Counterterrorism analysts have known for years that al Qaeda prepares for attacks with elaborate 'targeting packages' of photographs and notes.

Unsettling signs of al Qaeda's aims and skills in cyberspace have led some government experts to conclude that terrorists are at the threshold of using the Internet as a direct instrument of bloodshed.

Nearly all government advice on terrorism sacrifices practical particulars for an unalarming tone. The usual guidance is to maintain a three-day supply of food and water along with a radio, flashlight, batteries and first-aid kit.

For political and bureaucratic reasons, governments at all levels are telling far less to the public than to insiders about how to prepare for and behave in the initial chaos of a mass-casualty event.

The CIA now assesses that four nations - Iraq, North Korea, Russia and, to the surprise of some specialists, France - have undeclared samples of the smallpox virus.

The U.S. government has known since the early 1990s about Soviet-era smallpox weapons, and collected circumstantial evidence of programs elsewhere.

Smallpox, which spreads by respiration and kills roughly one in three of those infected, took hundreds of millions of lives during a recorded history dating to Pharaonic Egypt. The last case was in 1978, and the disease was declared eradicated on May 8, 1980.

During the morning rush hour on March 20, 1995, the Japanese cult Aum Shinrikyo placed packages on five subway trains converging on Tokyo's central station. When punctured, the packages spread vaporized Sarin through the subway cars and then into the stations as the trains pulled in.

The U.N. Security Council ordered Iraq in April 1991 to relinquish all capabilities to make biological, chemical and nuclear weapons as well as long-range missiles.

The United States, a signatory to the Chemical Weapons Convention, destroyed the last of its stocks of VX and other chemical agents on the Johnston Atoll, 825 miles southwest of Hawaii, in November 2000.

First developed as a weapon by the U.S. Army, VX is an oily, odorless and tasteless liquid that kills on contact with the skin or when inhaled in aerosol form. Like other nerve agents, it is treatable in the first minutes after exposure but otherwise leads swiftly to fatal convulsions and respiratory failure.

Given the volume of PC sales and the way McAfee runs its operation, I imagine there must be thousands of phantom subscribers - folks who signed up once upon a time and left the software behind two or three computers ago.

Dell fills its computers with crapware, collecting fees from McAfee and other vendors to pre-install 'trial' versions.

We know what's in our Cheerios and in our retirement accounts because the law requires disclosure.

Companies that receive government information demands have to obey the law, but they often have room for maneuver. They scarcely ever use it.

The Obama administration, like those before it, promotes a disturbingly narrow interpretation of the Fourth Amendment, misapplying the facts of old analog cases to a radically different digital world.

Federal prosecutors want to indict Julian Assange for making public a great many classified documents.

Activists and geeks, standing together, are demonstrating powers beyond the reach of government control.

It no longer counts as remarkable that Egyptians organized their uprising on social media.

A minimum precaution: keep your anti-malware protections up to date, and install security updates for all your software as soon as they arrive.

Friend of mine, a smart journalist, had his iPad stolen. He couldn't help that - the thief broke into his house. But his private, personal data wasn't stolen, exactly. Donated, more like. He had no passcode set on the iPad.

Privacy is relational. It depends on the audience. You don't want your employer to know you're job hunting. You don't spill all about your love life to your mom or your kids. You don't tell trade secrets to your rivals.

As Trotsky didn't exactly say, you may not be interested in electronic snoops, but snoops are interested in you, whether or not you keep Coke's secret recipe on your iPhone.

I learned the technology and tradecraft of electronic security in self defense, with a lot of expert help.