The leaks · 51 / 86
51% attacks and chain halts
A chain can fail as a chain. An attacker with enough mining power or stake can rewrite recent history. A small validator set can halt, or be ordered to halt.
Rewriting the recent past
Payments that looked confirmed can be replaced if the attacker builds a heavier history. Exchanges wait for many confirmations because of this. A merchant who accepts one confirmation on a small chain is exposed.
A halt
If validators stop, your transfer waits. If a few companies run the validators, a court or a government can speak to those companies. Decentralised is a measurement, not a sticker.
The check is who can stop the chain, not the adjective in the marketing.
Check yourself
Does a logo that says decentralised prove a chain cannot be halted?
No. Count who actually produces the blocks.
After this you can ask how many independent parties would have to stop before this chain stops.