Digital tools to help curb online eavesdropping

Let's be clear. Your personal information online is not always yours to control.

Thieves could grab a Social Security number stored unencrypted in a doctor's computer; the National Security Agency could order an e-mail provider to unlock correspondence; even the phone company could supply the police with a map of your whereabouts for the past several months.

For now, short of living in a cave without a cellphone, there are no fail-proof technological tricks to avoid this exposure. There are, however, a variety of tools to minimize your digital footprint:

Experts say never to use the same password on multiple sites. Reality says that following that advice is nearly impossible.

But keeping strong and safe passwords, which means keeping multiple passwords, is crucial to protecting accounts. A relatively safe bet is to use a password manager. They generate random passwords and store them in an encrypted safe, to which only you have the key (usually in the form of a master password).

Password managers include Dashlane, LastPass and RoboForm. Some work better than others on mobile devices. Apple's new operating system, iOS 7, includes a Password Generator that promises to produce "a unique, hard-to-guess password" and "remember it for you."

Two-step authentication is another safeguard. Many large Web companies, including Google and Yahoo, along with recently breached services like LinkedIn, now offer this option. If you turn on two-step authentication, entering a user name and password sends a code to your phone by voice mail or text message. The service then requires that you enter the sent code. It takes extra time to set up and use the system, but far less than it would take to clean up a thief's mess.

Tracker blocking tools let you see the companies tracking your activities on the Web and block them if you wish. Some popular blocking tools include Ghostery, Disconnect and Abine. To the dismay of advertisers, some browser makers now offer consumers a way to block third-party cookies, tiny pieces of code that track where you go on the Web.

A virtual private network, or VPN, can help blur your tracks. It creates an encrypted tunnel between your computer and the VPN's server, obscuring your Web browsing to others, including your Internet service provider. But some VPNs log your Internet traffic, compiling a rich history of your Web travels. HTTPS Everywhere, a browser extension, takes you to secure, encrypted versions of websites wherever possible, protecting you from eavesdroppers, for instance, when you are using public Wi-Fi.

If you don't want Google or Bing (the two main search engines) to compile your search history data, there is the upstart search engine called DuckDuckGo. The company makes money by serving advertisements based on the keywords searched in real time, then discards the search history.

An e-mail is like a postcard: It can be easy for others to read. And an e-mail provider's promise of encryption provides little comfort.

That's because when a message is sent from a Gmail user to a Yahoo user, for example, it travels on the wide open highway of the Internet, which makes it vulnerable to theft. Moxie Marlinspike, a security researcher, uses the analogy of a lock and key. "Let's say the door to my house is locked, but I keep the key Scotch-taped next to it," he said. Anyone who can grab the key can get in.

Even the most advanced privacy tools might not work, though, if the basics are ignored.

The most basic safeguard of all — the equivalent of hand-washing in digital hygiene — is to keep software updated. A host of known security bugs often are fixed with each release, so ignoring those sometimes annoying calls to update are done at your peril.