Reverse engineering block propagation
- Target Hash is based on a recurrently adjusted difficulty. For, example the TH is a 256-bit string with 17 leading zeros.
- The hash can be interpreted as follows SHA_256(SHA_256(Block_Header, n). Where n is the field of bits known as the nonce.
- Increment n if H < TH
“Because the nonce is only 32 bits, after exhausting all the nonce possibilities (about 4 billion), the mining hardware changes the block header (adjusting the coinbase extra nonce space or timestamp) and resets the nonce counter, testing new combinations.”