How to break Gifford's cipher (extended abstract)

Thomas R. Cain, Alan T. Sherman
1994 Proceedings of the 2nd ACM Conference on Computer and communications security - CCS '94  
We present. and implement a ,ciphertext-only algorithm to break Gifford's cipher, a stream cipher designed in 1984 by David Gifford of MIT and used to encrypt New York Times and Associated Press wire reports. Applying linear algebra over finite fields, we exploit a time-space tradeoff to separately determine key segments derived from a decomposition of the feedback function. This work, the first proposed attack on Gifford's cipher, illustrates a powerful attack on stream ciphers and shows that
more » ... ifford's cipher is ill-suited for encrypting broadcast data in the MIT-based Boston Community In-, formation System (BCIS).
doi:10.1145/191177.191227 dblp:conf/ccs/CainS94 fatcat:lcpp32olazdjnl4av62jxxvo2i