Why don't we have more checkpoints? #21886

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src/chainparams.cpp:146 has few checkpoints for the mainnet using a table of block and blockhash. Why does it end at block 295000?

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Either add a comment with an explanation for given number checkpoints or add checkpoints at an agreed block interval.

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See this answer on bitcoin stackexchange.

I think they are not so useful and if we need to use them, it means the system is already broken.

It is not uncommon for people to add additional checkpoints to their nodes. For example, Bitcoin Knots, which is patched version of Bitcoin Core by @luke-jr, adds additional checkpoints.

Could make sense to mention briefly in the code what https://bitcoin.stackexchange.com/a/70824/3576 says?

I think so, @MarcoFalke.

@brunoerg Shall I remove the checkpoints (and the validation code) to avoid the confusion?

@abhiShandy No, they're still needed to prevent low-difficulty header spam. It's not a particularly strong attack, but without checkpoints it's trivial. The current checkpoints suffice to make it sufficiently expensive.

Closing since the questions seems to be answered sufficiently.

Checkpoints are currently required, but see #25725 for a glimpse into the future.