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NSA
Whiz Wheel · 1987
- wanted item
HAL-001 Vigenère Wheel, nicknamed Whiz Wheel or Wizzie Wheel,
was a manual cipher disc, invented around 1987 by Jeffrey E. Man, a
cryptanalyst at the US National Security Agency (NSA).
It was developed to supplement the paper-based Vigenere table
supplied with the Diana One-Time Pad cipher system used by
US Special Forces (SF) — a.k.a. Special Operations Force (SOF).
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The device consists of two metal discs on a common axle. Each discs has
the 26 letters of the Latin alphabet at its rim.
The bottom disc is in (clockwise) alphabetical order (A-Z),
whilst the top disc is in reverse order (Z-A).
A third alphabet – also in reverse order – is printed on the bottom disc,
hidden by the top disc, and is visible through a window cut into the top
disc.
The wheel is used to find the third unique letter of a three-letter combination,
or trigraph.
One letter is from the message or plaintext; one letter is the key as printed
on the one-time pad; and the third letter is the cipher that is ultimately
transmitted to the recipient.
The process is reversed at the receiving end of the message:
P + K = C
C + K = P
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In the above equasions, P is the plaintext, C is the cipher text
and K is the key. The 3-letter trigraphs are derived from a
Vigenère Square where two letters
are derived from row and column, with the third letter beging determined by the
intersection of the two letters.
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The Diana One-Time Pads came with a copy of the Vigenère Table, but also a
list of all of the unique trigraphs formed. The Communications Sergeant
(called the 'COMMO") was expected to memorise all of the trigraphs so that they
could encrypt/decrypt in their head.
What made the Whiz Wheel invaluable in the
field was the speed at which it could be used (as opposed to relying on the
Viginère Table), when conditions, such as exhaustion, 1 made it difficult
to recall the required trigraph [5].
The image on the right shows Jeff Man in 2023, when the Whiz Wheel was
on display at the National Cryptologic Museum (NCM) in Fort Meade.
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In 2023, at the annual conference of the Special Forces Association,
a former COMMO confirmed to inventor Jeff Man, that when they were
deployed, they would often go without sleep for 48 to 72 hours,
which obliterated their ability to recall the memorised trigraphs [5].
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In the series Special Forces Stories on YouTube,
this one hour interview with Jeff Man – the inventor of the Whiz Wheel –
was published in 2021.
Source
Lionfish Cyber Security
Date
30 January 2021
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Device Manual cipher disc Purpose Alternative to the Vigenère Table supplied with the Diana OTP Principle Modified Vigenère Table Model HAL-001 Vigenère Wheel Name Whiz Wheel Inventor Jeffrey (Jeff) E. Man (NSA Cryptanalyst) Manufacturer NSA Year 1987-1990 Country USA Material Aluminium Dimensions 76 mm (3") Weight 17 g (0.6 oz) Quantity 15,000 ~ Price USD 10
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- HAL-001
- Whiz Wheel
- Diana cipher disc 1
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The name 'Diana Cipher Disc' was never used by NSA or by any of its users,
but was introduced by Creative Crafthouse who makes wooden replicas of
the device.
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- Ralph Simpson, HAL-001 cipher disc
ICCH newsgroup, 1 May 2026.
- Jeff Man, Whiz Wheel
MrJeffMan on Twitter (X), 23 March 2021.
- Jeff Man, More Tales from the Crypt...Analyst
Presentation by Jeff Man at NolaCon 2019.
Adrian Crenshaw on YouTube, 19 May 2019.
- The Chief, HAL-001 or the "Whiz Wheel"
The Black Chamber (website), 2 February 2024.
- Jeffrey Man, Personal correspondence
Crypto Museum, June 2026.
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© Crypto Museum. Created: Saturday 02 May 2026. Last changed: Sunday, 04 October 2026 - 14:53 CET.
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![HAL-001 Vigenère Disc (Whiz Wheel) [5]](img/whiz_wheel_clean_thumb.jpg "image # whiz_wheel_clean.jpg")
![Whiz Wheel prototype (left) and production wheel (right) [5]](img/whiz_proto_thumb.jpg "image # whiz_proto_large.jpg")
![Whiz Wheel inventor Jeff Man at the NCM in 2024 [5]](img/whiz_jm_thumb.jpg "image # whiz_jm.jpg"){kind=small}
![Man re-invents wheel [5]](img/man_reinvents_wheel_thumb.jpg "image # man_reinvents_wheel.jpg"){kind=small}
![Whiz Wheel on top of the original Viginère Table [5]](img/whiz_table_thumb.jpg "image # whiz_table_large.jpg")
![Whiz Wheel prototype (left) and production wheel (right) [5]](img/whiz_proto_large.jpg)
![Man re-invents wheel [5]](img/man_reinvents_wheel.jpg)
![Whiz Wheel on top of the original Viginère Table [5]](img/whiz_table_large.jpg)
