PARIS — A decade ago, on a visit to the U.S. Embassy here with a colleague for an interview, we were asked to leave our cellphones at the security gate. This was a new experience. We smiled, amused by this James Bond attitude. What kind of threat could these small, innocent phones — still dumb, not yet smart, at the time — possibly pose? They might, we were told, be used as listening devices.

Looking back, I wonder who might have been listening on whom. Following Edward J. Snowden’s leaks about wiretaps by the National Security Agency, the irony of this episode is obvious now.

Like our phones, we are smarter than we were 10 years ago. And thanks to Mr. Snowden, we now know what can be done with these small machines on which we have come to depend. Thanks to our constant use of electronic connections, our whole life is out there in the cloud, summed up in four letters: data.

Sometimes we feel that the cloud knows more about ourselves than we do. And we fear that the data sitting there are up for grabs, unprotected. If the N.S.A. has no effective limits on its reach, surely our conception of privacy must be rethought. President Obama, questioned about the scope of the Prism electronic surveillance program, initially told his fellow Americans (not quite accurately, it turned out): “With respect to the Internet and e-mails, this does not apply to U.S. citizens, and it does not apply to people living in the United States.”