[bitcoin-dev] Chain width expansion

[Braydon Fuller]

On 10/12/19 10:56 AM, Joachim Strömbergson via bitcoin-dev wrote:

> [...] First you provide proof of your best block height via coinbase [...]

So I don't think you can use the height in the coinbase for that
purpose, as it's not possible to validate it without the previous
headers. That's common for more than just the height.

> [...] to generate much longer chain with superslow timestamp increase (~5 blocks in 1 second) without increasing difficulty (i.e. staying at min. diff.). [...]

In that case, it would take about 7 minutes of block time seconds for
the next retarget period, every 2016 blocks, and the difficulty would
adjust. The difficulty would adjust in that case as if 2 weeks of blocks
had been mined in 7 minutes. For the difficulty to remain the same the
time between blocks needs to be 10 minutes.