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So im mainly thinking in the very early days of bitcoin when the networks compute power was minimal.

What would happen if say a big organization with exponentially more compute power than the network, were to join for a little while, raise the difficulty, and then promptly leave?

Since the difficulty is only re-calculated every 2016 blocks, couldn't this effectively stagnate the entire network since mining 2016 might no longer be feasible?

Is there something in the protocol that prevents this? also does such an attack have a name?

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In the early days of Bitcoin, sure. Today, not so much.

Back when Bitcoin was only being mined by a few individuals on their home PCs, it would have been "relatively" easy to use a supercomputer, mine for one difficulty adjustment period, and then stop mining, leaving the network in a state where mining another 2016 blocks could easily take years. (Correction: It would take more than one difficulty adjustment period to do that.) What the community could then do is to deploy a fork that would deliberately ignore the longer chain, making mining possible again.

Today, even the largest general-purpose supercomputers cannot compete with miners using ASICs built specifically for mining bitcoin. If you wanted to get orders of magnitude more computing power than the rest of the network, you would need orders of magnitude more ASICs, at a time when ASIC manufacturers barely keep up with demand from actual miners.

Of course, if you have more computing power than the rest of the network combined, you can execute a 51% attack, which might be a lot more damaging to Bitcoin than the attack you've described.

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  • actually i am asking this because i am developing my own little hobby blockchain based cryptocurrency with some of my friends. Currently even though we are all making transactions here and there, i am the only one running a miner on the network. The miner is only a small raspberry pi b with very little compute power. Thats why i am worried someone will come along with alot more compute power and stagnate our little hobby currency. But i guess there is nothing i can do? other than to hard fork if it ever happens
    – stav
    Dec 15, 2021 at 8:14
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    As an interesting side note, the largest downward difficulty adjustment in Bitcoin was 28% in May-June 2021 when China banned mining.
    – Vojtěch Strnad
    Dec 15, 2021 at 8:18
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    @stav A cryptocurrency with a single mining Raspberry Pi is probably much worse in terms of security than a centralized currency with a single server holding everyone's balances. Of course if it's a hobby currency with no real value then security really doesn't matter.
    – Vojtěch Strnad
    Dec 15, 2021 at 8:26
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    It would be hard to increase the difficulty so far that "mining another 2016 blocks could easily take years" in one dififculty period, since each adjustment is capped to a 4× increase. It would be possible if a huge amount of mining power mined multiple consecutive difficulty periods and increased the difficulty by e.g. 64× or even 256×.
    – Murch ♦
    Dec 20, 2021 at 17:15
  • @Murch Thanks for the correction, I didn't know that.
    – Vojtěch Strnad
    Dec 20, 2021 at 17:56

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