One of the fundamental assumptions of blockchains, whether public or private, is that 51% of actors, especially miners, are honest. Logically, the more actors there are, the more the assumption stands. However, numerous bitcoin developers, including Gregory Maxwell, Peter Todd, Luke-Jr and others, have stated that bitcoin mining is centralized in two or three individuals.
The invention of ASICs, in combination with economies of scale (although some research suggests after a certain point – around 25% – it becomes more economical to have less hashing power) has led to giant mining farms in remote areas of China where electricity is cheap, making Bitcoin mining highly profitable. It is, however, much more profitable to be rewarded for mining, through blocks or fees, rather than maliciously attack the network, but the option is there and facts can change.
A new paper [PDF] from university researchers based in Shanghai and Virginia claims to have a solution which secures the network even if 51% of miners are malicious. The highly technical paper, extending more than 30 pages, opens by stating:
“On top of Bitcoin’s