Early last year, Ivy*, a Chinese student living in Germany, got a phone call from the police. At first, she thought it was a scam. An officer said they needed her help with an investigation involving someone she once knew. What followed turned her world upside down.The police told her that her former boyfriend, identified in court documents as Tong Z, had been investigated for sexual assault and covert photography. Then came the tougher blow: police showed her a number of nude photos Tong Z had secretly taken of her while she was asleep. Ivy, now 27, recognised herself, though...