safety – Can an attacker flood the Bitcoin community with pretend transactions?

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We’re in 2050. Individuals present an ever-growing mistrust within the world banking system and begin transitioning to solely utilizing Bitcoin: most corporations settle for it as a type of fee, and other people settle their payments with Bitcoin. Even the child with the lemonade stand down the street accepts Bitcoin as her fee.

Banks are frightened as a result of they’re dropping clients and income. Laws has not managed to guard banks and the smaller ones have already began to close down or present various companies.

Then, the CEOs of Atlantis Financial institution and River Banks, who’re the one wholesome banks remaining give you a plan:

A transaction’s hash can simply be checked. Why not assault the Bitcoin community with an insurmountable variety of pretend transactions! We are going to produce a lot noise, and the community nodes might be occupied with checking our pretend transactions as an alternative of the true ones, a lot so, {that a} appreciable fraction of the entire community computing energy might be dedicated to checking pretend hashes. Actual transaction verification will come to a halt, and other people will not have the ability to do any on a regular basis commerce. They are going to solely be left with one possibility: return again to us.

Right here is my pondering:

  • Bitcoin’s blockchain is rising in measurement.
  • Extra nodes are added to the Bitcoin community.
  • Nodes are getting quicker.

I anticipate this to have an general quadratic impact (within the best-case state of affairs) on this assault: will probably be cheaper for the attacker to generate and submit pretend transactions, however it would even be cheaper for the community to discard the pretend transactions. BUT the blockchain is rising in measurement so in some unspecified time in the future the community might be at drawback.

Listed below are some back-of-the-envelope calculations I made, assuming a fixed blockchain measurement of 15 GB:

  • SHA256 effectivity with at this time’s processors: 45 cycles/byte;
  • So a series of measurement 350 GB, requires 1.6e+13 cycles to be discarded as pretend.
  • With 1 core syncing at 3.5 GHz, this may take 4500 s (1.25 hr).

Are my premises incorrect? Will not there be a turning level, when the price of the most important banks dropping clients be larger than the price of them launching such an assault (in full secrecy)? How can the community defend itself in opposition to these assaults? Positive, one can at all times add extra nodes to the community rising the payment, however will not that additionally flip clients again to the banks (i.e. rendering the assault profitable)?



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