
Beyond Bitcoin – Part II: Blockchain-based systems without mining [pdf] - grey-area
http://eprint.iacr.org/2016/747.pdf
======
TD-Linux
This paper describes three alternatives to Bitcoin's proof-of-work: proof of
blockchain storage, alternate proofs of work, and proof-of-stake. These ideas
have come up many times in Bitcoin before.

1\. Proof of blockchain storage: This provides no security on its own but has
been suggested many times to prevent SPV mining.

2\. Alternate proofs of work: the idea is to have "cheaper" proofs of work.
One of the proofs of work is a "super-agent", which would basically make a
federated system, not a distributed one. There are also arguments that cheaper
proof of work will just mean proportionally more work is done:
[http://www.truthcoin.info/blog/pow-
cheapest/](http://www.truthcoin.info/blog/pow-cheapest/)

3\. Proof-of-stake:
[https://download.wpsoftware.net/bitcoin/pos.pdf](https://download.wpsoftware.net/bitcoin/pos.pdf)

~~~
duozerk
What I'd love to see (don't know if this has been explored to some extent yet)
would be proof of work but for _useful_ work: think Folding@home or
Einstein@home (BOINC stuff in general) in order to mine a blockchain.

It's very hard to do (if it is even possible) in a non-centralized way though.
Who submits the work ? who validates it has been performed properly ? and so
on.

~~~
UweSchmidt
This is Ethereum: "Mining" generates Ethers, but also runs code, potentially
powering useful blockchain apps.

~~~
duozerk
The current PoW algorithm in ethereum is ethash and does _not_ perform useful
work during coin generation, unless I'm mistaken. You _spend_ ether to fuel
useful work.

Also, Ethereum (forked) aim to switch to PoS soon (ETC may not).

~~~
UweSchmidt
Of course you are right, coin generation is a waste. The part where ether is
changing hands for useful work is at least somewhat "useful".

Best we can hope for is a future blockchain that emphasizes this kind of work
more. A seti@home-coin or cure-cancer-coin is, as you suggested, hard to
implement.

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kragen
The paper is badly written, and so I haven't invested the effort needed to
clearly understand what they're proposing, but I see no indication that the
authors understand the nature of the difficult problem solved by what we are
coming to call Satoshi Consensus. Until they can give a clear description of
the problem and why we struggled to solve it unsuccessfully for 15 years (to
the point that most of us dismissed Bitcoin when it came out) I don't think
it's worth listening to their proposals for solutions.

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tromp
On page 4 the paper states

"if we outline a scenario in which Bitcoin reaches the same value of the
current global fiat money supply, supposing that the energy consumption of
global Bitcoin would grow linearly with its value"

This supposition is highly unrealistic, since the scenario will likely play
out over many decades, during which there will be many block reward halvings
(once every 4 years), which will severely dampen the energy consumption.

Viewed differently, each halving allows the value of bitcoin to double while
maintaining the same energy consumption. At least until the reward drops to a
level comparable to the transaction fees...

~~~
joosters
Why do you believe that? The last couple of halvings appeared to have little
effect on the global hashrate, and so had little effect on the energy
consumption.

The vast majority of Bitcoin mining is done by professionals. I doubt many
people buy thousands of dollars worth of hardware to mine simply for fun.
Miners are looking to profit.

People will mine the coin up until the point at which it becomes unprofitable.
The cost of mining is more or less the cost of electricity (you can amortise
the cost of the mining hardware over time). It makes sense to mine when the
value of a coin is higher than the cost of the power used in mining it.
Electricity cost is proportional to energy consumption. Hence, Bitcoin's
energy consumption is proportional to its value.

~~~
mynameislegion
> Miners are looking to profit.

This is true in a sense, but a majority of the mining is done by Chinese pools
which do sell at a loss to the electricity costs even there. The losses are
acceptable because it is used as a way to get currency out of the country.

~~~
joosters
A majority, you say? Where's your evidence of this, or are you making stuff
up?

Bitcoin is certainly one way to get money out of China, but there has never
been a shortage of ways to do that:

[http://ftalphaville.ft.com/files/2016/03/Screen-
Shot-2016-03...](http://ftalphaville.ft.com/files/2016/03/Screen-
Shot-2016-03-03-at-13.54.37.png)

------
sktrdie
Can anyone provide a TLDR? All I can see in the conclusion is: "We expect to
develop a prototype of a blockchain-based system with the raffle protocol in
the near future.". So their alternative to reaching consensus is a raffle
protocol? And in raffle protocol section I read "among a set of eligible
agents" and "relying on a trusted “global clock” service". Seems quite
centralized if you ask me.

~~~
homero
Sounds like a hybrid pos with a centralized key giveaway

------
aeijdenberg
If you accept that for many uses of publicly verifiable data structures that
centralization is actually OK (and actually often a good thing, as it matches
well how most democratic societies function), then there are other simpler
alternatives to proof-of-work that still give many of the same benefits.

See for examples the append-only logs used in Certificate Transparency
([https://www.certificate-transparency.org](https://www.certificate-
transparency.org)), and a more generalized hosted form provided by Continusec
([https://www.continusec.com](https://www.continusec.com)) that builds on the
same principles. (disclaimer: founder of Continusec)

~~~
runeks
The difference is that this data structure defines who's rich and who isn't
(literally). There is a whole lot more incentive to tamper with such a data
structure than basically any other data structure in existence.

------
pietrod
mining= energy proof of burn, a way to bootstrap value in a cryptocurrency, at
least in bitcoin, see "commodity". "The steady addition of a constant of
amount of new coins is analogous to gold miners expending resources to add
gold to circulation" it's a feature.

This is regarding first 2 chapters where it compares it with fiat saying it
could become 802.4% more costly, right comparison is with gold indeed like in
[https://www.bitcoin.fr/public/divers/docs/Estimation_de_la_d...](https://www.bitcoin.fr/public/divers/docs/Estimation_de_la_durabilite_et_du_cout_du_reseau_Bitcoin.pdf)

Expect a tldr of chapter 5, will check here back tomorrow if there is any.

Actually I'm happy they are working on an actual prototype.

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itsnotlupus
I wonder how this relates to ethereum's Casper proof of stake mechanism.

------
jamisteven
Blows my mind how many banks are throwing money at this when they dont
understand the least of the underlining technology just because they want
their hands on a potential rival fiat digital currency.

~~~
digi_owl
No, what they want is a interbank ledger without the need of a clearing house.

------
keredson
TL;DR... see git

