agate!ames!sgi!wdl1!nebula!koontzd From: koontzd@nebula.lrmsc.loral.com (David Koontz ) Subject: Re: KY-28 Message-ID: <1993Aug3.024829.21493@wdl.loral.com> Sender: news@wdl.loral.com Organization: Loral Rolm Computer Systems References: <1993Aug2.195750.2076@schbbs.mot.com> Date: Tue, 3 Aug 1993 02:48:29 GMT Lines: 96 >The KY-28 was a "black box" used for air-air and air-to ground Comsec >during the Vietnam War. I doubt if they are still in use, and doubt if >you could get a schematic or system specification. > >During the Vietnam war, fighter pilots complained the KY-28 voice >encryptor took "too long to synchronize". It was "at least a nuisance and >at worst a hazard." As a result, the equipment was often switched off and >transmissions were made in the clear. The KY-28/TSEC was part of a family (KY-8 family) of secure voice equipment. Crypto (COMSEC) Custodians had lots of them in their vaults in various locations in the late '70s. They were used in Viet Nam, more commonly by the Navy. It was keyed through a small coverplate, that when opened exposed a number of holes. A key charging device was used that was comprised of slide stops on a series of rods and a cam mechanisim to force the rods out to the distance set by the slide stops against spring pressure. The rods would penetrate the holes and set permuter contacts according to the depth of penetration. A zeroize pin was activate by closing the cover, such that opening the cover again would zeroize the permuter settings, which would also render the equipment incapable of passing an alarm check and passing to operating mode. It took a lot of pressure to load a key set. This was all in a 1/4 ATR package in infamous NSA grey. The charging device was set according to a distributed and classified key list. The KY-28 was classified Confidential, or held the classification of the keys when loaded. The equipment was owned by individual services (who were stung by the 100 million plus price - procurement during the Viet Nam war included retrofitting aircraft inventory. This resulted in a slow down in procurement for AUTOSEVOCOM II, as the customers (services) didn't want to pay the cost and congress did not want another lemon. This eventually lead to STU-IIIs and would make a good 'Connections' episode. Some of this was covered in AVIATION AND AEROSPACE WEEKY before the advent of CCEP. There were several connectors below the charging port, for audio, digital, power and remote control. There was a green painted version in a different case for tactical land vehicle use. The voice encoding method was CVSD and ran at 20 some odd Kbaud (to match the bandwidth of a particular radio). I don't recall if I ever heard who manufactured KY-28s, old issues of AIR FORCE TIMEs would be a good place to check. AFT used to list contracts although crypto stuff fell off the public lists in the late 70s. Harris used to get the lions share for secure voice. The initialization delays were caused by two factors: crypto synchronization delays and digital transmission synchronization delays. The crypto sync delays could have been alleviated with cheaper digital storage (to MILSPEC) and/or by using other design principals for coming up with message indicators (initial vectors), the limiting factor being digital storage. During the era, fast training MODEMs were a bit of a rarity, covered I believe by a patent held by Bell Labs. Some of the delay might have been due to digital synchronization which could be overcome more readily today. The problem in its use was as alluded, you had to PTT and wait out synchronization tones. Slow synching equipment is better suited to full duplex installations not requiring frequent resync. The implemented message indicators were slow, long and relatively error immune. Trying to speed up the message indicator would call for error correction, which was rare and expensive during the era. Once synchronized an isosynchronous system using CVSD is not particularly susceptible to transmission errors, which causes only momemtary distortion as long as no clock event mistakes occur. Speeding up the message indicator would have required faster hardware and might have been technically unfeasible or prohibitively expensive. The KY-28 was/is handled through COMSEC distribution channels, in essence controlled by the NSA. If you have found access to one or more, the chances are they came from Viet Nam. Their introduction to service was predicated on the fact that the North Vietnamese were intercepting plaintext radio transmissions and exploiting the resulting gathered intelligence, as was done against the U.S./Allies by the Germans and Japanese in WWII. The KY-8 family has been replaced in U.S. inventories. The above reference to "black box" is from the fact that field level maintenance for the KY-28 was restricted to remove-and-replace. Troubleshooting the internals of one would consist of remove and replacing subassemblies with known good items according to a troubleshooting chart analysis of symptoms. All retired crypto gear is destroyed. The Navy used to dump emptied chassis (fixed plant crypto) off the Farallons, next to all that nuclear waste (heresay). I used to be an Electronic Communications and Cryptographic Equipment Systems Technician (30670) with SEIs for AUTOSEVOCOM and AUTODIN among others. I remember one of the old hands,an instructor in school describing a KY-1 (retired in the early 60's, replaced by the KY-3). I always thought there should have be a museum for this stuff. Some of the stuff used tubes and magnetic logic circuitry and should be preserved for its uniqueness. You want art deco, look at the color selection chart for KY-3s installed in quarters. KY-3s were built into safes. I had a change to buy an M-209 Hagelin mechanical cipher machine at the flea market in the early 80s, but didn't have the $450. I wouldn't know what a KY-28 would be worth to a collector (if there were a market). The government, if aware, would almost be sure to intercede. If you were to shoot lots of pictures first, they would have some value. One wonders about the availability of Soviet communications security equipment since the fall? Perhaps someone could recover gear from the Pueblo or Viet Nam? I also wonder about knock off copies as was done with the B-29 and space shuttle.