A police investigation is underway over the "mining" of cryptocurrency in which a number of people allegedly used other people's personal computers without permission, investigative sources said.
Investigators suspect that the case is a violation of the law banning use of computer viruses. If police press charges, it will be the first case in Japan where illegal use of computers in cryptocurrency mining would become a criminal case. The incident is being pursued jointly by multiple prefectural police departments including those in Kanagawa, Chiba and Tochigi in central Japan.
According to investigative sources, people involved in the case set up websites in the fall of 2017 to install a program on viewers' computers and use the machines for mining the Monero cryptocurrency.
Obtaining cryptocurrencies, or digital currencies, is often likened to electronically "digging up" gold using computers. The currencies are given as a reward to contributors of computing power used to calculate if all cryptocurrency transactions are legitimate. The more computing power one has, the faster one can receive cryptocurrencies, and this can serve as motivation to use other people's computers without consent. Exploited computers become slow and consume large amounts of electricity as they have to do the extra calculation for cryptocurrency mining.
Investigators apparently judged that this case can be criminally pursued because the installation of the mining program was done without the consent of the computer owners and those machines were forced to function in ways not intended by their legitimate owners. Police do not intend to press charges over websites that clearly say they are placing mining software on visitors' computers.
Police have investigated three individuals including a website designer, and one of them was ordered by the Yokohama Summary Court to pay 100,000 yen for illegally storing a computer virus. The defendant, however, argues that it was not a virus as it uses a method similar to distributing advertisements online. The case is set to proceed to a fully fledged trial at the Yokohama District Court.
The program in question is called Coinhive. It distributes 70 percent of rewards coming out of mining to website owners who introduced the software, and the remaining 30 percent to its developer. Computer security companies such as Trend Micro have warned users about Coinhive, saying it is being used for malicious purposes. The company detected 181,376 terminals running mining software from January through March 2018 in Japan, marking an explosive increase from 767 in the same period a year ago.
Coinhive is easy to introduce to websites and has played a role in the spread of cryptocurrency mining. Its developers promote the program as a means to make income without relying on advertisements, and even the United Nations Children's Fund (UNICEF) placed the program on its donation site. If visitors agree to the use of their computer power by Coinhive, profits from mining go to UNICEF.
This kind of arrangement is similar to assigning online ads to certain computer users. Following a search for hotels, internet users often see hotel ads even when they are visiting websites not related to accommodation because view records are used for ad distribution. Coinhive utilizes a similar system for mining, using computer power from different users.
Police investigators decided to press charges in the latest case targeting websites without clear notices about mining, because they judged that users remain in the dark about the use of their computer power, while users often can deny ad distribution to their computers. But Lawyer Takashi Hirano, who represents the defendant in the Yokohama District Court case, intends to wage a full-scale legal fight, saying, "It's not right that only Coinhive is painted as the bad guy."