Other police tactics have been more subtle, and more challenging to address.
Hours after the media mogul Jimmy Lai was arrested, an employee at his company, Next Digital, received a message from someone posing as a part of tech support. Using the names of his employees, the message asked for login details to Mr. Lai’s Twitter account in order to set up a new iPhone for Mr. Lai.
Schooled from years of cyberattacks, the recipient of the message flagged it as suspicious. Mark Simon, an executive at Next Digital, said the company believed it was an attempt by the Hong Kong police to get the login information for Mr. Lai’s account. The tactic has added to a new level of paranoia that has made day-to-day operations more difficult, according to Mr. Simon.
“The problem is this slows everything down, because now everyone is double checking: ‘Did you send this message? Did you send that?’ It never stops; it just never, ever stops,” he said.
Calling new police tactics “more aggressive,” Mr. Simon said it had become difficult for Mr. Lai to hold on to a phone because of the spate of arrests.
“I think they have four of his phones now,” he said. “They take his phone every damn time. Teenage rock stars throwing fits don’t go through as many phones as Jimmy does, thanks to the Hong Kong police.”
Mr. Simon added that people in Hong Kong were quickly adapting to the new information security environment. With the police now able to tap phones without a warrant, many citizens have switched entirely to encrypted chat apps. Many, he said, go further, setting the apps to auto-delete messages and even eschewing taking paper notes in meetings.
“I just don’t want to come off this is the end of the world; it’s not. This is just a nuisance that we have to live with every day,” Mr. Simon said.
“In China this is normal stuff. In Hong Kong they’re learning how to operate.”
Edmund Lee contributed reporting. Lin Qiqing contributed research.