|
|
|
|
|
|
|
USA NSA NATO KY-99 →
Narrowband analogue voice scrambler
- this page is a stub
KY-65 (KY-65E-1) is a tactical man-portable narrowband
frequency domain voice scrambler,
introduced in 1972
by the US National Security Agency (NSA)
for use in Vietnam.
It's an analogue system in which the audio spectrum (300-3000 Hz)
is divided into 9 bands of 300 Hz each, which are then swapped and (optionally)
mirrored, under control of the PARKHILL encryption algorithm.
|
The device is housed in a green metal enclosure that is similar to
that of the PRC-77 radio.
...
|
|
|
KY-65 was introduced in the early 1970s, when the Vietnam War was heating up.
Like all voice scramblers, it is inherently insecure and is therefore
vulnerable to exploitation. Although the NSA was aware of this — the device
was not approved for conversations above Confidential level —
it was deemded better than nothing [4]. It was also assumed that if the
Russians were to exploit it – assuming they were capable and interested–
they 'would have to devote inordinate resources' [4].
Despite their poor security, PARKHILL and compatible devices remained
in use for many years.
It is known that KY-75 was used in the AWACS environment and
for CROSSFOX tactical applications [5].
In 1981, it was even approved by SECAN (NATO) for tactical communication
at all classification levels [6]. At NATO it was regarded as a gap-fill
solution until a definitive secure narrowband voice unit
had been selected for NATO-wide use [6].
In 1989, all PARKHILL devices (KY-65 and KY-75) were replaced by the
KY-65A and KY-75A, which had an improved encryption scheme
and were approved for tactical communication at all classification levels.
These improved systems were is use until well after 2004.
The KY-65 was eventually succeeded from 1994 onward by the much smaller
and more versatile KY-99.
|
- KY-65 (E-1)
This is the inial version of the man-portable model of the device.
Its layout is similar to the PRC-25 and PRC-77 radios, allowing it to
be strapped to a man-portable radio harness.
It can be recognised by a hinged door at the front panel, that covers
the FILL connector. This version was approved for tactical communication at
Confidential level. It was replaced in 1989 by the KY-65A.
- KY-75 (E-1)
This is the airborne/shipborne version of the device.
It has different dimensions and a different layout of the front panel,
but is otherwise compatible with the KY-65.
- KY-65A
This is a later version of the man-portable KY-65, introduced in 1989,
in which an improved version of the Parkhill encryption algorithm is used.
It is approved for tactical communication at all levels of classification.
This version no longer has a cover over the FILL connector.
It is compatible with the KY-75A.
- KY-75A
This is a later version of the airborne/shipborne KY-75, introduced in 1989,
in which a modified version of the Parkhill encryption algorithm is used.
It is compatible with the KY-65A.
|
KY-65/75 divides the 300-3000 Hz audio spectrum into 9 segments
of 300 Hz each, as illustrated below. Each segment is 300 Hz wide and
can replace any other segment. In addition it may also be mirrored.
The total number of scrambling orders is therefore 18! · 29 =
185,794,560.
|
| |
Voice band divided into 9 segments of 300 Hz each
|
In the example below, the nine segments are shown in a scrambled order.
Furthermore, segements 5, 8 and 9 are inverted. The latter means that,
within this band, high tones are replaced by low tones and vice versa.
The scrambling order changes under control of the PARKHILL encryption algorithm.
This is a secret encryption scheme, developed by the NSA.
|
| |
Same signal but with scrambled frequency bands, some of which are mirrored
|
Below is a sample of a poor quality recording of KY-65 communication
of the US CPB/DEA. The file was retrieved via the WayBack Machine [7].
It is unknown when it was recorded. In the recording the synchronising AFSK
signal can be heard at the beginning of each conversation.
|
Device Narrowband voice security unit Purpose Man-portable tactical secure military voice communication Principle Frequency Domain Voice Scrambler Model KY-65E-1 Developer NSA Manufacturer ? Year 1972 Country USA NSN ? Successor KY-99 Classification Confidential Response 300 — 3000 Hz Bands 9 (300 kHz each) Algorithm PARKHILL Keys 185,794,560 Power 11 — 15 V/DC Dimensions (HWD) 122 × 287 × 409 mm (without battery pack) Weight 11 kg
|
Model KY-65 Year 1977 NSN 5810-01-050-2501
|
Model KY-65A Year 1989 NSN 5810-01-236-5245 Classification Top Secret
|
Purpose Airborne and shipborne tactical secure military voice communication Model KY-75E-1 Year 1972 NSN 5810-00-434-3641 Classification Confidential
|
Purpose Airborne and shipborne tactical secure military voice communication Model KY-75 Year 1977 NSN 5810-01-050-2502
|
Purpose Airborne and shipborne tactical secure military voice communication Model KY-75A Year 1989 NSN 5810-01-236-5246 Classification Top Secret
|
| • | 5810-00-434-3641 | TSEC/KY-75E-1 | Airborne/shipborne speech encryptor |
| • | 5810-01-050-2501 | TSEC/KY-65 | Man-portable speech encryptor |
| • | 5810-01-050-2502 | TSEC/KY-75 | Airborne/shipborne speech encryptor |
| • | 5810-01-051-3887 | TSEC/KY-65/75(A) | Circuit Card Assembly |
| • | 5895-01-056-4553 | AM-6747 | Speaker |
| • | 5810-01-062-2883 | - | Case assembly for KY-65 |
| • | 5810-01-062-2971 | TSEC/KY-65/75 | Cover for KY-65A |
| • | 5810-01-062-5391 | TSEC/KY-65/75 | Cover |
| • | 5810-01-236-5245 | TSEC-KY-65A | Man-portable speech encryptor |
| • | 5810-01-236-5246 | TSEC/KY-75A | Airborne/shipborne speech encryptor |
| • | 6135-01-036-3495 | BA-5390 | Battery, 15V Li |
| • | 6135-01-501-0833 | BA-5390 | Battery, 15V Li |
|
HYX-60 Telephone adapter and terminal HYX-65-1 Wire-line Adapter Local Unit AM-6747 Speaker (NSN 5895-01-056-4553) Z-AKE AC/DC Power Supply Unit for KY-65(A) Z-AKG Battery Pack Assembly for KY-65(A) CX-13211 Cable between KY-65 and AM-6879 Amplifier Converter BA-5390/U Battery, 15V Lithium (UB0023)
|
- PRC-25
- PRC-77
- PRC-104
- AN/GRC-21 5 (NSN 5895-01-156-0456)
|
- Brooke Clarke, TSEC/KY-65 Narrow-band Secure Voice Unit
2007. Accessed 20 May 2025.
- Jerry Proc and contributors, KY-65/75 Voice Security System (PARKHILL)
Accessed 20 May 2025.
- Jerry Proc and contributors, KY-75 Voice Security System (PARKHILL)
Accessed 20 May 2025.
- Thomas R. Johnson, American Cryptology during the Cold War, 1945-1989
Book II: Centralization Wins, 1960-1972.
NSA, Center for Cryptologic History, 1995. p. 380.
Partially released by NSA 2013-07-26 (EO #13526).
- A.C. Davies, Communications Security Equipment - TSEC/KY-65/75 (PARKHILL)
NATO, Memorandum ISWM-SYP-240-81. 28 August 1981.
- T. Huitfeldt, Communications Security Equipment - TSEC/KY-65/75 (PARKHILL)
NATO, Memorandum MCM-SYP-74-81. 11 November 1981.
- WUN Signals, Voice encryption systems, vocoders & voice compressors
WUN Signals-website. Accessed 21 May 2026 via WayBack Machine.
|
|
|
|
Any links shown in red are currently unavailable.
If you like the information on this website, why not make a donation?
© Crypto Museum. Created: Friday 20 May 2016. Last changed: Thursday, 21 May 2026 - 08:43 CET.
|
 |
|
|
|
|
