https://en.wikipedia.org/wiki/Zero_Knowledge_Systems
https://www.wired.com/1999/02/zero-knowledge-nothing-personal/
介绍系统
https://www.theregister.co.uk/2001/10/05/zeroknowledge_bags_anonymity_service/
为什么失败？
The sudden suspension may have come as a shock, but not a surprise. Privacy mavens contacted by SecurityFocus said they saw little evidence that Freedom was being used.
“I get only a few hits from ZKS, but I get only a few hits from anonymizers of any kind,” said John Young, a New York City architect who operates Cryptome, a site dedicated to airing documents that deal with the world intelligence community. “What most of us were concerned about was how long they could keep it up.”
ZKS co-founder Austin Hill conceded that Freedom never really took off.
“This was purely a business decision,” Hill said. “Initially we got incredible response for the premium services, but we knew we were dealing with early adopters. But soon we saw the transfer into the mass market just didn’t carry over. The subscription rates really plunged.”
Hill declined to disclose subscriber numbers.
ZKS made a huge splash in the world of privacy-aware Netizens when it announced Freedom in 1998. Back then, the Internet was still riding high. High, too, was anxiety over unscrupulous governments and corporations that might monitor Internet users’ every click and keystroke. The looming combination of Web cookies, server logs and purchase histories, many feared, would lead to the compilation not just of what people bought, but what they wrote, what they read, and every aspect of their on-line identity.