[Cryptography] Bitcoin - closing the coin

[Viktor Dukhovni]

On Wed, Apr 17, 2019 at 02:49:04PM +0000, Garlo Nicon wrote:

> Many times you can read that the Genesis Block is the first block.
> However, when you look at "previous hash" field it is filled with
> zeros. And each new block has more and more leading zeros, as
> difficulty grows. Is it possible that in the future difficulty will be
> very high and miners will create block filled with all zeros? Then,
> this new block will become previous to Genesis Block, making the whole
> block chain a ring like a snake head eating his tail. Will it be
> possible to add any new block then?

See:

    https://en.wikipedia.org/wiki/Wheat_and_chessboard_problem

Finding a SHA2-256 pre-image to 256-bits of zeros is not something
one would expect to compute by chance before the heat-death of the
universe.  Rather, it would require a significant advance in SHA2
cryptanalysis, that enables preimage generation, and breaks all use
of SHA2-256 as a hash function.

-- 
	Viktor.