(Top posted, so sue me, my text explains itself without the history).
Thats a big cc list. I think you could create a beacon with bitcoin hash
chain by having miners reveal a preimage for 6 old, consecutive blocks where
the newest of the 6 old blocks is itself 6-blocks confirmed. (ie reveal
preimage on blocks 7-12. The xor of those preimages defines a rolling
beacon (new output every block, just with reference to blocks 7-12 relative
to the current block depth).
The security against insider foreknowledge is not fantastic, as its relating
to the trustworthiness of the 6 random miners (which have probabilty of
winning relating to hashpower, which doesnt always relate to
trustworthiness).
Adam
On Mon, Nov 11, 2013 at 05:42:54PM +0100, CodesInChaos wrote:
On Sun, Nov 10, 2013 at 9:54 AM, Andy Isaacson <a...@hexapodia.org> wrote:
For example, suppose you use the low bits of the bitcoin blockchain
hash. An attacker with 10% of the hash power could probabilistically
attack such a system by chosing blocks with a specific value in those
bits;
This can be avoided by running a sequential computation based on that hash.
For example by hashing it 2^40 times. Obvious downside is that verifying
that the computation was performed correctly is just as expensive (but
parallelizable).
Perhaps there is a function that's sequential and slow in one
direction and fast in the reverse direction.
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