Two movies in two days: this being Christmas, I took the day off, and — like many other residents of New York City, or so it seems from the packed-to-capacity theaters — decided to take in a movie. My wife, one of my sons, and I decided to see The Good Shepherd, with Matt Damon and Angelina Jolie, about the formation and early years of the CIA.

It’s a long movie, and I didn’t find Matt Damon’s character entirely credible; but there was enough suspense and complex plotting to make it an enjoyable afternoon. I won’t give away the plot; you can get bits and pieces of it in the Wikipedia summary and reviews that you’ll find here and here and here, as well as here and here. (Update: Rex Reed really didn’t like the movie: see his review here. Sadly, I have to agree with almost everything he says.)

But as a technology geek, there was one part of the movie that caught my attention, and that I’ve also seen mentioned in the context of government efforts to decode encrypted email messages and computer files. In The Good Shepherd, Matt Damon and his CIA colleagues are given a grainy, out-of-focus surveillance tape shortly after the disastrous failure of the Cuban Bay of Pigs invasion. It consists of an unknown man and woman in bed, with bits and fragments of a conversation that may or may not be significant. Throughout much of the movie, the action switches back to scenes of CIA analysts freeze-framing the film, blowing up individual frames and focusing on obscure bits and pieces of the bedroom scenery, background sounds, and other details that the human eye and ear filter out completely while trying to make sense of the conversation itself. To further complicate matters, it turns out that someone has doctored the film, adding in some extraneous background sounds and removing others; but eventually, as must always be the case in a Hollywood movie, the analysts piece together enough clues for Matt Damon to figure out where the action took place … and who was involved. The discovery sets up the major crisis in the film, where the main character (Damon) must confront good and evil, duty versus personal priorities, and make an awful choice.

Meanwhile, I kept thinking to myself while I watched this unfold: this all (supposedly) took place in 1961, when the technology of creating, editing, manipulating, and analyzing video movies was incredibly primitive by today’s standards. On the one hand, any amateur can create a high-def video clip with a readily available digital videocam, and then manipulate it into something almost arbitrarily different with readily available, low-cost editing tools. But on the other hand, the CIA presumably has its own razzle-dazzle technology, which is even more sophisticated.

But putting aside the technology details, the main thing that the CIA and NSA and FBI and DOD and a dozen other alphabet-soup government agencies have is resources: tons of people, tons of money, tons of computer power, and (in most cases) as much time as is needed to support painstakingly detailed, tedious work to dissect and analyze anything created by alphabet-soup agencies in other countries (e.g., the KGB during the Cold War era) or anything created by amateurs working alone or in small groups.

If I was up to some mischief, or if I simply wanted to transmit a confidential message that wouldn’t be deciphered by the FBI or the IRS, I might be willing to spend an hour or two creating a high-quality 2,048-bit encryption key, using freely available software like PGP. If I were a mischievous teenager, I might have enough time on my hands to spend a day or two, perhaps even a week or two, engaged in such an effort. And even though such an encryption effort might withstand a brute-force attack by even the mightiest supercomputer of the biggest government agency, there would be enough loose ends and vulnerabilities that I would have to assume that a determined effort would eventually thwart my efforts at secrecy. I would have to assume that a determined government agency would send a dozen agents, or perhaps a hundred, or maybe even a thousand, to turn my apartment inside out, analyze every bit of every one of the 100,000 files on my computer, interrogate everyone I’ve ever known, to somehow find the weak link in my security efforts. Indeed, if all else failed, they could simply pull out my fingernails or whatever passes for politically acceptable forms of physical “persuasion” in today’s political environment.

That doesn’t mean that passwords are cracked in five minutes, without breaking a sweat, by the computer hackers who work for the good guys, as you would be led to believe in TV shows like CSI Miami or 24. (or beautiful hackers like Kate Libby, the role that Angelina Jolie played in her first Hollywood movie, Hackers, in 1995) But it does mean that if you’re going to try hiding something from the government, you’d better hope that it’s small enough and unimportant enough that it never really gets on their radar screen. Otherwise, as Matt Damon and his colleagues demonstrated in The Good Shepherd, it’s just a matter of time.