Advertisers have said openly that they will not stop tracking just because a consumer sends a Do Not Track signal through his or her browser. Facebook has said it needs more clarity on whether a Do Not Track signal applies, for instance, to social plug-ins like the Facebook "like" button, which is integrated into millions of web sites.
Still, companies are refining the controls users have over their data, on mobile devices as well as on desktop computers.
In addition to requiring applications to seek user permission before tracking location, Apple has included in its latest mobile operating system a way for users to disable or reset a series of digits that identify a particular device for tracking purposes. The Advertising Identifier, as it is called, replaces what was an immutable unique device identifier and allows app developers to monitor user behaviour, but it also gives consumers the option of turning it off.
In 2011, Google sought to distinguish its social networking tool, Google+, as privacy-sensitive. It introduced the idea of "circles" as a way to limit sharing certain things with certain people.
To be sure, market rivalry does not mean that companies are not worried about regulatory scrutiny of their use of personal data.
Facebook agreed to 20 years of audits by the Federal Trade Commission after the agency found that the company had deceived consumers by making public data that they had intended to be private. In a measure of change, Facebook began nudging its users to review their privacy settings before they could start using the new search tool the company introduced this year.
"What does privacy mean?" Facebook's chief privacy officer, Erin Egan, asked at the RSA Conference. "It's understanding what happens to your data and having the ability to control it."
That very imperative seems to be buoying a cottage industry of privacy start-ups. A Boston-based company, Abine, is testing what is effectively the opposite of a Facebook single sign-in for the web.
Instead of exposing your Facebook login credentials to dozens of web sites, the company offers a proxy email address or phone number for every transaction. You sign in with the email address and a password you remember; Abine creates one address for an ecommerce site you visit, another for a news site, another for a dating site.
Abine offers the basic service for free and plans to charge a monthly fee for more advanced features.
Another company, Wave Systems, showed off its new consumer privacy tool on the RSA exhibition floor last week. Named Scrambls, it encrypts a social network post or email, effectively locking it, and lets the author choose who should have a key to read it. The company plans to market Scrambls to parents, among others, as "a seat belt" to protect their children on social media. For now, it is free.
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