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Photograph: Unsplash/Kelvin Ang

TraceTogether: Things you might not know about Singapore's contact tracing app

What does TraceTogether even do? We answer all your questions


When countries around the world began ramping up efforts to slow the spread of community transmission, Singapore started rolling out TraceTogether, an app that uses Bluetooth to help with contact tracing. Contact tracing is an elaborate operation that involves activity mapping through systems like SafeEntry, analytic tools, surveillance footage, in-person door-to-door inquiries and TraceTogether is just a small part of it.

However, this unfamiliar technology has many wondering about data security and surveillance in Singapore and as a result, people are wary of downloading the app. Here's what you need to know.

What does the app do?

Before we get into this, we must first understand what happens when a case of Covid-19 is confirmed in the community. After a positive case is identified, the patient is interviewed and everything they've done in the past 14 days is listed down. People the patient has come in close contact with are also identified. Yup, every single one. 

To help with this process, SGUnited, GovTech and the Ministry of Health came up with TraceTogether as a way for Singaporeans to track close contacts should the need arise. Using Bluetooth, TraceTogether identifies a user's proximity to others with the app installed. It then tracks when you are in close proximity with these other people, including timestamps. If a case is confirmed, this information can then be used to identify close contacts based on proximity and the duration of an encounter between the two users.

Wait, so it tracks my movements?

Yes and no. While it does register users’ proximity to each other, it does not log a user’s movements on a map aka geolocation. This means that the app won't be able to see that you are currently in Jurong or Sengkang. The app uses received signal strength indicator (RSSI) values to measure the signal strength between phones. Calibrated RSSI values are used to estimate the approximate distance between users during an encounter. On top of this, all of this data is stored only on your phone, and not shared with MOH. Should MOH need the data for contact tracing, they will seek your consent to share it with them. 

Why does the government say we need this app?

While safe distancing, staying at home, and strict restrictions and measures have so far proved useful in reducing the spread, the app helps shorten the time taken for the arduous contact tracing process. Ultimately, TraceTogether complements contact tracing, but is not a substitute for professional judgment and human involvement in contact tracing.

Who oversees contact tracing anyway?

While contact tracing is ultimately under the responsibility of the Ministry of Health, the elaborate operation is also a multiplayer one and involves hospitals, the police, volunteers from statutory boards, Certis security officers, paramedics and the Government Technology Agency (GovTech).

How is my data protected?

First, geolocation data is not collected so the information retrieved will not be able to identify exactly where the user has been like Simpang Bedok or Geylang Serai Market. Second, the data collected is stored locally in the user’s phone in an encrypted form and will never be accessed unless the user has been in close contact with a Covid-19 case and is contacted by the contact tracing team. Third, mobile numbers are not revealed to other TraceTogether users. They are substituted by a random permanent ID. The mobile number and its corresponding user ID are stored in a secured server.

As an added layer of protection, TraceTogether creates temporary IDs that change regularly. Only these temporary IDs are exchanged between phones. Your mobile number remains secret and is not exchanged with other mobile phones. This is to protect users from malicious parties who may seek to eavesdrop and track interactions over time. Lastly, once contact tracing ceases, it will prompt users to disable TraceTogether's functionality. 

Who will have access to my data?

No one, unless you test positive. The data collected by the app is anonymised and encrypted, and does not reveal your identity or the other person's identity. When a user tests positive, their data can only be used by the MOH with their express permission. No other agencies, including the police, will have access to your data.

Is there any point in using the app if not everyone is on it?

TraceTogether enables community-driven contact tracing which means that it is more effective if more are on the app. Since its launch on March 20, only 25 percent of the population had downloaded the app – far below the 75 percent required for it to be fully effective. 

But many, including Prime Minister Lee Hsien Loong has acknowledged its shortcomings. He said that data privacy can be an issue to some who are concerned about sharing personal information but also added that we will have to weigh these against the benefits of being able to exit from the circuit breaker and stay open safely.

Do I have to use the app?

It's up to you, downloading the app is entirely voluntary. 

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