NESTOR (encryption)

NESTOR was a family of compatible, tactical, wideband secure voice systems developed by the U.S. National Security Agency and widely deployed during the Vietnam War. NESTOR consists of three systems. The KY-8 was used in vehicular and afloat applications; the KY-28 was the airborne version: and the KY-38 was the portable or man-pack model. About 30,000 NESTOR equipments were produced prior to their replacement by the VINSON secure voice family.

Keying was accomplished by setting each switch in a matrix of switches to one of several positions. This was done using a separate mechanical key loader (KYK-28) that had a matching matrix of pins that could be set to different heights as instructed by a key list. The key loader was pushed into a matrix of holes, one hole for each switch. The loader also had two larger index pins that also cocked a spring that would return each switch to their initial position when the door covering the hole matrix was reopened, zeroizing the equipment.

NSA gave high priority to deploying NESTOR systems in Vietnam. Equipment was issued to field units in Vietnam beginning in 1965 with the KY-8 for stationary or vehicular use; the KY-8 was fully distributed by the third quarter of fiscal year 1968. The KY-28 was issued for use in aircraft beginning in 1967, as was the KY-38 for man-pack or mobile use. he KY-38 was fully distributed in 1968. T NESTOR was successfully used in some situation, but the overall experience was not good. NSA estimates that only about one in ten units were actually used. A variety of problems contributed to this rejection:

While many in the U.S. military believed that the Viet Cong and NVA would not be able to exploit insecure communications, interrogation of captured communication intelligence units showed they were able to understand the American's jargon and informal codes in realtime and were often able to warn their side of impending U.S. actions.

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