[cryptography] NIST Randomness Beacon

Natanael natanael.l at gmail.com
Mon Nov 11 14:14:42 EST 2013


Proof-of-work, just like Bitcoin itself uses for hashing? See hashcash as
well. Require that the message in question is hashed together with a random
value, with an output that matches a given pattern. And specify that one
part of the message has to be the hash of a Bitcoin block from the given
time period.

- Sent from my phone
Den 11 nov 2013 17:43 skrev "CodesInChaos" <codesinchaos at gmail.com>:

> On Sun, Nov 10, 2013 at 9:54 AM, Andy Isaacson <adi at 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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