Arnold Abrams, in Newsday (Sept. 19, 2004):

Once upon a time, roughly six decades ago, a teenage David Kahn, strolling the streets of his hometown, glanced into the window of Great Neck's public library and was attracted by a mysterious-looking book.

The title,"Secret and Urgent," was intriguing, but its cover - depicting a jumble of letters and numbers streaming out of the cosmos - captivated him.

Written by naval historian Fletcher Pratt, the book provided a broad history of codes and ciphers, focusing on the human secrets and battlefield strategies behind them.

"I found that stuff absolutely fascinating," said Kahn, who still lives in Great Neck, where the well-stocked library now holds five books - all dealing with codes - he has written."I didn't know it at the time, but it actually was interesting enough for a career."

With his career still blossoming at age 74, Kahn is widely considered a top historian of military intelligence. His books have shed light on the art and impact of secret communications, previously consigned to a dark, little-understood corner of world affairs.

Once largely limited to international diplomacy and military strategy, interest in cryptology has burgeoned dramatically in the past decade. It is a necessary part of electronic banking, e-mail, commercial transactions and Internet usage - all of which require high security.

Kahn's books - praised by reviewers as a mix of research, anecdotes, interviews and analysis - humanize the development of cryptology while describing the historic role played by codes and ciphers.

"He is the world's premier authority on code-breaking," Adm. Stansfield Turner, 80, director of the Central Intelligence Agency from 1977 to 1981, said recently of Kahn."His work is of tremendous help in understanding history - that of warfare and diplomacy, in particular - as well as the world we live in."

William Crowell echoed Turner. He is the former deputy director of the National Security Agency, which, as the largest component of Washington's intelligence community, monitors global communications.

"I learned a lot of my history from Kahn's writing," said Crowell, 63, whose 30 years of service in the secretive agency included a four-year stint as director of operations, overseeing the interception and deciphering of foreign communications and codes.

Crowell, now a board member of several companies involved with technological security, added:"David made the critically important subjects of cryptography and cryptanalysis understandable, interesting and even compelling. Before he came along, the best you could do was buy an explanatory book that usually was too technical and terribly dull."

Or as NSA historian David Hatch, 61, put it:"There is nobody comparable to Kahn. Many important figures have added to our scholarship, but nobody has written as widely, lectured as wisely and had his popular appeal."...