From Sixteenth-Century Cryptography to the New Millennium — The Last 500 Years - Codes: The Guide to Secrecy from Ancient to Modern Times - page 62

to name those “best suited” for the assassination. Ultimately, Babington and
his cohorts were caught, and put to death by being, among other atrocities,
disemboweled alive. Mary went on trial and met the headman's axe (an axe in
no small part set in motion by a cryptanalyst) on February 6, 1587.
Antoine Rossignol
Now we turn to cryptographic developments in seventeenth century Europe.
France's first recognized full-time cryptologist was Antoine Rossignol who served
both Louis XIII and Louis XIV. In fact, on his deathbed, Louis XIII insisted to
his Queen that Rossignol be kept at court as a man necessary to the security of
the state. Rossignol also used his cryptanalytic skills to assist Cardinal Richelieu
(1585-1642). (Perhaps the quote that best epitomizes both the political bent
and character of Richelieuis: “If yougive me six lines written by the most
honest man, I will find something in them to hang him.”) Rossignol's initial rise
to prominence is due to the following anecdote. In 1626, the French intercepted a
cryptogram, carried by a messenger from the city of Realmont, which was being
held by the Huguenots. Rossignol cryptanalyzed it. The plaintext revealed
that the Huguenots were on the edge of collapse. Rossignol had the letter sent
back to the city together with the plaintext beside it. With their secret plight
revealed, the Huguenots surrendered without more fighting, again the result of
a cryptanalyst's skills.
Perhaps of greatest technical importance were Rossignol's improvements to
the nomenclators of the time (see page 40). These consisted of only one part,
meaning a single list of plaintext and code in alphabetical (or numerical) order.
In other words, they were listed in parallel, a system that was in place since
the start of the Renaissance. Rossignol determined that this parallel order
allowed for a means of cryptanalysis just by looking at what numbers stood for
which words. For instance, if he were able to find that 64 stood for launch and
98 stood for lethal , then no number between 64 and 98 could represent letter
since its code would have to be higher than 98 given the parallel matching of
code and plaintext. Also, if he wanted to find the code for legal , he knew it
had to be between 64 and 98, again because of the parallel matching. This
allowed a cryptanalyst too much advantage. He devised a method to thwart
such attempts. Rossignol insisted upon two lists, a tables a chiffer , consisting of
plaintext letters in alphabetical order, and code numbers in random order; and
the second part, used for decoding, called the tables `adechiffer , with plaintext
letters randomized and codes symbols in numerical order, the birth of two-
part nomenclators. (Think of these as similar to a bilingual dictionary.) The
revised and improved nomenclators were vital components of cryptology for
over four centuries. It is a testimony to Rossignol's cryptanalytic skills that
the word “rossignol” has entered the vocabulary of French slang to mean “a
tool that picks locks”. Rossignol also was a prime mover in the establishment
of the Cabinet Noir ,or Black Chamber — a headquarters for cryptanalysis
and intelligence gathering — which began France's firm grip on cryptography,
reading cryptograms of foreign countries throughout the seventeenth century.