cryptography Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...

, the S-1 block cipher was a

block cipher In cryptography, a block cipher is a deterministic algorithm that operates on fixed-length groups of bits, called ''blocks''. Block ciphers are the elementary building blocks of many cryptographic protocols. They are ubiquitous in the storage a ...

posted in

source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...

form on

Usenet Usenet (), a portmanteau of User's Network, is a worldwide distributed discussion system available on computers. It was developed from the general-purpose UUCP, Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Elli ...

on 11 August 1995. Although incorrect security markings immediately indicated a

hoax A hoax (plural: hoaxes) is a widely publicised falsehood created to deceive its audience with false and often astonishing information, with the either malicious or humorous intent of causing shock and interest in as many people as possible. S ...

, there were several features of the code which suggested it might be leaked source code for the Skipjack cipher, which was still

classified Classified may refer to: General *Classified information, material that a government body deems to be sensitive *Classified advertising or "classifieds" Music *Classified (rapper) (born 1977), Canadian rapper * The Classified, a 1980s American ro ...

at the time. However once David Wagner had discovered a severe

design flaw ''Design Flaw'' is the fifth studio album by Art Bergmann, released on the Other People's Music record label in 1998."Bergmann back to form". ''The Province'', November 6, 1998. The album featured acoustic recordings of songs, primarily from Ber ...

, involving the

key schedule In cryptography, the so-called product ciphers are a certain kind of cipher, where the (de-)ciphering of data is typically done as an iteration of '' rounds''. The setup for each round is generally the same, except for round-specific fixed va ...

but not the underlying round function, it was generally accepted as being a hoax—but one with an astonishing amount of work behind it.

Bruce Schneier Bruce Schneier (; born January 15, 1963) is an American cryptographer, computer security professional, privacy specialist, and writer. Schneier is an Adjunct Lecturer in Public Policy at the Harvard Kennedy School and a Fellow at the Berkman ...

noted that S-1 contained a feature never seen before in the open literature; a G-table that results in key and data dependent rotation of S-boxes to use in a given round.The S-1 Algorithm
Sep 6, 1995, When Skipjack was eventually declassified in 1998, it was indeed found to be totally unlike S-1.

References

See also