How do you explain to people that they are a YouTube sensation, when they have never heard of YouTube or the Internet? That's a question we faced during our January visit to North Korea, when we attempted to engage with the Pyongyang traffic police. You may have seen videos on the Web of the capital city's "traffic cops," whose ballerina-like street rituals, featured in government propaganda videos, have made them famous online. The men and women themselves, however—like most North Koreans—have never seen a Web page, used a desktop computer, or held a tablet or smartphone. They have never even heard of Google (or Bing, for that matter).

Even the idea of the Internet has not yet permeated the public's consciousness in North Korea. When foreigners visit, the government stages Internet browsing sessions by having "students" look at pre-downloaded and preapproved content, spending hours (as they did when we were there) scrolling up and down their screens in totalitarian unison. We ended up trying to describe the Internet to North Koreans we met in terms of its values: free expression, freedom of assembly, critical thinking, meritocracy. These are uncomfortable ideas in a society where the "Respected Leader" is supposedly the source of all information and where the penalty for defying him is the persecution of you and your family for three generations.

North Korea is at the beginning of a cat-and-mouse game that's playing out all around the world between repressive regimes and their people. In most of the world, the spread of connectivity has transformed people's expectations of their governments. North Korea is one of the last holdouts. Until only a few years ago, the price for being caught there with an unauthorized cellphone was the death penalty. Cellphones are now more common in North Korea since the government decided to allow one million citizens to have them; and in parts of the country near the border, the Internet is sometimes within reach as citizens can sometimes catch a signal from China. None of this will transform the country overnight, but one thing is certain: Though it is possible to curb and monitor technology, once it is available, even the most repressive regimes are unable to put it back in the box.

What does this mean for governments and would-be revolutionaries? While technology has great potential to bring about change, there is a dark side to the digital revolution that is too often ignored. There is a turbulent transition ahead for autocratic regimes as more of their citizens come online, but technology doesn't just help the good guys pushing for democratic reform—it can also provide powerful new tools for dictators to suppress dissent.

Fifty-seven percent of the world's population still lives under some sort of autocratic regime. In the span of a decade, the world's autocracies will go from having a minority of their citizens online to a majority. From Tehran to Beijing, autocrats are building the technology and training the personnel to suppress democratic dissent, often with the help of Western companies.