“The government’s arbitrary power is reflected, or coded, in the app,” Ms. Wang said, adding that the system “is programmed to consider vague, broad categories of behaviors, many of them perfectly legal, as indicators of suspiciousness.”
Intelligence agencies in many countries use sets of behavior to single out individuals for greater scrutiny. But China has taken that approach to an extreme, treating the Muslim population in Xinjiang as suspect from the start and defining suspicious behavior in sweeping terms, including peaceful religious activities such as making a donation to a mosque.
The Chinese government has defended the surveillance program, saying it has improved security in the region, and says the indoctrination camps in Xinjiang are job training centers. Hikvision has denied “any inappropriate actions in Xinjiang,” and C.E.T.C. declined to comment when reached by phone.
C.E.T.C. traces its roots to the military research labs that helped build China’s first nuclear bomb, satellite and guided missile. Established as a state defense manufacturer in 2002, it soon expanded into civilian security matters, working with Microsoft, for instance, to create a version of Windows that meets the government’s internal security requirements.
In recent years, it turned to Xinjiang.
The Communist Party, which took control of the region in 1949, has long been wary of the Uighurs, whose Turkic culture and Muslim faith have inspired demands for self-rule, and sometimes attacks on Chinese targets. State investment in surveillance took off a decade ago after anti-Chinese rioting in the regional capital, Urumqi, killed nearly 200 people.
The real bonanza of security contracts came after Xi Jinping took the helm of the party in late 2012. Spending on internal security in Xinjiang totaled nearly $8.4 billion in 2017, six times as much as in 2012, including funds for surveillance, personnel and the indoctrination camps.
Hikvision has received contracts in Xinjiang worth at least $290 million for its cameras and facial recognition systems. Another company tapping into Xinjiang’s security gold rush is Huawei, the Chinese tech giant that the United States has described as a security threat. It signed an agreement last year with the region’s police department to help officers analyze data.