[7935] in cryptography@c2.net mail archive
Type 1 cipher key lengths
daemon@ATHENA.MIT.EDU (Arnold G. Reinhold)
Fri Oct 6 13:03:10 2000
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Date: Fri, 6 Oct 2000 09:57:34 -0400
To: cryptography@c2.net
From: "Arnold G. Reinhold" <reinhold@world.std.com>
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Like most people interested in cryptography, I have always been
curious about the ciphers NSA uses to protect classified information
-- the so-called Type 1 ciphers. I have never found any reliable
information on these, outside of a few code names. Therefore I was
surprised to find the following paragraph on the Navy's Infosec page
which suggests that NSA uses 128-bit keys in newer systems and that
older equipment that is still in use employs keys that are shorter.
http://infosec.navy.mil/TEXT/PRODUCTS/CRYPTO/kg-40.html
>The KG-40A is a mandatory modified version of the older KG-40, which
>incorporates variable fill capability. The modification entails
>replacement of a printed circuit board (motherboard) and the front
>panel assembly. The KG-40A provides enhanced security using an
>improved cryptographic algorithm and electronic key capability.
>Because the KG-40A key is a standard 128-bit key, it can only be
>keyed by the AN/CYZ-10 Data Transfer Device (DTD) or a KOI-18 Common
>Fill Device (CFD). It cannot accept key from the KYK-13 Electronic
>Transfer Device (ETD) or from the KYX-15 Net Control Device (NCD).
>The KG-40A is an UNCLASSIFIED controlled cryptographic item (CCI)
>when unkeyed and is interoperable with the KG-40. When the KG-40A is
>keyed, classification equals that of the key installed.
