The mask ban in Hong Kong did not stop the protesters from wearing masks. So the Chinese state security is using technology to identify protesters.
A large number of Chinese State Security personnel from mainland China dressed like protesters are mixing in the crowd. A small piece of equipment in their backpacks can “read” protesters’ information from their Hong Kong identification cards and cellphones within a reading range.
Once the undercover cops identify the person, more information will be collected via web crawling, AI and Big Data on social media for cross-references. The identified protesters and all their buddies on social media will be kept under surveillance by the police.
Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects. The tags contain electronically stored information.
Hong Kong government promised to safeguard Hong Kong residents’ information stored in the government’s database. So the mainland state security is violating Hong Kong people’s privacy by stealing their information using “card skimming”.
However, RFID blocker sold on Amazon claims to offer protection against card skimming.