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JOHANN FRIEDRICH EULER (1741-1800): MATHEMATICIAN AND CRYPTOLOGIST AT THE COURT OF THE DUTCH STADHOLDER WILLIAM V*
ABSTRACT: During the latter part of the 18thcentury, some mathematicians started to turn their interest to cryptology. Their attitude differed in many ways from the approach of the professional cryptanalysts of their time, but their interest was far from being merely academical. Johann Friedrich Euler, mathematician and cryptologist at the Court of the Dutch Stadholder William V, showed a marked ability to put into practice some of the new principles and insights, forwarded in scholarly journals of the time.
KEYWORDS: The Netherlands, 18th century, cryptology, combinatorial analysis, J. F. Euler.
1 INTRODUCTION
The marriage between mathematics and cryptology may seem more or less natural to us today, or at least hard to avoid. This makes it easy to forget that we are dealing with what during the early years of the 20th century was still being conceived as basically a new development in an already existing and wellestablished field; a development too, by no means clear to last and still having to prove its value. Apparently, not even Friedman himself was entirely happy about this new alliance; he preferred to have physicists, chemists, biologists or people from the arts as collaborators, in short people with some sort of empirical training, not mathematicians who tended to focus on matters of theory rather than practice. In Military Cryptanalysis1, Friedman's famous training course in cryptology for the U. S. Army during the second world war, he firmly stated that:
The science of cryptanalysis is subordinated to the art of the cryptanalysis ( ...); mathematical approaches cannot always be expected to yield a solution in cryptology, because art can and must transcend the cold logic of scientific method ( ... ); the only effect [of mathematical training] being, frequently, to discourage one so much that one does nothing at all( ... ).
Clearly two souls were still living in Friedman: one looking to the past and one looking to the future as one is inclined to think. This obscures the fact, however, that mathematicians started to get interested in cryptology long before Friedman. In fact, these two souls of cryptology had been very much alive since the end of the...