(FORTUNE Magazine) – "Who Can You Trust?" asks a special report on CNBC, and most other business media have raised the same question. Trust is the topic of the moment, thanks to Enron, Andersen, Global Crossing, Tyco, Adelphia, and others (not to mention some priests and politicians, but we're not going there). It's a bigger topic than we tend to realize. Today's crisis of trust is more than just an unhappy coincidence of several management and accounting failures. It's a new fact of life.

The reason is that in an economy based on digitized information, many sources of value have escaped our human ability to control or even understand. We ultimately trust the evidence of our senses, but our senses aren't much use when most of what we must buy, sell, or evaluate never assumes physical form. In a world like that, we have to trust the company or person we're dealing with. That's why trust is becoming the most important asset in the digital economy.

Consider how digitization is transforming three key aspects of business:

SECURITY AND PRIVACY Remember the last time you received a delivery from UPS? The guy in the brown uniform handed you a brown electronic keypad with a small screen; you took a brown stylus and signed your name, inklessly, on the screen. Did you stop to think about what you had just done? You had given UPS your signature in digital form, making it reproducible without limit; it is stored, somewhere, right now.

So is much else. Think of what your credit card company knows about you; even more soberingly, what your mortgage issuer or health insurer knows. Vast troves of personal data are available digitally, meaning that with a few mouse clicks they can be sent anywhere in an instant--honestly, dishonestly, even accidentally.

There was a time when your signature emanated only from your pen, and your personal data could be found only on paper. Now they're just digits, totally beyond your control. If you can't trust the companies that control them, you're in trouble--and so are those companies.

FINANCIAL STATEMENTS Why are so many firms being forced to restate earnings, and why aren't their accountants catching the problems before they happen? For all of business history until quite recently, most corporate assets were tangible, and those are the assets that accounting was designed to handle. We still had plenty of business fraud, but in the end someone could go to the rail yard and see if the goods were there. In many of today's high-profile disasters, by contrast, the assets at the heart of the trouble are purely digital, and digits are a lot easier to hide than boxcars.

Enron's baffling partnerships were entirely intangible, and only the efficiency of today's infotech enabled the company to create hundreds of them. How could Andersen approve them? Well, can you explain to an accountant's satisfaction what was wrong with them? These things would give Stephen Hawking a headache, which is why demands for greater disclosure, while useful, will get us only so far. If Enron or any other company wants to defraud investors through incomprehensible, derivative-based, off-balance-sheet, offshore financial boogie-woogie, it will find a way. In a digital economy, it can always find a way. Investors must decide whom they trust, and if they get burned, there may be no chapter two, as Enron showed.

MEDIA Not many years ago, anyone trying to doctor a piece of audiotape, a movie film, or a photograph could be caught. Experts could tell where the tape had been spliced or the film image altered. Not today. Sound and image, stored digitally, can be changed easily, cheaply, and undetectably. Any well-equipped video studio could produce a clip of President Bush saying absolutely anything, and no TV viewer on the planet could tell if it was fake.

When U.S. forces discovered a videotape of Osama bin Laden, its acceptance or rejection around the world was a referendum on trust in the U.S. because no one could independently determine the tape's authenticity.

In the new, digital, trust-based economy, the stakes are extraordinarily high. A company's trustworthiness, embodied in brand and reputation, is increasingly all that customers, employees, and investors have to rely on. That's why Alan Greenspan said recently that a company's value today may amount to its "capitalized reputation." Experience shows that this asset is built slowly and painfully but can be lost in an eye blink, and in losing it, you may lose everything.

All around us we hear the question, Who can you trust? The more important question is, Who trusts you?