If you have a U.S. passport, get ready to upgrade it to the digital variety.

After three years of research and discussion, the State Department has finalized most of the technical and logistical details of new, supposedly tamper-proof passports embedded with a "smart-card" chip.

If current plans hold, they'll become standard issue for U.S. travelers as soon as February.

Proponents say the chip, which will contain the holder's personal data and digital photo, should allow you speedier entry as you pass through customs in the United States or other countries.

Because the chip's data can't be altered, proponents say, forging passports will be virtually impossible. That, they say, gives authorities a potent new anti-terrorism weapon.

When swiped across an electronic reader, the chip in the passport wirelessly transmits data to a customs officer's computer screen. The e-passport relies on radio frequency identification technology.

The new passport looks much like the traditional type. But the smart-card chip, embedded in the back page, makes it slightly thicker. If the chip is broken or malfunctions, the holder can continue to use the passport as a nonelectronic passport, or buy a new one.

Once the new version is available, it will take up to a year for all new passports to be issued in the new format. Americans with valid traditional passports won't have to replace them until they expire. The new passport will cost $97.

The Sept. 11 terrorist attacks prompted calls for improved border security. The new e-passport is perhaps the most visible aspect of the government's foray into digital technology for border control.

The e-passport has raised concerns among critics who say it lacks adequate privacy safeguards. Wireless transmission of data compromises security, and important personal data could fall into the wrong hands, they say. With proper equipment, someone could remotely intercept personal data, they say.

Wireless transmission could lead to what's called "skimming" or "eavesdropping," says Cedric Laurant of the Electronic Privacy Information Center, a Washington, D.C.-based advocacy group. In skimming, an intruder secretly uses a device to read the chip's data from as far away as several feet.

Americans walking with their passports could be essentially broadcasting their nationality and other personal information, Laurant says.

Those concerns are outdated, said Frank Moss, State Department assistant secretary for passport services. A metallic anti-skimming material has been added to the passport's cover and spine. It limits retrieval of the data to within an inch of the passport, Moss says.

The State Department is also considering adding a layer of protection by encrypting the information so it can be read only by authorized devices, Moss says.