IT expert testifies at Lai trial on Telegram's Secret Chat function

Chat records on instant messaging app Telegram will not be stored on the cloud drive if users turn on the Secret Chat function, the court heard on the eighth day of Jimmy Lai Chee-ying's trial.

The trial of the 76-year-old Next Digital founder - presided over by national security judges Esther Toh Lye-ping, Susana Maria D'Almada Remedios and Alex Lee Wan-tang without a jury - continued at the West Kowloon Magistrates' Court yesterday.

The prosecution originally planned to summon one of the accomplice witnesses - Next Digital's former chief executive Cheung Kim-hung - to testify in court yesterday, but the leading counsel of Lai's legal team Robert Pang Yiu-hung was absent since Monday and will not be available for two weeks.

The prosecution therefore decided to proceed with the written testimony of an IT expert Chow Kam-pui, an associate professor at the Department of Computer Science of the University of Hong Kong.

Chow said that he was requested by the police in March 2022 to provide advice on the instant messaging apps and social media platforms including WhatsApp, Telegram, Signal, Facebook, Twitter (now X) and YouTube.

Chow explained how the six apps and platforms work and conducted tests on how to use the platforms.

Test results showed Telegram users can delete or edit messages, and messages will not leave records on cloud servers if users activate the Secret Chat function. The platform also allows users to hide their phone numbers and customize their usernames.

WhatsApp users can edit or delete their sent messages, while group chat administrators can delete messages of members in the group chat.

Signal users can automatically delete sent messages after a certain period - from five seconds to one week.

And both Facebook and Twitter have functions including establishing pages, following other users, uploading photos and videos, reposting news feeds, sharing personal views, as well as a verified badge system known as "blue tick," Chow said.

The defense said they will apply to adjourn the trial for six to seven days if the prosecution decides to continue and summon Cheung to testify in court as before.

Lai's legal team will be led by barrister Steven Kwan Man-wai and King's Counsel Marc Corlett from New Zealand in Pang's absence.

Both the prosecution and defense agreed the 24 videos from Lai's online program "Live Chat with Jimmy Lai" will be played when witnesses are called. The defense said it is expected to take six days to play the 24 videos, totaling about 35 hours. The trial was adjourned to 11am today.

The prosecution will read out the written testimony from seven police officers - including senior inspector Hung Lai-fan whose testimony will focus on the financial investigation of the case.

Kwan told the court that the defense will argue the admissibility of the testimony of an expert witness Wang Guiguo, the Chair Professor of Chinese and Comparative Law at the City University of Hong Kong. Wang is the husband of pro-Beijing lawmaker Priscilla Leung Mei-fun.