primitive Cold War secure voice communication

“The big news in COMSEC in the 1960s, however, was secure voice. US government users would use the telephone for classified talk, and the only solution was to provide them with a secure handset. Secure voice requirements spanned a broad swath from high-level point-to-point conversations to tactical military applications in the jungles of Southeast Asia. Well aware of the vulnerabilities of voice, NSA approached secure voice cautiously, and for many years secure voice capabilities lagged behind record traffic.

For strategic systems, NSA developed two devices in the 1960s. The KY-9 was a narrow-band digital system using a vocoder, and it was the first speech system to use transistors. The advantage of the KY-9 was that it could be used on a standard Bell System 3 kHz-per-channel telephone system withou modification. The disadvantage were many, however. It was big and heavy, encased in a safe that had to be unlocked every morning before the system could be activated. It was also expensive (over $40,000 per copy) and a true “Donald Duck” system which required the users to speak slowly to be understood. Only about 260 sets were deployed, all to high-level users, mostly Air Force.

Built by Bell Labs under contract, (the KY-3) was housed in a safe. It was big, klunky (sic), and looked a lot like the KY-9, but without many of the drawbacks. The KY-3 was a broadband digital systems, so voice quality was better, and it was not a push-to-talk system. But what brought it inot wide use was its employment in the Autosevocom network.

Autosecvocom was a secure voice network designed by NSA. Local networks consisted of KY-3, whose individual voice conversations were first decrypted, then reduced to narrow-band signals and digitized in the HY-2 vocoder, and finnally re-encrypted for transmission using a KG-13. The autosecvocom system achieved wide acceptance and some 2,700 KY-3s were sold to users worldwide, including the White House, the Joint Chiefs of Staff, and the Strategic Air Command”

grabbed from Thomas R. Johnson’s recently declassified history “American Cryptology during the Cold War, 1945-1989” at The National Security Archive.

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