14 February 2013 Last updated at 19:36 ET

Taiwan Easycard: Risks and rewards of your life on one card

By Katia Moskvitch Technology reporter, BBC News

Jerry Huang and his family take the BBC around Taipei - with Easycard

Beep, and a smart card gets you on a bus.

Beep, and the same card opens your office door. Beep, and you buy your coffee at a corner shop. Beep, you pay for parking, open the exit gate. Beep, check out a library book.

Beep. Beep. Beep. At school or university, the card becomes your ID.

As Taiwan's capital, Taipei, wakes and the sunlight strikes its skyscrapers, the members of one family make sure their wallets contain one important thing - Easycard.

"We really can't go about without it, all our life depends on it," says Wenney Tsai, as she prepares breakfast for her husband, Jerry Huang, and children, Chelsea and Jonathan.

Taiwan introduced its smart card - equipped with radio frequency identification (RFID) tag - in 2002, following the examples of Hong Kong, Japan and Singapore.

The card was first used on buses and Taipei's Tube, the MRT.

Then it expanded to cover high-speed rail, which connects the capital with the south of the island, and some taxis. You can also use it at hospitals, shops, to rent a bicycle and even on domestic flights.

Today, Easycard is one of the world's most multifunctional smart cards. Other cities are now considering equipping their citizens with something similar.

So, what should they know about its benefits - and potential pitfalls?

Even hospitals in Taipei accept the card - but some people worry about security and privacy issues

Convenience and safety

"Good-bye, Chelsea." Ms Tsai drops off her 11-year-old daughter at a primary school in central Taipei.

The little girl quickly disappears, but moments later her mother's mobile phone beeps.

Students in many Taipei schools have ID cards integrated with Easycard

"Your daughter is safely at school," reads a text message sent to Mrs Tsai.

As soon as Chelsea touches her Easycard to a sensor at the entrance to the school, her mother receives a message.

Most schools in Taiwan's capital use the RFID technology, both to track students' attendance and to "reassure parents that their children are safe", says Chelsea's father.

"Chelsea can also buy something if she wants to - we put 200 New Taiwan dollars [($NT) (£4; $7)] on her card."

Hundreds of shops around Taiwan, and especially supermarket chains 7-Eleven and Family Mart, are equipped with the Easycard payment system.

The technology reduces the amount of cash in the till, which discourages robbers, according to Family Mart.

Security and privacy

So how does it feel - being able to control so many aspects of your life with just one card?

"It's convenient - this way we don't have such a fat wallet," says Mr Huang.

Jeans and other items in shops have active RFID chips - different from the passive ones inside Easycard

He even has his credit card integrated with the Easycard. Now, he says, he can go way above the usual spending limit of the smart card, fixed at $NT10,000 (£214; $336).

If he were to lose it, he would immediately call his bank - which in turn should notify Easycard.

Jason Chang, the chairman of the Easycard company, promises his firm is doing everything necessary to keep personal data safe.

The first generation of the card is the most popular - with nine million cards actively used every year - and it stores no personal information, says Mr Chang.

When the owner registers the card, his or her name is encrypted and stored in a centralised back-end system - not on the card itself.

Even if someone were able to hack the card, they would not get very far, says Mr Chang.

"The only information you can see on the card is how much money you have and the recent six transactions you've made," he says.

"The money on your card can be stolen, for example by using a dongle to make false transactions - but we can identify whether the card reader was issued by our company.

The Easycard was first used on buses in Taipei, but many more functions followed

"We only accept transactions from our card readers."

Once somebody hacked one of the cards and loaded it with more - fake - money. As soon as the card was used, the company spotted the fraud and alerted police.

The second-generation card, launched in 2012, has a chip similar to modern credit cards.

It protects all data with a long encryption key and is much harder to hack, says Mr Chang.

Security is more of an issue when the Easycard is also used as an ID card. Then it shows the owner's name and picture - and it could allow an intruder into your office.

"In that case, losing it would be just like losing your keys," says Jason Chen, from security company Sophos, in Taipei.

"You have to act swiftly and call Easycard to cancel it right away."

Tracking people?

But there are also privacy concerns, says Prof Shey-shi Lu, of National Taiwan University.

Right now, smart cards cannot be used to track your every move, he says.

The card is also used on certain taxis in Taipei

"There are two kinds of RFID chips - passive and active," he says.

For example, the chips used to protect your jeans against theft in a supermarket use active RFID - the chip can be detected and tracked from a certain distance.

"But smart cards need to make actual contact with the reader to get registered," adds Prof Lu. This means that it is only possible to know where you touched a sensor - at this 7-Eleven, then at that subway station, then at a library.

"But if they decide to switch [from passive] to active RFID chips, then it could get worrisome."

The Easycard is currently in talks with smart-cards providers in other Asian countries, including Octopus in Hong Kong, Ez-link in Singapore and T-Money in South Korea.

In a couple of years, says Mr Chang, you might need just one card to travel around Asia.

But Mrs Tsai and her husband are not convinced this would be a good idea.

"We like our Easycard because it's very convenient," says Mr Huang.

"But who knows what the other governments think - I'd feel uneasy to use one card everywhere."

And he adds with a chuckle: "And how would they manage the conversion rate - if I use my Easycard with Taiwanese dollars on it in Japan, the card will be empty in seconds."