Annals of Cryptology
The Reader of Gentlemen's Mail: Herbert O. Yardley and the Birth
of American Codebreaking. David Kahn. xxii + 318 pp. Yale
University Press, 2004. $32.50.
On taking office as Herbert Hoover's secretary of state in 1929,
Henry L. Stimson discovered that the State Department included a
Cipher Bureau that had been reading cryptograms sent to foreign
ambassadors. Outraged, he cut off the bureau's funding and is said
to have declared that "Gentlemen do not read each other's
mail." One of those out of a job was bureau chief Herbert O.
Yardley. So it is apt that the recently published, badly needed
biography of Yardley is titled The Reader of Gentlemen's Mail.
Perhaps no one could have done so fine a job of writing this book as
code expert David Kahn. Kahn is, of course, the author of the epic
tome The Codebreakers, which since its publication in 1967 has been
the yardstick against which cryptologic history must be judged. His
writing is always carefully crafted and meticulously researched, and
this new book is no exception.
Yardley's role in the development of American codebreaking is an
interesting and vital story. Yardley, who was the source of much of
today's intelligence apparatus, was quite a character in the annals
of cryptology. He was many things to many people, but above all he
was a natural and inspired cryptanalyst in the days of
pencil-and-paper cipher and code systems. Kahn's account is the
first to show Yardley as a living, breathing person with all the
faults that come with humanness.
The book discusses at length Yardley's connections with William
Friedman, the U.S. Army's leading cryptanalyst. Many details of
their interaction are disclosed here for the first time.
Both Friedman and Yardley were eventually left behind when cipher
machines (such as the German Enigma, the British TYPEX, and the
American SIGABA) emerged after World War I, because the technology
needed to solve the ciphers created by the machines was far beyond
what either man could envision. Although Yardley was not much
interested in the solution of such ciphers, he did recommend their
use on occasion. Friedman, on the other hand, seems to have become
somewhat embittered about the entire subject, even though he himself
had developed some of the foundational tools used for the
cryptanalysis of machine ciphers. He became an administrator, and
Yardley turned to a bewildering variety of pursuits in order to earn
Yardley's sensational 1931 memoir, The American Black
Chamber, was an exposé of the cryptanalytic trials and
successes of American codebreaking as he knew it. The book, which
reads like a suspense novel, introduced the public to the arcane
subject of cryptanalysis and the sometimes nefarious means used to
do it. Kahn gives us many details about the book's publication and
its effects on the country, such as the debate that ensued about the
appropriateness of broadcasting what had been secret information.
This is all quite interesting reading, from which many lessons can
For all his likability, talent, charm and genius, Yardley can be
seen as a victim of himself. He never tried to play the game that is
required of those who want to be movers and shakers in government
circles. He probably could have done so successfully, but that kind
of endeavor would have seemed boring and pointless to him. Yet we
are fortunate that the world has Yardleys in it and authors like
David Kahn to tell us about them.—Cipher A. Deavours,
Mathematics and Computer Science, Kean University, Union, New Jersey