The protest movement in Hong Kong has come up with creative ways to outfox the police.

Activists have developed a sign language which lets them request supplies and warn of specific dangers.

Such codes exist in other activist movements, but the Hong Kong one appears far more sophisticated.

They have come up with other methods to frustrate police, including smothering tear gas canisters with mud, and using hard-to-track technology.

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In the months since hundreds of thousands of Hong Kong residents took to the streets to protest a law allowing legal extradition to mainland China, they have adopted sophisticated security and communication techniques that have kept the protests alive.

Members of the protest movement have pushed back, even as police attack transportation hubs to disrupt travel, and deployed ink-dyed water cannons to disperse protesters while also marking them for later arrest.

With no specific leadership organization to target, Hong Kong's security forces have struggled to disrupt the protests, which at times have paralyzed the former UK colony, which returned to Chinese administration in 1997.

Seeming to live up to their motto — "Be Water!" — the apparently leaderless protest group has developed multiple communication techniques that allow it to exploit its leaderless makeup and leave authorities struggling to get a grip on it.

Circulating online is a complex list and chart of agreed-upon hand signals for use by protesters on the streets during direct action against the authorities.

The image can be seen in full via the link below, a Medium blog post published by Rory Byrne, the cofounder of the digital security company Security First.

The exact origin of the image is not clear — it appears to have been created by Hong Kong protesters and circulated among protest groups via the secure app Telegram.

Very basic signals are commonplace in street protests because of the disruptive effects of tear gas and loud noises, and the need to communicate rapidly.

But the Hong Kong list is far more sophisticated and useful than usual.

Their signs can distinguish between police use of pepper spray and tear gas, warn of danger and even ask for specific medical supplies and equipment. There are signs for anything from bandages to allen keys.

Protesters have also shared extensive information on how to use Google Drive or Apple's Air Drop feature to pass detailed information — from maps to protest schedules — without one-to-one communication, making it almost impossible for police to trace.

Without any central depot for orders and information, security forces have consistently failed to stop demonstrators from self-organizing and quickly responding to pressure.

One common piece of information transmitted to protesters is how to disable the facial recognition software that unlocks an iPhone's encryption, to prevent being scanned with one's own phone upon arrest so that police might access its data.

In another widely-circulated video, a masked protester wielding a thermos filled with mud demonstrates how to neutralize a live tear gas canister.

The start of the new school year Monday has sparked the latest round of protests in the city leaving the streets covered in tear gas and demonstrations.

And on Tuesday, Reuters obtained and released a recording of Hong Kong's chief executive Carrie Lam speaking to the city's business leaders.

In the footage she admits that she misjudged popular anxiety about Chinese rule, but that she believes the central Chinese government will ultimately not use its military to crush the protest movement.