



NSA Type 2 cryptographic algorithm
Skipjack is an encryption algorithm for the transmission of information
(voice data in particular),
developed by the National Security Agency (NSA) in the USA.
It uses the DiffieHellman key exchange algorithm for the
distribution of the cryptographic session keys between peers.
The Skipjack algorithm was classified as
an NSA Type 2 encryption product.
It was intended for voice data networks (telephone) and was initially
developed for the NSA's illfated
Clipper Chip project
[1].
The algorithm was initially
classified as SECRET, so that it could not be examined in the usual manner by
the encryption research community.
After much debate, the Skipjack algorithm was finally declassified and
published by the NSA
on 24 June 1998 [2]. It used an 80bit key
and a symmetric cipher algorithm, similar to DES.
Data is encrypted in blocks of 64 bits, using an unbalanced Feistel network
with 32 rounds [3].
The algorithm was initially developed for use in secure
telephones, such as the AT&T TSD3600.
It was also used in the first Fortezza Crypto Card.
➤ Download a full description of the algorithm



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© Crypto Museum. Created: Wednesday 12 February 2014. Last changed: Sunday, 15 January 2017  12:58 CET.



