Is it possible to get stuck with a block that nobody can mine?
Is it possible to get stuck with a block that nobody can mine? The hash of a bitcoin block is generated from: Block version number (partially fixed*, 4 bits) Previous block hash (fixed, 256 bits) Merkle root (not fixed, 256 bits), Time (not fixed, 4 bits), Bits (partially fixed*, 4 bits), Nonce (not fixed, 4 bits). So, the block hash is generated from 528 bits. You can change 264 bits freely to try to have a hash that matches the current diff, and 264 bits are immutable. Is there a property on the SHA-256 function that asserts that on these 264 bits of freedom, one combination will give us a hash that is matches the diff requirements? If not, does that mean that the blockchain could get stuck on a block because nobody can mine on it? * "Partially fixed" values could be overriden by software updates for example. I assume that partially fixed values are fixed to simplify. http://ift.tt/2lHqcjH