Instead, the 40-somethings with successful careers and families to protect use code-words — "shopping," ''dreaming" — to disguise their intentions. Like 99.9% of other demonstrators, they also wear masks, too flimsy to ward off tear gas but covering enough of their faces to complicate any effort to identify them, when out rallying on the streets.

"You don't use the word 'protest' in our conversations," Chan said. "I believe one day they will just eliminate whoever participated."

As paranoid as that sounds, the lengths to which Hong Kong protesters go to conceal their identities are a consequence of living in the shadow of Big Brother. Across the border that separates Hong Kong from the rest of China, never-sleeping high-tech surveillance is ubiquitous, with facial recognition, forests of cameras, and other privacy-penetrating automated policing tools massively deployed to help keep the Communist Party in power and enable its powerful state security apparatus to track what citizens are doing, saying, reading, buying and planning, and to weed out dissent.

Becoming a tightly controlled city like all the others in China, its special freedoms extinguished, is the future that protesters say they are fighting to avoid for Hong Kong. For her many critics, Hong Kong Chief Executive Carrie Lam pushed the freewheeling international hub for trade, business, ideas and innovation one step closer to that dark scenario with her decision Friday to criminalize the wearing of masks, invoking rarely used emergency powers to expedite the ban and bypass the legislature.

In doing so, the embattled leader who previously adopted a conciliatory approach before traveling to Beijing this week to celebrate the Communist Party's 70 years in power enflamed critics' widespread fears about their future. For many, banning face coverings, even surgical masks and face paint, proved the argument they've been loudly, and increasingly violently, making with hundreds of protests since June that Hong Kong's freedoms are being chipped away bit by bit.

Lam said the mask ban and the use of emergency powers that allow her to "make any regulations whatsoever" were necessary to curb violence and deter "radical behavior." She noted that other countries also prohibit face coverings. France voted a ban in 2010, targeting Muslim women's full-face veils. Canada since 2013 has made the wearing of identity-concealing masks at unlawful gatherings punishable by 10 years in jail.

But in Hong Kong, protesters say the shadow cast by China over the territory makes their situation unique. Hong Kong's government says none of its departments use facial recognition technology in conjunction with the tens of thousands of CCTV cameras it has installed to help with policing, crowd control and other jobs across the territory.

But trust in Lam's government is now mostly non-existent among those wearing masks. The same goes for China's commitment to let the territory largely be its own boss, under a "one country, two systems" formula.

"I think there's no border between Hong Kong and China when they want to access data," said a 48-year-old accountant who would only give his first name, Kelvin. He spoke Thursday night as reports — which proved well-founded — swirled around the city about the imminent imposition of the mask ban. "I don't doubt that there's data interchange every day."

For the many in Hong Kong who visit family and do business in the mainland, there are also concerns of being swept up by the opaque legal system there if identified as having joined the protests.

Edwin Cheng, who works in banking, said he turned down a business trip to Tianjin, in China's northeast, next week because he's fearful he may have been flagged for having protested and because security agents might check "my phone full of the news and foul language."

He said a friend who works in insurance was picked up on a business trip to Shanghai and held for two weeks by Chinese authorities who identified him as a protester.

Staying on the sidelines of a small, peaceful sit-down rally where a couple of hundred people chanted slogans for an hour before dispersing, an office worker in polished shoes and neatly ironed pants said the only reason he wasn't demonstrating with the others was because he hadn't brought a mask.

For the sake of "my job and my career, my security," he would only give a first name, Matthew. The 25-year-old said his boss has made clear he could be fired for protesting. A friend on his soccer team who, like Matthew, worked at a government-funded organization, lost that job after police arrested him at a protest, held him for two days and then released him without charge.

"I couldn't believe it when I heard his story. But this is Hong Kong," he said.

Lam's government argued the mask ban is needed to enable police to identify and stop rioters.

But, in a swoop, it risked also criminalizing the vast majority of demonstrators who haven't been torching subway stations, attacking government offices, trashing China-linked businesses or waging pitched battles with riot officers. At peaceful rallies, concerns about being identified are so sharply felt that volunteers hand out surgical masks to protesters who don't have them.

"The fundamental problem is we don't trust the Chinese government," said Chan, the sportswear trader.

Likening its surveillance to "Black Mirror," Netflix's portrayal of a dark high-tech future, he added, "It's not only the battle for Hong Kong, it's the battle for the whole world."