A Hong Kong health-care firm concerned about confidential medical reports going missing turned to a Singapore firm for a solution.

The Gastrointestinal Endoscopy Centre, which entrepreneur Michael Tse started two years ago, conducts hundreds of endoscopy tests a month and couriers the results to doctors but some documents were getting lost en route.

The risk to patient privacy meant the firm needed to find a better way and a conversation between Mr Tse and his good friend, Professor Lam Kwok-Yan, set things rolling.

Prof Lam, a Singaporean who is an expert in information security, and Mr Tse founded the start-up Soda about two years ago, with an initial funding of about $1 million, including their own funds as well as from angel investors.

It went about developing software that could solve the problem and came up with Soda - or Safe Of Data App - which encrypts information like contact lists and documents found on computers, smartphones and tablets.

Mr Tse, who chairs Soda, told The Straits Times on a visit to Singapore yesterday: "We built a safe for data."

As long as the data is in the Soda folder, it is encrypted. Opening the file in the Soda software automatically de-crypts it. When Soda-encrypted documents are attached in e-mail, they remain secure because of the encryption.

Prof Lam said: "Encryption is easy to do. The challenge is to make it easy for users to use."

Many security companies encrypt data when it is being sent, he added, "but we encrypt data on the computer and phone; if the devices are hacked, the hackers will not be able to see the encrypted data".

Initially Soda software was available on computers only but now comes in the form of an app for iPhones and Android-based phones.

The Gastrointestinal Endoscopy Centre successfully piloted the software.

The basic app is free and allows users to encrypt their data on the mobile devices. If they pay US$499 (S$628) a year, they will be able to send Soda-encrypted files for example as e-mail attachments to other people.

Next year, Soda aims to expand more into South-east Asia before heading to other regions, said Mr Tse, a former investment banker who retired in 2008 to pursue his own business interests.

"We think there will be about 500,000 Soda downloads next year and we can sign up between 50 and 100 corporate customers," he added.

Corporate customers will pay a subscription based on the number of users.

Financial institutions are potential customers, said Prof Lam. Banks, for example, may want to send statements to their customers but are afraid of data being stolen by hackers. "So if banks provide the Soda app for their customers, then they can send Soda-encrypted account statements to them without fear of hackers stealing personal information."

The start-up has 12 employees, including eight technical staff based in its Science Park office here. It has marketing employees in Malaysia and Hong Kong.