Every day, millions of people use data generated by their bodies – their voices, faces, irises and fingerprints – to gain access to offices, secure government sites and financial services.

But biometric data has the power to produce even more sweeping changes: digital identities could soon be used to allow us to cross national borders without needing paper passports – documents that can be tampered with, forged, lost or simply taken away.

A face, palm moment

Although there are certainly problems with traditional paper passports, different concerns will accompany digital passports too. To start with, many feel a physical passport is a part of their travelling identity, and it gives some a sense of national pride that a body scan will not replace.

But of more importance are worries about the safety of the data storage systems behind biometric passports: how secure can they be, how much do you trust your government with your personal data – and how much control will you have over it?

Security experts argue biometric passports will allow authorities to spend less time probing legitimate travellers and devote more attention to catching criminals and undesirables.

Now a trial scheme to test advanced biometric passports that use facial, iris and fingerprint recognition has been announced by the Australian government.

Contactless travellers arrive

The aim is to eventually replace Australian passports with advanced biometric recognition that will provide an automatic, self-processing system for 90% of passengers.

The pilot is scheduled to begin at Canberra in July 2017, with bigger airports joining the scheme by November, and full implementation due by March 2019.

The government has awarded a AU$22.5 million ($18 million) contract to a company to build about 100 “world-leading automated and ‘contactless traveller’ clearance” machines for people arriving at Australia’s airports”.

The ambition is to do away completely with “smart gates” or manned booths where passport details are scanned or checked. Most people will simply walk down a corridor.

Peter Dutton, the immigration minister, said foreigners would also eventually be allowed to take part in the scheme.

The eyes didn’t have it…

But Australia is not the first country to test the feasibility of biometric passports.

Between 2004 and 2013, a programme called the Iris Recognition Immigration System ran at Amsterdam's Schiphol Airport and 10 UK airports that let frequent travellers pass border controls using iris identification alone.

This was dropped in favour of a scheme that records the data stored on microchips within passports, as the iris scans created false positives that meant travellers still had to join queues, and the system was expensive.

However, different varieties of biometrics are now used in many countries, including Canada and the United Arab Emirates, as the technology has improved.

But the biggest question that remains about the technology is how people will respond to having state agencies, such as police and immigration departments, possessing their most prized personal data.

A cyber state

Blockchain, the technology used to drive many cryptocurrencies, is thought to offer one possible solution to the privacy conundrum as experts says it is harder to hack into than other programs.

Estonia is leading the drive to become the first digital state, with all important archives and national data, as well as medical and educational records, now housed in a blockchain that verifies and encrypts each event that takes place within it. Citizens have e-identities they use to access benefits and pay taxes, for example.

The system was developed partly in response to fears of a cyber attack on the country’s digital assets and disrupt normal life, as happened in 2007.

It also seems to be true that, while there have been many successful raids on cryptocurrencies, most of them seem to have been caused by criminals gaining access to exchanges rather than disrupting blockchains.

Can blockchain hack it?

However, it is theoretically possible to hack a blockchain if digital pirates can gain control of more than 50% of its ‘hash rate’, the computing power that runs the system.

Some experts say this a flaw that could be exploited with the arrival of quantum computers, which can perform tasks far faster than conventional programs and could potentially decode blockchain encryptions.

If governments are to introduce biometric ID systems, state agencies will need to ensure their systems are secure and have the confidence of citizens. They also need to be able to explain who will be responsible, and how people will be protected, if things ever do go wrong.