From my knowledge a header hash will be calculated like this:
- serialize all header fields, including "the nonce"
- hash the serialized header once
- hash the hashed serialized header again
- check if the result is below the target
- if no: choose a different nonce and start over
I'm referring to this site that allows you to enter some header data and calculate the header hash:
The site already calculates the serialized header that I have to use for the hashing process:
So running this serialized header through SHA256 for two times gives me this hash after the first iteration:
And hashing this again would return:
But this is not the actual hash for this block header. Apparently, because starting with a 9 seems not be very difficult. That is the correct header:
So I'm wondering, what additional step I'm missing here?