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← USA NSA Data KG-40AR →
Half-duplex Link 11 data encryptor
- wanted item
KG-40 was a half-duplex cryptographic device
that provided data protection for the US Navy's
Link 11 system and other systems that met the Tactical
Data Information Link A (TADIL-A) data standards. It was developed in the US
in the mid-1970s and was used by the
US Department of Defence (DoD)
and by NATO.
In 1991, the KG-40 was succeeded by the improved KG-40A.
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The original KG-40 supported only 128-bit keys
for which nearly every common
DS-102 and DS-101
compatible FILL device,
such as the popular KYK-13,
could be used. In 1991, the KG-40 was followed by
the KG-40A, which provided better cryptographic
security by the implementation of an
improved cryptographic algorithm.
At the same time, the existing KG-40 units were modified by installing
the KG-40 MOD upgrade, involving the replacement of the motherboard and
the front panel assembly. The new KG-40A units were manufactured by SPAWAR
(US Navy).
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After the upgrade, the KG-40A supported a variable key length that was
larger than the initial 128-bits. As a result, the
KYK-13 key transfer
device and and the KYX-15
Net Control Device (NCD) could no longer be
used 1 and the KOI-18
or CYZ-10 devices had to be used instead.
When unkeyed, the KG-40 and KG-40A are an UNCLASSIFIED
Controlled Cryptographic Items (CCI).
The KG-40A is approved by NATO SECAN for classified information up to the level
of COSMIC TOP SECRET [2].
At present we have no better image of the KG-40 or the KG-40A.
In 2006, the US Navy started looking for a replacement for the ageing
KG-40A units and started a procurement procedure. Eventually in 2012,
the order was given to Ultra Electronics
in the UK, resulting
in the development and delivery of the
KG-40A Replenishment (KG-40AR)
[1].
This is the first time in history that the US DoD has procured a
Type 1 cryptographic device from an offshore company.
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It is sometimes erroneously suggested, even on renowned website
such as [4]
and [5],
that the KG-40A introduced a key length of 128 bits
and that after this, the KYK-13 fill device could no longer be used.
Everyone seems to quote from the same source [4] however.
This can not be correct, as the KYK-13 does support a
maximum key length of 128 bits.
This means that the original KG-40 probably
used a 128-bit key, whilst the later KG-40A required a longer key.
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If you have additional information or pictures of the KG-40 or the KG-40A,
please contact us.
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© Crypto Museum. Created: Sunday 01 March 2015. Last changed: Sunday, 25 February 2018 - 15:12 CET.
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