[Cryptography] Electronic currency revived after 20-year hiatus

[Natanael]

Den 18 aug. 2016 07:11 skrev "Jerry Leichter" <leichter at lrw.com>:
>>
>> Not trying to make it seem magic. Just emphasizing that the approach is
unique.
>
> There are many unique idea out there.
>>
>> > 1.  The Byzantine Generals problem was never considered unsolvable.
In fact, the very paper that introduced it also provided a solution.
>>
>> I guess I should have added more detail.
>>
>> All previous solutions required gatekeepers, because they all failed if
the adversary could perform a Sybil attack (flood the network with
nodes)....
>
> I'm not sure what problem you're describing, but it's not the Byzantine
Generals problem.

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

It is the generalized one as described here:

> The objective of Byzantine fault tolerance is to be able to defend
against Byzantine failures, in which components of a system fail with
symptoms that prevent some components of the system from reaching agreement
among themselves, where such agreement is needed for the correct operation
of the system. Correctly functioning components of a Byzantine fault
tolerant system will be able to provide the system's service, assuming
there are not too many faulty components.

> The problem is complicated by the presence of traitorous generals who may
not only cast a vote for a suboptimal strategy, they may do so selectively.

Bitcoin trades "not too many faulty components" for "not too many malicious
CPU cycles". *You can't cheaply introduce a majority of nodes voting for
your own desired outcome*. It also uses broadcasts for communication
instead of needing to talk to any given set of peers.

The nodes WILL agree on which chain has the most accumulative proof-of-work
as long as they know of the same forks, and as long as they've got
different amounts of accumulative proof-of-work (although not immediately
guaranteed they do when of equal length, across just a few blocks, it is
overwhelmingly likely over time given the difficulty retargeting
mechanism).

As I explained before, it does this so that you don't need to rely on a
central gatekeeper. And not having one is why it got so much interest.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.metzdowd.com/pipermail/cryptography/attachments/20160818/282d0e51/attachment.html>