Christine worked quickly to transform a promotional poster originally designed for global telecoms company Three Hong Kong. The company’s name is homophonic with “Free Hong Kong” — the message Christine and a group of graphic designers are committed to spreading throughout the city — which is now illegal to express. On the face of it, the 14 characters on the poster refer to a technological revolution brought about by the city’s fiber broadband network. But look closely, and you’ll see that they contain the eight characters that make up the protest’s now-outlawed rallying cry: “Liberate Hong Kong, the revolution of our times.”

Christine, who asked to be identified by a pseudonym to protect her identity, and her colleagues have made publicity posters for Hong Kong’s pro-democracy protest movement since it first rose up in June 2019. But now this work has been forced underground. Coded messages have replaced the movement’s mantras. On June 30 — just one day before the anniversary of Hong Kong’s handover from Britain to China — China’s rubber-stamp parliament passed a wide-reaching national security law criminalizing acts of secession, subversion, terrorism, and collusion with foreign forces.

The legislation, which stipulates that offenders could face up to life imprisonment, was introduced without the input of Hong Kong’s own Legislative Council. Full details were released only when it went into force, raising fears among critics that Beijing has fundamentally eroded the high degree of autonomy the city was promised when it came back under Chinese rule just 23 years ago. 

Protest plans, summaries of news events, motivational messages calling on protesters to fight on — all have come across Christine’s desk, and now all risk falling on law enforcement’s radar. Christine and other protest supporters have regularly uploaded posters to Facebook and Instagram, where they could reach everyday Hong Kongers. But the law has extended the power of Hong Kong’s police to be able to censor online speech and compel internet providers to share user data.

Read: How a raucous internet forum became ground zero for the Hong Kong protests

Now, activists like Christine are taking extra precautions: keeping a VPN on at all times to conceal their locations, encrypting messages, and regularly swapping out SIM cards. “I am most worried about internet security,” says Christine. “We now feel very uncertain, but this proves that what we have been doing has really shaken up the regime.”

Hong Kongers who have expressed support for the leaderless pro-democracy protests, which largely organized through online platforms like LIHKG, a Reddit-like forum popular among protesters, and on messaging services like Telegram, now confront a reality in which speaking their minds could become a criminal act. In the days since the law was enacted, accounts have disappeared from Twitter and Telegram. Conversations have been deleted from WhatsApp.

“I am most worried about internet security. We now feel very uncertain, but this proves that what we have been doing has really shaken up the regime.”

Two days after the law came into effect, the government declared one of the most popular protest slogans — “Liberate Hong Kong, the revolution of our times” — illegal because it contained “separatist intent.” Anyone uttering those words may now be accused of subverting state power. Schools have ordered students not to sing “Glory to Hong Kong,” the unofficial anthem that had echoed across the protests. In place of signs bearing slogans, protesters have started carrying blank sheets of paper.

Hong Kong’s protest movement first materialized as a demonstration against a proposed extradition law with China and grew to encompass calls for universal suffrage and investigations into police brutality. The protests engulfed the city last summer, bringing millions into the streets chanting and carrying banners bearing slogans like “Free Hong Kong,”and “Hong Kong independence” and calling for Chief Executive Carrie Lam to step down.

While Hong Kong officials have insisted the national security law does not have retroactive power, they have also warned that a person’s online records could be used as evidence against them. Tam Yiu-chung, a pro-Beijing politician who is Hong Kong’s only delegate to the Standing Committee of the National People’s Congress, China’s committee responsible for drafting the law, told Rest of World: “If you violate the national security law after it comes into effect, all your previous actions should be taken into consideration in court, as it may confirm that you have always been damaging national security.” 

Beijing has said the law is needed to restore stability in Hong Kong, but many Hong Kongers and human rights officials — including the Office of the United Nations High Commissioner for Human Rights — argue that the vaguely worded law could allow authorities to silence dissent by allowing arbitrary interpretation and enforcement.

Read: Singapore is trying to shut down the last free space for dissent

Charles Mok, a pro-democracy lawmaker who represents the IT sector in the city’s legislature, says he is worried the law may further limit the city’s internet freedom. “I am concerned about the broad and vague nature of the law as it may be applied to the internet and other media,” he says, adding that residents are unsure where authorities might draw the red line.

One activist, who goes by the name Bobo and asked Rest of World not to use her full name, has already witnessed firsthand the chilling effects of the new law. Bobo currently manages one of the most influential Telegram channels on the Hong Kong protests, Bobo channel. (Bobo means “baby” in Cantonese.) When she logs on, she’s cautious to take extra steps to stay anonymous. “I am now swapping my mobile SIM cards regularly, and I turn on my VPN whenever I go on the internet,” she says.

For the past year, her channel has provided regular updates on the latest protest plans and police movement across the city. To date, her channel has accumulated about 140,000 subscribers, and since last summer, it has been inviting submissions from users on the latest happenings across the city. At the height of the protests, she often stayed up past midnight to process all the leads and summarize them on the channel.

The national security law immediately curbed this momentum. “I lost about 10,000 followers within one day, after the national security law came into effect,” she says. “I heard from my sources that police already have a record of Telegram users who actively supported the protests. But I can’t worry too much, because I already expected what I might face the first day when I decided to start my work.”

Lam Yik Fei/The New York Times via Redux

While some Hong Kong protestors have decided to delete their online presence to avoid falling afoul of the new rules, many others — including Bobo and Christine — have now turned to VPNs, which mask a user’s internet identity. 

In a statement to Rest of World, the internet security provider NordVPN said it has received a huge increase in inquiries from Hong Kong users since the law was first announced in late May. “Back then, the number of inquiries went up 120 times within a couple of hours compared to the day before,” said Laura Tyrell, the company’s head of public relations. She added that it is “not unusual” to see people turning to privacy tools like VPNs when governments announce an increase in surveillance or internet restrictions. Surfshark, another VPN provider, also said that it reported a week’s worth of sales in the Hong Kong market within just one hour of the law’s  announcement.

Lawmaker Mok says VPN may be the “minimal measure” internet users can take to protect their online security. But he adds that other precautions — such as choosing which social media platforms to use and ensuring the security of their physical devices — are also equally important if they want to maintain their anonymity online. 

Some of the world’s leading communication platforms — including Zoom, Facebook, WhatsApp, and Twitter — confirmed to Rest of World that they have suspended data requests from Hong Kong law enforcement agencies. Telegram told Hong Kong Free Press that it had paused similar requests, and LIHKG implemented a two-factor authentication program for users just weeks before the law was passed. But while companies have suspended these requests for now, no one knows if they will stick to their commitments, and observers have warned that these tech giants might have to confront pulling their operations in Hong Kong if they don’t cooperate with authorities. 

Many Hong Kongers have also shown a greater level of creativity in finding ways to circumvent official censorship, echoing how dissidents in mainland China have used hidden meanings to convey political messages.

Christine says that, after the government outlawed the “Liberate Hong Kong” slogan, designers have been using clever means to keep it alive. Designers adopted the propaganda-arts style common during China’s Cultural Revolution in the 1960s and painted a group of Red Guards waving red flags under the smiling leader. They borrowed Mao’s famous revolutionary slogan — “Revolution is no crime, to rebel is justified” — for the modern context, to implicitly encourage fellow protesters without crossing the official line. Activists believe authorities will not charge them with subverting state power if they borrow slogans and images from the country’s founder.

This creativity has been on display in Hong Kong’s social media beyond poster design. “Glory to Hong Kong” — written during the protests and the de facto anthem of protestors — contains sensitive words such as “revolution of our times.” In a viral Facebook post, the song’s composer suggested a new set of lyrics that contains only numbers but closely resembles the tone of the original lyrics when sung in Cantonese. On LIHKG, a protestor proposed using the first line of China’s anthem — “Arise, ye who refuse to be slaves” — as an alternative slogan for protesters under the new law. The post received hundreds of comments and was visible in the forum’s “popular” page.

While authorities are clamping down on free speech, Christine says she and other activists have continued to voice their dissent to keep the hope of freedom alive. The group has continued to publish posters online, while some of her teammates have now designed materials for the protest’s international lobbying work. “You may be able to criminalize a speech, but you will never be able to erase the spirit of the Hong Kong nation,” Christine says, adding that authorities will never imprison people’s minds. “We will keep on the fight and wait until the day when we are finally free.”