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Article author here. Supermajority attestations and block finalization, as well as withdrawal queues, prevent long-range attacks. To attempt to reorg a finaliz

Article author here. Supermajority attestations and block finalization, as well as withdrawal queues, prevent long-range attacks. To attempt to reorg a finalized block (blocks are generally finalized after 6 minutes) you have to commit to losing 1/3 of total staked ether, currently several billion dollars. The only participants who can equivocate (vote for two blocks at the same height) are active validators so there is significant economic value at risk to pursue such an attack.

naveen99 4y ago
Wasn’t there a recent attack on solana/ solend, where the attacker was willing to lose more than 30% for the chance to cash out and crash solend at the same time ?
- 0xfoobar 4y ago
  The Solend drama was at the app-layer rather than the protocol-layer. Solana also runs PoS but its variant is a bit more handwavy and weaker imo, slashing rules are applied in a post-hoc human decision-making process rather than clear rules enshrined within the protocol.
camjohnson26 4y ago
Theoretically, if somebody forked the Ethereum PoS blockchain and faked timestamps to catch up to the real chain’s height, would there be any way to know which was the original other than community agreement? Seems like PoW makes it impossible since duplicating the original chain is prohibitively expensive. Not challenging the solution, just genuinely curious in how PoS works.
- 0xfoobar 4y ago
  Great question, it's not timestamps but attestations (signed validator votes for pairs of checkpoint blocks) that determines the canonical chain head. This fork choice rule, known as LMD-GHOST, is different from PoW which has a "greatest difficulty" rule for determining the canonical chain. There is some element of bootstrapping who the original validator set was, known as "weak subjectivity". There's a great post from Vitalik exploring this further at https://blog.ethereum.org/2014/11/25/proof-stake-learned-love-weak-subjectivity/ https://blog.ethereum.org/2014/11/25/proof-stake-learned-lov...
  - camjohnson26 4y ago
    Awesome, thanks!

naveen99 4y ago

Wasn’t there a recent attack on solana/ solend, where the attacker was willing to lose more than 30% for the chance to cash out and crash solend at the same time ?

0xfoobar 4y ago
The Solend drama was at the app-layer rather than the protocol-layer. Solana also runs PoS but its variant is a bit more handwavy and weaker imo, slashing rules are applied in a post-hoc human decision-making process rather than clear rules enshrined within the protocol.

camjohnson26 4y ago

Theoretically, if somebody forked the Ethereum PoS blockchain and faked timestamps to catch up to the real chain’s height, would there be any way to know which was the original other than community agreement? Seems like PoW makes it impossible since duplicating the original chain is prohibitively expensive. Not challenging the solution, just genuinely curious in how PoS works.

0xfoobar 4y ago
Great question, it's not timestamps but attestations (signed validator votes for pairs of checkpoint blocks) that determines the canonical chain head. This fork choice rule, known as LMD-GHOST, is different from PoW which has a "greatest difficulty" rule for determining the canonical chain. There is some element of bootstrapping who the original validator set was, known as "weak subjectivity". There's a great post from Vitalik exploring this further at https://blog.ethereum.org/2014/11/25/proof-stake-learned-love-weak-subjectivity/ https://blog.ethereum.org/2014/11/25/proof-stake-learned-lov...
- camjohnson26 4y ago
  Awesome, thanks!