If private sector developers want to tinker with the building blocks of contact tracing app TraceTogether, or can come up with innovative ways to popularise it, they will be encouraged to do so.
In an interview with The Straits Times, Minister-in-charge of the Smart Nation Initiative Vivian Balakrishnan said: "If someone can come to us now and say, 'Hey, I can make it work on something which people are more likely to use', I will happily say, 'Please, take it, create something, submit it to us'."
If it meets the Government's security and privacy conditions, the invention can be part of the TraceTogether ecosystem, he added.
The building blocks of the app have been available for free since April. Publishing TraceTogether's source code helps other nations develop their own apps quickly without needing to start from scratch. Plus, developers can report any bugs in the app for fixing.
More importantly, the community can scrutinise the app, and citizens can find out for themselves if it can be used to spy on them.
"What you see is what you get. If we tell you we're not tracking your location, you can see we're not tracking your location," said Dr Balakrishnan, who is also Foreign Minister.
Contact tracing apps estimate the distance between users and the duration of their encounters based on the Bluetooth signal strength between nearby devices. It is a quicker way to identify the close contacts of Covid-19 patients than through interviews, for follow-up actions such as quarantine or isolation.
For such apps to be effective, at least three-quarters of the population need to be users. Singapore is still 2.2 million people shy of this benchmark, having garnered just two million TraceTogether users.
Even among those who have downloaded the app, Bluetooth tracing does not work well on iPhones.
A fix Apple introduced jointly with Google, released in the middle of last month, aims to improve the effectiveness of Bluetooth for contact tracing. But the fix limits the personal data that the health authorities can collect.
Singapore has decided against using the Apple-Google system, citing its ineffectiveness. Specifically, contact tracers using the Apple-Google system will not be able to map out the chain of infection, which is critical for epidemiological investigations and to identify clusters. What they will get is a pool of infected persons and a pool of close contacts, with no way of linking individuals.
Instead of working with Apple and Google, Singapore will be giving residents a small gadget dubbed the TraceTogether Token.
It says this will be more inclusive as people without a phone or a new smartphone can participate in digital contact tracing.
The first batch of 300,000 TraceTogether Tokens is being produced and will be issued later this month.
Asked if their use will be mandatory, Dr Balakrishnan said: "I'm very reluctant to go there.
"What I'm trying to get across is conversation, education, responsibility - a collective approach to securing our health and security."
Privacy advocates have argued against the collection of identity numbers such as NRIC or foreign identification card numbers, in addition to mobile phone numbers, by TraceTogether. Some have even argued for Singapore to use the Apple-Google system, said to be more privacy preserving.
Dr Balakrishnan said: "Frankly, they (tech giants) track far more than governments and they track for commercial reasons."
Singapore's preferred approach is open source - for both its contact tracing app and token - to make things better and safer, he said.
"I am very tempted to challenge them (Apple and Google) to open source it all... down to the source code of the operating system modules which relate to Bluetooth. I think that will be a good and positive move for the world."