Shhhh! It’s an NSA Museum, but Spy Agency Is Unclear on Concept : Washington: National Security Agency opened it in July but told no one. It’s hard to find, and its phone number may not exist.

In the shadowy world of U.S. intelligence agencies, the National Security Agency has always been the most clandestine.

About 20,000 people work at the mirror-windowed complex at Ft. Meade between Baltimore and Washington, but until 1989 there wasn’t even a sign in front of the buildings. The 1952 executive order that created the agency was itself classified. For years it was a federal crime even to say it existed.

Therefore, as might be expected, when the NSA opened its own museum recently, it did things a little differently. It held the first opening in July and didn’t tell the public. It held a second ribbon-cutting in December for the public but didn’t tell the press.

When a reporter heard of the museum recently from a source close to the NSA, he was able to locate it only after an extended series of calls to the agency.

“People tend to be a bit sensitive around here,” said Stephen J. McAnallen, a surprisingly good-natured man finally located under the oxymoronic title of NSA public affairs officer. “It sort of comes with the territory.”

With McAnallen’s help, the National Cryptologic Museum was ultimately discovered in a defunct motel at the end of a crumbling road behind a Shell gas station just off Route 32 from the Baltimore-Washington Parkway. It would be a highly anonymous location were it not surrounded by a high chain-link fence with barbed wire on top.

The museum is the latest step in the gradual demythologizing of the agency--a process former director and until recently Defense Secretary-designate Bobby Ray Inman started more than 10 years ago, said David A. Hatch, 51, an NSA historian waiting inside.

“Some fairly detailed books and articles” about the long-secret agency had appeared by then and, although many in the agency remain almost pathological in their passion for anonymity, “people have discovered the world won’t crumble if the words “cryptology’ or “sigint’ appear in print,” he said.

Sigint--intelligence gleaned from the interception and decryption of government and military signals--is, of course, what NSA is all about. And, as exhibits in what once was the motel’s bar indicate, its origins are as old as coded writings and invisible ink.

The museum displays two books on cryptography dating from the 16th Century, as well as a small but elegant wooden cipher machine, found in West Virginia and dating from around 1800, that may have originated in the fertile mind of Thomas Jefferson.

Other exhibits show how sigint multiplied during the Civil War, when Union and Confederate signal corpsmen read each other’s wigwagged troop-movement signals and tapped each other’s telegraph lines.

But the bulk of the museum is devoted to sigint’s boom years--those between World War I and 1974, when publication of F. W. Winterbotham’s book “The Ultra Secret” finally disclosed the greatest and most closely held secret of World War II.

An improbable combination of Polish foresight, British genius, American technology and German hubris permitted the Allied forces to read German and Japanese radio signals for most of the war. It was so vital that most historians now recognize it as the key ingredient in the Allied victory, particularly at such crucial moments as the Battle of the Atlantic against German U-boats; the Battle of Midway, which halted Japan’s advance in the Pacific; and the invasion of Normandy.

At the heart of the code-breaking struggle was the storied Enigma cipher machine, an ingenious electromechanical typewriter fitted with a system of adjustable rotors designed to produce a cipher so complex it would defy human solution.

The Germans considered their Enigma-based codes unbreakable. And so they might have been had not some Polish cryptographers managed to reproduce an Enigma machine from documents sold to them by an embittered German aristocrat whose fortunes had reduced him to a signal clerk.

After the invasion of Poland, the replica Enigma was smuggled to Britain, where British code-breakers managed to devise a pioneering electronic computer called “the bombe,” designed to exhaust and therefore solve the mathematical possibilities of Enigma rotor settings. The rest is, quite literally, history.

Museum curator Earl J. Coates, 54, appears mildly miffed that NSA’s own bombe was loaned to the Smithsonian Institution’s “Information Age” exhibit before his own museum was up and running. The NSA museum, however, is awash in Enigma machines--Luftwaffe Enigmas, U-boat Enigmas and even an Enigma visitors can play with themselves.

Also on display is the U.S. Sigma machine, the only cipher machine of World War II whose codes were never broken.

The National Cryptologic Museum, reached by exiting the Baltimore-Washington Parkway at Route 32 and heading behind the Shell station, is open from 9 a.m. to 3 p.m. Monday through Friday. Some at NSA say you can reach it at 301-688-5849. Others at NSA deny that number exists.