To guarantee security and privacy in data
transmission and archival applications, adequate efficient bulk encryption techniques are
necessary which are able to cope with the vast amounts of data involved. Experience has
shown that block-oriented symmetric product ciphers constitute an adequate design paradigm
for resolving this task, since they can offer a very high level of security as well as
very high encryption rates.
In this contribution we introduce a new product cipher which encrypts blocks of plain-text
by repeated intertwined application of substitution and permutation operations. While
almost all of the current product ciphers use fixed (predefined) permutation operations,
our approach involves parameterizable (keyed) permutations induced by BOOT decompositions
of Walsh matrices. By combining these highly unstable dynamics with an adaption of a very
fast shift register based pseudo-random number generator we obtain a new class of
computationally secure product ciphers which are firmly grounded on systems theoretic
concepts, offering many features that should make them superior to contemporary bulk
encryption systems.