Security for computer networks: an introduction to data security in teleprocessing and electronic funds transfer
Is the data encryption standard a group?
Proc. of a workshop on the theory and application of cryptographic techniques on Advances in cryptology---EUROCRYPT '85
On the security of multiple encryption
Communications of the ACM
A New Nonlinear Pseudorandom Number Generator
IEEE Transactions on Software Engineering
Proceedings of the 1982 conference on Cryptography
Proceedings of the 1982 conference on Cryptography
The average cycle size of the key stream in output feedback encipherment
Proceedings of the 1982 conference on Cryptography
Cycle structure of the DES with weak and semi-weak keys
Proceedings on Advances in cryptology---CRYPTO '86
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During summer 1985, we performed eight cycling experiments on the Data Encryption Standard (DES) to see if DES has certain algebraic weaknesses. Using special-purpose hardware, we applied the cycling ciosure test described in our Eurocrypt 85 paper to determine whether DES is a pure cipher. We also carried out a stronger version of this test, (A cipher is pure if, for any keys i,j,k, there exists some key l such that TiTj-1Tk = Tl, where Tw denotes encryption under key w.) In addition, we followed the orbit of a randomly chosen DES transformation for 236 steps, as well as the orbit of the composition of two of the "weak key" transformations. Except for the weak key experiment, our results are consistent with the hypothesis that DES acts like a set of randomly chosen permutations. In particular, our results show with overwhelming confidence that DES is not pure. The weak key experiment produced a short cycle of about 233 steps, the consequence of hitting a fixed point for each weak key.