China will soon have the world's most secure major computer network, making communications between Beijing and Shanghai impenetrable to hackers and giving it a decisive edge in its quiet cyberwar with the United States.

In two years' time, a fibre-optic cable between the two cities will transmit quantum encryption keys that can completely secure government, financial and military information from eavesdroppers.

The new fibre optic cable will initially be used mostly for money transfers by ICBC. Credit:Bloomberg

"We learnt after the Edward Snowden affair that we are always being hacked," said Professor Pan Jianwei, a quantum physicist at the University of Science and Technology of China (USTC) in Hefei, who is leading the project. "Since most of the products we buy come from foreign companies, we wanted to accelerate our own programme," he added. "This is very urgent because classical encryption was not invented in China, so we want to develop our own technology."

The $110 million cable, which is being funded by the central government and has been supported by the Central Military Commission, will initially mostly be used for money transfers by ICBC, the world's largest bank.