Code-making and code-breaking

August 11, 2017

The hacking of the 2016 American election. The WannaCry ransomware attack on Britain’s National Health Service. The penetration of 500 million Yahoo accounts. The story of modern secrets is, in part, the story of the technology that protects them (or fails to). It’s the story of encryption, computer science, and cryptology, of the ever-increasing complexity of algorithms designed to shield information from prying eyes—and, seemingly inevitably, of their failure.

These technologies can seem unique to our time and place, modern threats created by modern tech. But they have decades-old origins. And, ironically enough, it was the quest to control the flow of wartime information in the twentieth century that gave rise to the enormous expansion of access to information represented by the modern Internet—and, in turn, to the secrecy-compromising developments that have recently dominated the headlines.

It was during World War II that many of the world’s leading minds in mathematics and early computing put their work to the side and signed up to help make and break codes. Wartime presented them with an urgent set of challenges: how to send secure messages across vast oceans, how to decode complex enemy correspondence, and how to do all of that as quickly as possible and with lives in the balance.

One tragic story illustrates the gravity of the work. On the morning of December 7, 1941, George Marshall, the Army’s chief of staff, had an important message for his Pacific Command: Japan had determined that it could no longer mediate its differences with the United States through politics. War was likely. But how best to transmit this information? Marshall could have used the trans-Pacific telephone—but this was an insecure system. So he used the slower, but more secure, commercial radio telegraph. The message arrived just after the attack on Pearl Harbor was over. The near destruction of the Pacific Fleet was, among much else, a wake-up call to America’s code writers.

Cryptology was a software and hardware problem. The “software” was language—how to deliver a message so that the recipient, and no one else, could make sense of it? In one famous example of “software,” American leaders recruited Navajo Indians to transmit coded messages because their native tongue was complex enough—and unfamiliar enough—to evade detection by the Axis powers. The hardware was some of the most advanced computing of its day—huge, room-sized machines that took ordinary messages and transfigured them into undecipherable sequences of numbers, symbols, spaces, and letters.

Why should this history of top-secret-keeping matter to us today? For one thing, it helps us recognize that our modern struggle of information security has some important historical antecedents. In appreciating that history, we can also come to better understand the early pioneers who did this work and saved lives in the process, names like Alan Turing and Claude Shannon.

Their stories provide powerful examples of academic mathematicians diving into practical, hard-headed work—work that inspired important contributions to technology and computer engineering. At the same time as they were drafted into cryptography on either side of the Atlantic, Alan Turing and Claude Shannon were writing long theoretical papers about communication, the foundations of thinking machines, and much else. Turing’s work on breaking Germany’s Enigma code helped lay the foundations of modern computing. Shannon, for his part, confessed that he didn’t particularly enjoy cryptography—but he did it, and conceded that it led to a great “flow of ideas back and forth,” between his wartime work and his seminal paper on information theory, which became the intellectual architecture behind the Internet.

The safeguarding of secrets, in other words, wasn't only a vital wartime imperative. In the process of thinking deeply about secrecy, Turing, Shannon, and other early computer scientists inaugurated the Information Age. Thanks to their work, the Internet offers us nearly the sum of human knowledge at the click of a mouse—as well as a not-entirely-secure home for our own secrets. Their legacies remind us that the race between code-making and code-breaking is never done—and that the pursuit of secrecy has long been one of the most powerful drivers of technological progress.

Goodman ’05 and Soni ’07 are the coauthors of two books: Rome’s Last Citizen and A Mind at Play: How Claude Shannon Invented the Information Age, published by Simon & Schuster in July.