“Gentlemen do not read each other’s mail.” So Henry Stimson, Secretary of State under U.S. President Herbert Hoover is reported to have said. He closed the code-breaking office in the Department of State in 1929. However, by World War II, code-breaking was an acknowledged part of defeating the enemy, even if it meant reading private mail. Unprecedented changes to the way information is passed today mean that the boundary between public and private information blurs even more.

The American and French Revolutions took years to unfold. The revolutions known as the Arab Spring took days, spurred by Twitter and other social media.

Spies in past wars, like the Napoleonic military campaigns or the more recent Cold War, stole secrets and slipped them to the other side. Information about troop movements or knowledge of the atomic bomb passed to a well-defined enemy. Today’s hackers extract information through cyberspace. Malware is planted on another nation’s computers.

We hesitate, bewildered by what should be allowed and what shouldn’t. For good reasons, we don’t want our privacy invaded or spied upon, yet, we wish we had known more about the Boston Marathon bombers before they left their deadly pressure cookers.

Both the enemy and the new war zone in cyberspace remain shadowy and ill-defined. How do we define them? What are the new rules?