Dear Dr. Kelly,” the letter began, “although I am well aware of the patriotic contribution which you and your Company are already making in solving the many problems presented to you by the United States Government, I must make a personal request of you in a matter of the most urgent concern and importance to the security of the United States.” Typed on official Central Intelligence Agency letterhead and delivered to the head of Bell Labs, the message was deliberately vague:
In attempting to find a solution to an especially vital problem confronting us at this time, we urgently need the assistance of Dr. Claude E. Shannon of your Company who, we are informed on the best authority, is the most eminently qualified scientist in the particular field concerned. . . . If his services could be made available for this purpose on a basis satisfactory to both you and Dr. Shannon, I will be deeply grateful. I fully realize that even his temporary absence will be a great inconvenience to your organization and you may be sure that only the most compelling reason would cause me to make this request.
The writer of the letter was one of the most distinguished military men of his era: Walter Bedell Smith, the CIA director, former Army chief of staff to Dwight Eisenhower, and former ambassador to the Soviet Union. He was also the fourth person to lead the CIA, a job that, at that time, held little of the public profile it does now. Three days later, a copy of the same letter was sent from Kingman Douglass to Captain Joseph Wenger of the U.S. Navy, with a small attachment. “I hope very much this letter will succeed in its purpose.” Shannon’s past work offers some indication of what the CIA was after, but the fact that Douglass and Wenger were involved makes it even clearer.
Kingman Douglass was one of the sons of the upper crust whose life was a mix of prestigious private schools, paneled boardrooms, and pressurized war rooms. A graduate of the Hill School and Yale University, he flew planes in World War I and ran intelligence operations in World War II. He also served on two separate occasions with the CIA, including as assistant director for current intelligence.
Joseph Wenger also spent his career in the highest echelons of the intelligence world. “One of the first naval officers to realize the role of communications intelligence,” he was a U.S. Naval Academy graduate who would rise to become a rear admiral—and along the way would transform the way the Navy thought about and implemented cryptologic operations, becoming “one of the architects of centralized cryptology.” In the Pacific Theater of World War II, he found that the close study of Japan’s “message externals,” or seemingly trivial details ranging from call signs to communication habits, could be as cryptographically fruitful as the analysis of the messages themselves. By 1949, with two wars’ worth of experience and understanding, he was a leader in the Armed Forces Security Agency (AFSA), the forerunner to the modern NSA.
In a call with Shannon, Wenger made the case that the intelligence community needed his help. Wenger relayed the results to Douglass in a barely legible note: “I spoke to Shannon today on the phone and he appeared open to persuasion. He said he would reserve judgment until he could learn more of the problem and determine whether or not it is something he felt he could contribute. I offered to send an emissary to explain better to him as soon as his clearance is O.K.” John von Neumann also contacted Shannon that week, impressing upon him the significance of the request. It was very much in keeping with Shannon’s sensibility that he was neither overawed by being sought out for such a consultancy nor too quick to jump at the problem before knowing its full scope.
A week after the letter from CIA director Smith, Wenger and Douglas received a response from Bell Labs’ Mervin Kelly:
While there have been several other approaches to enlist Dr. Shannon’s services in connection with military activities and it has been our judgment that, in general, he could best contribute in his particular field by carrying on his researches independently, the matter with which your letter deals is of a more compelling nature and we shall, therefore, be glad to encourage and assist Dr. Shannon in participating to the extent of the preliminary examination you suggest.
This note sums up Shannon’s life in the early 1950s. Applications of information theory had mushroomed. The demands on his time had multiplied, and Shannon was doing his level best to keep the hordes at bay. When his resistance failed, it was almost always because of forces outside his control. Shannon made a principle of indifference; it was central to a career in which he chased his instincts, often at the expense of more prestigious or remunerative options. But his work on information theory had brought him national renown. And now, the federal government was asking for him by name.
The war’s end had brought the military a thorny problem: the exit from public service of many of the nation’s top scientists, mathematicians, and engineers. Beginning in wartime, as Sylvia Nasar wrote, “to be plucked from academe and initiated into the secret world of the military had become something of a rite of passage for the mathematical elite.” Now, though, “how to keep the best and brightest thinking about military problems was far from obvious. Men of the caliber of John von Neumann would hardly sign up for the civil service.” One solution, familiar to the men who occupied the upper rungs of the mathematical world, was the establishment of technical committees in close contact with various branches of the defense establishment. The committee that would become most familiar to Shannon—and the reason for the urgent messages from Wenger and von Neumann—was known as the Special Cryptologic Advisory Group, or SCAG.
In the NSA’s words, “the fundamental purpose in establishing SCAG was to assemble a specific group of outstanding technical consultants in the scientific fields of interest to the Agency, and thus provide a valuable source of advice and assistance in solving special problems in the cryptologic field.” Like most groups of this kind, SCAG was a means to a host of ends. There were knotty technical problems on which real, practical advice was sought. Committee members served as de facto headhunters, finding and sourcing talent at the request of senior government officials. There were frank exchanges about the nation’s readiness on a number of fronts. The first meeting of SCAG included sessions on the value and importance of communications intelligence, on a case study of a complex intelligence problem from World War II, on the state and purpose of the intelligence bureaucracy itself, and on an AFSA project code-named SWEATER. The committee’s concern ran the gamut from the technical to the philosophical.
From the time he was asked to serve in 1951 until the mid-1950s, Shannon made regular trips to Washington, D.C., for these meetings, serving on SCAG and its successor committee, the National Security Scientific Advisory Board. These meetings were multi-day affairs, and each day featured dawn-to-dusk sessions with the nation’s top brass discussing their most urgent intelligence dilemmas. “Because a considerable portion of each agenda had to be devoted to briefings by NSA officials before the Board could get to the consideration of Agency problems, it was of the utmost importance that the agenda contain the problems thought to be most pressing.” There was another practical reason that only the most pressing problems were brought to SCAG: these were men whose schedules were notoriously hard to align. In fact, a substantial measure of the record available to us about SCAG and other such committees concerns the challenge of herding about a dozen men of the highest scientific accomplishment into one room at the same time.
Boards of this kind were, by design, hamstrung. In the NSA historian’s own words, “Lacking accessible, secure areas, some of the advisors were handicapped by their inability to hold and consult cryptologic documents between meetings, and thus to live more or less with a problem. They could not benefit from the intuitive concepts that come with prolonged, even if intermittent, attention.” But the boards at least served the purpose of keeping the NSA leadership broadly connected with the scientific world.
The leadership with which Shannon was interacting had come of age in the midst of two massive intelligence failures. The horror of Pearl Harbor was seared in their memories. More recently, the invasion of South Korea by North Korea had again blindsided American policy makers, and by 1950, the country was again on a war footing. Which is all to say that Shannon was speaking with and working for men who had seen armed combat and were sending a new generation of Americans into another bloody conflict. The stakes were real; the intelligence requirements were manifold. Mathematical thinkers of Shannon’s and Von Neumann’s caliber were a necessary external measure of the defense establishment’s technological and scientific soundness.
It’s only from recently declassified documents that we get even this vague sense of Shannon’s work for the government during this time, and still many of the salient details remain classified. Shannon himself was cagey about what he did. Decades later, in an interview with Robert Price, he ducked the questions:
PRICE: And you were on the board of the NSA, weren’t you for a while?
SHANNON: I don’t think I was on the board. I might have been a member. I don’t think I was that . . . elevated a position.
PRICE: Well, you had dealings with the National Security Agency at some time I’ve been told.
SHANNON: Yes, that’s a better way to put it. . . . I got involved in cryptography at a later period. I was a consultant. I probably should . . . I don’t know . . .
PRICE: You’re talking about NSA now, probably the Advisory Board?
SHANNON: Well, I was invited . . . I think, I don’t know that I have any . . . even though this was a long time ago, I’d better not talk about. . . .
To some extent, this is classic Shannon: immune to self-puffery, unwilling to dive into topics that held limited interest. But Shannon tended to parry questions of this sort with a wry mix of sarcasm and humor. That he was nervous and halting in this exchange says a great deal about the secrecy surrounding the work he did.
Shannon had reason to be guarded: he had exposure to some of the nation’s most closely held secrets and systems and came into contact with the founding fathers and texts of the national security state. He understood both the gravity of the work and the need to keep the privileged information secret. This was no idle matter. One of Shannon’s fellow NSA scientific advisers, John von Neumann, was watched round-the-clock by uniformed military personnel when he was on his deathbed at the Army’s Walter Reed Hospital. Impressive though von Neumann’s mind may have been, it wasn’t immune from infiltration—or so the government feared. And what better time to infiltrate it—and grab the precious state secrets it held—than when it was in a medically induced haze?