It will not allow you to delete all users of the system, but will give you the opportunity to influence its operation.
Carefully, the text contains spoilers for the eighth episode of the fifth season of the series.HBO Frame
The final series of the fifth season of “Silicon Valley” was devoted to the ” 51% attack ” – a situation where most of the block-network is owned by one group of organized users, which allows them to influence the operation of the system. According to the plot of the episode, the rivals of the “Rat-catcher” conspire to take possession of 51% of the company’s decentralized Internet. One of the start-up workers says that this will allow them to “delete all our users, applications of our developers and bring down our currency.”
However, in fact, it’s not quite true: the “51% attack” has already been applied in the real world on small crypto-currencies like Krypton and Shift, which are clones of the Etherium. Both currencies were attacked by one group, calling itself “Team 51”.
When the attackers obtained a majority in Krypton and Shift, they sent their creators a demand for redemption with the threat of disrupting the network if they were not paid. The danger was real: a group of miners controlling more than 50% of the network can stop payments between users or make some past transactions invalid, as if users did not spend money.
For small crypto-currencies, rewriting transactions in public records can cause serious damage, because it will affect the legitimacy of all transactions – and this can kill the currency. This problem has no solution, since such groups of miners use the fundamental principle of building a decentralized network.
However, cryptographer from the University of Cornwall Emin Gün Sierer (Emin Gün Sirer) told The Verge that the “51% attack” can not cause such serious damage, as shown in the “Silicon Valley”. He argues that, although its application could indeed bring down the “Crypt”, but would not affect users or developers’ programs.
Miners controlling 51% of the network do have a lot of power, but they do not have the ability to change existing system rules or grab money. They can rewrite the used block in a limited format: without adding any non-existent transactions, but by skipping any already executed transactions of their own choice. And they, of course, can not change any of the existing rules.
Emin Gun Sayerer
The expert noted that sometimes the authors of films and serials sacrifice technical accuracy for the sake of drama, and this is exactly the case.
“Attack 51%” is rarely discussed outside the crypto-currency community, although it is a serious threat even for the largest crypto currency – bitcoin. About 70% of all bitcoin miners are concentrated in China, so experts even predicted how the government of the country in theory can destroy the crypto currency, without causing any suspicion.