> @befreeandopen " An attacker can calculate whether or not she can prolong
> this chain or not and if so with what timestamp."
>
> The scenario you describe would only be likely to happen at all if the
> malicious actor has a very large fraction of the stake - probably quite close
> to 50%. At that point, you're talking about a 51% attack, not the nothing at
> stake problem. The nothing at stake problem is the problem where anyone will
> mint on any chain. Its clear that if there's a substantial punishment for
> minting on chains other than the one that eventually wins, every minter
> without a significant fraction of the stake will be honest and not attempt to
> mint on old blocks or support someone else's attempt to mint on old blocks
> (until and if it becomes the heaviest chain). Because the attacker would need
> probably >45% of the active stake (take a look at the [reasoning
> here](https://github.com/fresheneesz/ValidatedProofOfStake#security-the-minimum-cost-of-attack)
> for a deeper analysis of that statement), I don't agree that punishment is
> not a sufficient mitigation of the nothing at stake problem. To exploit the
> nothing at stake problem, you basically need to 51% attack, at which point
> you've exceeded the operating conditions of the system, so of course its
> gonna have problems, just like a 51% attack would cause with PoW.
This is not at all the case. The attacker benefits using the described
technique at any size of the stake and significantly so with just 5% of the
stake. By significantly, I do not mean that the attacker is able to completely
take control the network (in short term), but rather that the attacker has
significant advantage in the number of blocks she creates compared to what she
"should be able to create". This means the attacker's stake increases
significantly faster than of the honest nodes, which in long term is very
serious in PoS system. If you believe close to 50% is needed for that, you need
to redo your math. So no, you are wrong stating that "to exploit nothing at
stake problem you basically need to 51% attack". It is rather the opposite -
eventually, nothing at stake attack leads to ability to perform 51% attack.
>> I am not sure if this is what you call quorum-based PoS
>
> Yes, pre-selected minters is exactly what I mean by that.
>
>> it allows the attacker to know who to attack at which point with powerful
>> DDOS in order to hurt liveness of such system
>
> Just like in bitcoin, associating keys with IP addresses isn't generally an
> easy thing to do on the fly like that. If you know someone's IP address, you
> can target them. But if you only know their address or public key, the
> reverse isn't as easy. With a quorum-based PoS system, you can see their
> public key and address, but finding out their IP to DOS would be a huge
> challenge I think.
I do not dispute that the problem is not trivial, but the problem is not as
hard as you think. The network graph analysis is a known technique and it is
not trivial, but not very hard either. Introducing a large number of nodes to
the system to achieve very good success rate of analysis of area of origin of
blocks is doable and has been done in past. So again, I very much disagree with
your conclusion that this is somehow secure. It is absolutely insecure.
> Note, tho, that quorum-based PoS generally also have punishments as part of
> the protocol. The introduction of punishments do indeed handily solve the
> nothing at stake problem. And you didn't mention a single problem that the
> punishments introduce that weren't already there before punishments. There
> are tradeoffs with introducing punishments (eg in some cases you might punish
> honest actors), but they are minor in comparison to solving the nothing at
> stake problem.
While I agree that introduction of punishment itself does not imply introducing
a problem elsewhere (which I did not claim if you reread my previous message),
it does introduce additional complexity which may introduce problem, but more
importantly, while it slightly improves resistance against the nothing at stake
attack, it solves absolutely nothing. Your claim is based on wrong claim of
needed close to 50% stake, but that could not be farther from the truth. It is
not true even in optimal conditions when all participants of the network stake
or delegate their stake. These optimal conditions rarely, if ever, occur. And
that's another thing that we have not mention in our debate, so please allow me
to introduce another problem to PoS.
Consider what is needed for such optimal conditions to occur - all coins are
always part of the stake, which means that they need to somehow automatically
part of the staking process even when they are moved. But in many PoS systems
you usually require some age (in terms of confirmations) of the coin before you
allow it to be used for participation in staking process and that is for a good
reason - to prevent various grinding attacks. In some systems the coin must be
specifically registered before it can be staked, in others, simply waiting for
enough confirmations enables you to stake with the coin. I am not sure if there
is a system which does not have this cooling period for a coin that has been
moved. Maybe it is possible though, but AFAIK it is not common and not battle
tested feature.
Then if we admit that achieving the optimal condition is rather theoretical.
Then if we do not have the optimal condition, it means that a staker with K% of
the total available supply increases it's percentage over time to some amounts
>K%. As long as the staker makes sure (which is not that hard) that she does
not miss a chance to create a block, her significance in the system will always
increase in time. It will increase relative to all normal users who do not
stake (if there are any) and relative to all other stakers who make mistakes or
who are not wealthy enough to afford not selling any position ever. But
powerful attacker is exactly in such position and thus she will gain
significance in such a system. The technique I have described, and that you
mistakenly think is viable only with huge amounts of stake, only puts the
attacker to even greater advantage. But even without the described attack
(which exploits nothing at stake), the PoS system converges to a system more
and more controlled by powerful entity, which we can assume is the attacker.
> So I don't think it is at all misleading to claim that "nothing at stake" is
> a solved problem. I do in fact mean that the solutions to that problem don't
> introduce any other problems with anywhere near the same level of
> significance.
It still stands as truly misleading claim. I disagree that introducing DDOS
opportunity with medium level of difficulty for the attacker to implement it,
in case of "quorum-based PoS" is not a problem anywhere near the same level of
significance. Such an attack vector allows you to turn off the network if you
spend some time and money. That is hardly acceptable.
Just because of the above we must reject PoS as being critically insecure until
someone invents and demonstrates an actual way of solving these issues.
> On Tue, May 25, 2021 at 3:00 AM Erik Aronesty <e...@q32.com> wrote:
>
>>> > you burn them to be used at a future particular block height
>>
>>> This sounds exploitable. It seems like an attacker could simply focus all
>>> their burns on a particular set of 6 blocks to double spend, minimizing
>>> their cost of attack.
>>
>> could be right. the original idea was to have burns decay over time,
>> like ASIC's.
>>
>> anyway the point was not that "i had a magic formula"
>>
>> the point was that proof of burn is almost always better than proof of
>> stake - simply because the "proof" is on-chain, not sitting on a node
>> somewhere waiting to be stolen.
>>
>> On Mon, May 24, 2021 at 9:53 PM Billy Tetrud <billy.tet...@gmail.com> wrote:
>>>
>>> Is this the kind of proof of burn you're talking about?
>>>
>>> > if i have a choice between two chains, one longer and one shorter, i can
>>> > only choose one... deterministically
>>>
>>> What prevents you from attempting to mine block 553 on both chains?
>>>
>>> > miners have a very strong, long-term, investment in the stability of the
>>> > chain.
>>>
>>> Yes, but the same can be said of any coin, even ones that do have the
>>> nothing at stake problem. This isn't sufficient tho because the chain is a
>>> common good, and the tragedy of the commons holds for it.
>>>
>>> > you burn them to be used at a future particular block height
>>>
>>> This sounds exploitable. It seems like an attacker could simply focus all
>>> their burns on a particular set of 6 blocks to double spend, minimizing
>>> their cost of attack.
>>>
>>> > i can imagine scenarios where large stakeholders can collude to punish
>>> > smaller stakeholders simply to drive them out of business, for example
>>>
>>> Are you talking about a 51% attack? This is possible in any decentralized
>>> cryptocurrency.
>>>
>>>
>>> On Mon, May 24, 2021 at 11:49 AM Erik Aronesty <e...@q32.com> wrote:
>>>>
>>>> > > your burn investment is always "at stake", any redaction can result in
>>>> > > a loss-of-burn, because burns can be tied, precisely, to block-heights
>>>> > I'm fuzzy on how proof of burn works.
>>>>
>>>> when you burn coins, you burn them to be used at a future particular
>>>> block height: so if i'm burning for block 553, i can only use them to
>>>> mine block 553. if i have a choice between two chains, one longer
>>>> and one shorter, i can only choose one... deterministically, for that
>>>> burn: the chain with the height 553. if we fix the "lead time" for
>>>> burned coins to be weeks or even months in advance, miners have a very
>>>> strong, long-term, investment in the stability of the chain.
>>>>
>>>> therefore there is no "nothing at stake" problem. it's
>>>> deterministic, so miners have no choice. they can *only* choose the
>>>> transactions that go into the block. they cannot choose which chain
>>>> to mine, and it's time-locked, so rollbacks and instability always
>>>> hurt miners the most.
>>>>
>>>> the "punishment" systems of PoS are "weird at best", certainly
>>>> unproven. i can imagine scenarios where large stakeholders can
>>>> collude to punish smaller stakeholders simply to drive them out of
>>>> business, for example. and then you have to put checks in place to
>>>> prevent that, and more checks for those prevention system...
>>>>
>>>> in PoB, there is no complexity. simpler systems like this are
>>>> typically more secure.
>>>>
>>>> PoB also solves problems caused by "energy dependence", which could
>>>> lead to state monopolies on mining (like the new Bitcoin Mining
>>>> Council). these consortiums, if state sanctioned, could become a
>>>> source of censorship, for example. Since PoB doesn't require you to
>>>> have a live, well-connected node, it's harder to censor & harder to
>>>> trace.
>>>>
>>>> Eliminating this weakness seems to be in the best interests of
>>>> existing stakeholders
>>>>
>>>>
>>>>
>>>>
>>>> On Mon, May 24, 2021 at 4:44 PM Billy Tetrud <billy.tet...@gmail.com>
>>>> wrote:
>>>> >
>>>> > > proof of burn clearly solves this, since nothing is held online
>>>> >
>>>> > Well.. the coins to be burned need to be online when they're burned. But
>>>> > yes, only a small fraction of the total coins need to be online.
>>>> >
>>>> > > your burn investment is always "at stake", any redaction can result in
>>>> > > a loss-of-burn, because burns can be tied, precisely, to block-heights
>>>> >
>>>> > So you're saying that if say someone tries to mine a block on a shorter
>>>> > chain, that requires them to send a transaction burning their coins, and
>>>> > that transaction could also be spent on the longest chain, which means
>>>> > their coins are burned even if the chain they tried to mine on doesn't
>>>> > win? I'm fuzzy on how proof of burn works.
>>>> >
>>>> > > proof of burn can be more secure than proof-of-stake
>>>> >
>>>> > FYI, proof of stake can be done without the "nothing at stake" problem.
>>>> > You can simply punish people who mint on shorter chains (by rewarding
>>>> > people who publish proofs of this happening on the main chain). In
>>>> > quorum-based PoS, you can punish people in the quorum that propose or
>>>> > sign multiple blocks for the same height. The "nothing at stake" problem
>>>> > is a solved problem at this point for PoS.
>>>> >
>>>> >
>>>> >
>>>> > On Mon, May 24, 2021 at 3:47 AM Erik Aronesty <e...@q32.com> wrote:
>>>> >>
>>>> >> > I don't see a way to get around the conflicting requirement that the
>>>> >> > keys for large amounts of coins should be kept offline but those are
>>>> >> > exactly the coins we need online to make the scheme secure.
>>>> >>
>>>> >> proof of burn clearly solves this, since nothing is held online
>>>> >>
>>>> >> > how does proof of burn solve the "nothing at stake" problem in your
>>>> >> > view?
>>>> >>
>>>> >> definition of nothing at stake: in the event of a fork, whether the
>>>> >> fork is accidental or a malicious, the optimal strategy for any miner
>>>> >> is to mine on every chain, so that the miner gets their reward no
>>>> >> matter which fork wins. indeed in proof-of-stake, the proofs are
>>>> >> published on the very chains mines, so the incentive is magnified.
>>>> >>
>>>> >> in proof-of-burn, your burn investment is always "at stake", any
>>>> >> redaction can result in a loss-of-burn, because burns can be tied,
>>>> >> precisely, to block-heights
>>>> >>
>>>> >> as a result, miners no longer have an incentive to mine all chains
>>>> >>
>>>> >> in this way proof of burn can be more secure than proof-of-stake, and
>>>> >> even more secure than proof of work
>>>> >>
>>>> >>
>>>> >>
>>>> >>
>>>> >>
>>>> >>
>>>> >>
>>>> >> >
>>>> >>
>>>> >> On Sun, May 23, 2021 at 3:52 AM Lloyd Fournier via bitcoin-dev
>>>> >> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>> >> >
>>>> >> > Hi Billy,
>>>> >> >
>>>> >> > I was going to write a post which started by dismissing many of the
>>>> >> > weak arguments that are made against PoS made in this thread and
>>>> >> > elsewhere.
>>>> >> > Although I don't agree with all your points you have done a decent
>>>> >> > job here so I'll focus on the second part: why I think Proof-of-Stake
>>>> >> > is inappropriate for a Bitcoin-like system.
>>>> >> >
>>>> >> > Proof of stake is not fit for purpose for a global settlement layer
>>>> >> > in a pure digital asset (i.e. "digital gold") which is what Bitcoin
>>>> >> > is trying to be.
>>>> >> > PoS necessarily gives responsibilities to the holders of coins that
>>>> >> > they do not want and cannot handle.
>>>> >> > In Bitcoin, large unsophisticated coin holders can put their coins in
>>>> >> > cold storage without a second thought given to the health of the
>>>> >> > underlying ledger.
>>>> >> > As much as hardcore Bitcoiners try to convince them to run their own
>>>> >> > node, most don't, and that's perfectly acceptable.
>>>> >> > At no point do their personal decisions affect the underlying
>>>> >> > consensus -- it only affects their personal security assurance (not
>>>> >> > that of the system itself).
>>>> >> > In PoS systems this clean separation of responsibilities does not
>>>> >> > exist.
>>>> >> >
>>>> >> > I think that the more rigorously studied PoS protocols will work fine
>>>> >> > within the security claims made in their papers.
>>>> >> > People who believe that these protocols are destined for catastrophic
>>>> >> > consensus failure are certainly in for a surprise.
>>>> >> > But the devil is in the detail.
>>>> >> > Let's look at what the implications of using the leading proof of
>>>> >> > stake protocols would have on Bitcoin:
>>>> >> >
>>>> >> > ### Proof of SquareSpace (Cardano, Polkdadot)
>>>> >> >
>>>> >> > Cardano is a UTXO based PoS coin based on Ouroboros Praos[3] with an
>>>> >> > inbuilt on-chain delegation system[5].
>>>> >> > In these protocols, coin holders who do not want to run their node
>>>> >> > with their hot keys in it delegate it to a "Stake Pool".
>>>> >> > I call the resulting system Proof-of-SquareSpace since most will
>>>> >> > choose a pool by looking around for one with a nice website and
>>>> >> > offering the largest share of the block reward.
>>>> >> > On the surface this might sound no different than someone with an
>>>> >> > mining rig shopping around for a good mining pool but there are
>>>> >> > crucial differences:
>>>> >> >
>>>> >> > 1. The person making the decision is forced into it just because they
>>>> >> > own the currency -- someone with a mining rig has purchased it with
>>>> >> > the intent to make profit by participating in consensus.
>>>> >> >
>>>> >> > 2. When you join a mining pool your systems are very much still
>>>> >> > online. You are just partaking in a pool to reduce your profit
>>>> >> > variance. You still see every block that you help create and *you
>>>> >> > never help create a block without seeing it first*.
>>>> >> >
>>>> >> > 3. If by SquareSpace sybil attack you gain a dishonest majority and
>>>> >> > start censoring transactions how are the users meant to redelegate
>>>> >> > their stake to honest pools?
>>>> >> > I guess they can just send a transaction delegating to another
>>>> >> > pool...oh wait I guess that might be censored too! This seems really
>>>> >> > really bad.
>>>> >> > In Bitcoin, miners can just join a different pool at a whim. There is
>>>> >> > nothing the attacker can do to stop them. A temporary dishonest
>>>> >> > majority heals relatively well.
>>>> >> >
>>>> >> > There is another severe disadvantage to this on-chain delegation
>>>> >> > system: every UTXO must indicate which staking account this UTXO
>>>> >> > belongs to so the appropriate share of block rewards can be
>>>> >> > transferred there.
>>>> >> > Being able to associate every UTXO to an account ruins one of the
>>>> >> > main privacy advantages of the UTXO model.
>>>> >> > It also grows the size of the blockchain significantly.
>>>> >> >
>>>> >> > ### "Pure" proof of stake (Algorand)
>>>> >> >
>>>> >> > Algorand's[4] approach is to only allow online stake to participate
>>>> >> > in the protocol.
>>>> >> > Theoretically, This means that keys holding funds have to be online
>>>> >> > in order for them to author blocks when they are chosen.
>>>> >> > Of course in reality no one wants to keep their coin holding keys
>>>> >> > online so in Alogorand you can authorize a set of "participation
>>>> >> > keys"[1] that will be used to create blocks on your coin holding
>>>> >> > key's behalf.
>>>> >> > Hopefully you've spotted the problem.
>>>> >> > You can send your participation keys to any malicious party with a
>>>> >> > nice website (see random example [2]) offering you a good return.
>>>> >> > Damn it's still Proof-of-SquareSpace!
>>>> >> > The minor advantage is that at least the participation keys expire
>>>> >> > after a certain amount of time so eventually the SquareSpace attacker
>>>> >> > will lose their hold on consensus.
>>>> >> > Importantly there is also less junk on the blockchain because the
>>>> >> > participation keys are delegated off-chain and so are not making as
>>>> >> > much of a mess.
>>>> >> >
>>>> >> > ### Conclusion
>>>> >> >
>>>> >> > I don't see a way to get around the conflicting requirement that the
>>>> >> > keys for large amounts of coins should be kept offline but those are
>>>> >> > exactly the coins we need online to make the scheme secure.
>>>> >> > If we allow delegation then we open up a new social attack surface
>>>> >> > and it degenerates to Proof-of-SquareSpace.
>>>> >> >
>>>> >> > For a "digital gold" like system like Bitcoin we optimize for
>>>> >> > simplicity and desperately want to avoid extraneous responsibilities
>>>> >> > for the holder of the coin.
>>>> >> > After all, gold is an inert element on the periodic table that
>>>> >> > doesn't confer responsibilities on the holder to maintain the quality
>>>> >> > of all the other bars of gold out there.
>>>> >> > Bitcoin feels like this too and in many ways is more inert and
>>>> >> > beautifully boring than gold.
>>>> >> > For Bitcoin to succeed I think we need to keep it that way and
>>>> >> > Proof-of-Stake makes everything a bit too exciting.
>>>> >> >
>>>> >> > I suppose in the end the market will decide what is real digital gold
>>>> >> > and whether these bad technical trade offs are worth being able to
>>>> >> > say it uses less electricity. It goes without saying that making bad
>>>> >> > technical decisions to appease the current political climate is an
>>>> >> > anathema to Bitcoin.
>>>> >> >
>>>> >> > Would be interested to know if you or others think differently on
>>>> >> > these points.
>>>> >> >
>>>> >> > [1]:
>>>> >> > https://developer.algorand.org/docs/run-a-node/participate/generate_keys/
>>>> >> > [2]: https://staking.staked.us/algorand-staking
>>>> >> > [3]: https://eprint.iacr.org/2017/573.pdf
>>>> >> > [4]:
>>>> >> > https://algorandcom.cdn.prismic.io/algorandcom%2Fece77f38-75b3-44de-bc7f-805f0e53a8d9_theoretical.pdf
>>>> >> > [5]:
>>>> >> > https://hydra.iohk.io/build/790053/download/1/delegation_design_spec.pdf
>>>> >> >
>>>> >> > Cheers,
>>>> >> >
>>>> >> > LL
>>>> >> >
>>>> >> > On Fri, 21 May 2021 at 19:21, Billy Tetrud via bitcoin-dev
>>>> >> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>> >> >>
>>>> >> >> I think there is a lot of misinformation and bias against Proof of
>>>> >> >> Stake. Yes there have been lots of shady coins that use insecure PoS
>>>> >> >> mechanisms. Yes there have been massive issues with distribution of
>>>> >> >> PoS coins (of course there have also been massive issues with PoW
>>>> >> >> coins as well). However, I want to remind everyone that there is a
>>>> >> >> difference between "proved to be impossible" and "have not achieved
>>>> >> >> recognized success yet". Most of the arguments levied against PoS
>>>> >> >> are out of date or rely on unproven assumptions or extrapolation
>>>> >> >> from the analysis of a particular PoS system. I certainly don't
>>>> >> >> think we should experiment with bitcoin by switching to PoS, but
>>>> >> >> from my research, it seems very likely that there is a proof of
>>>> >> >> stake consensus protocol we could build that has substantially
>>>> >> >> higher security (cost / capital required to execute an attack) while
>>>> >> >> at the same time costing far less resources (which do translate to
>>>> >> >> fees on the network) *without* compromising any of the critical
>>>> >> >> security properties bitcoin relies on. I think the critical piece of
>>>> >> >> this is the disagreements around hardcoded checkpoints, which is a
>>>> >> >> critical piece solving attacks that could be levied on a PoS chain,
>>>> >> >> and how that does (or doesn't) affect the security model.
>>>> >> >>
>>>> >> >> @Eric Your proof of stake fallacy seems to be saying that PoS is
>>>> >> >> worse when a 51% attack happens. While I agree, I think that line of
>>>> >> >> thinking omits important facts:
>>>> >> >> * The capital required to 51% attack a PoS chain can be made
>>>> >> >> substantially greater than on a PoS chain.
>>>> >> >> * The capital the attacker stands to lose can be substantially
>>>> >> >> greater as well if the attack is successful.
>>>> >> >> * The effectiveness of paying miners to raise the honest fraction of
>>>> >> >> miners above 50% may be quite bad.
>>>> >> >> * Allowing a 51% attack is already unacceptable. It should be
>>>> >> >> considered whether what happens in the case of a 51% may not be
>>>> >> >> significantly different. The currency would likely be critically
>>>> >> >> damaged in a 51% attack regardless of consensus mechanism.
>>>> >> >>
>>>> >> >> > Proof-of-stake tends towards oligopolistic control
>>>> >> >>
>>>> >> >> People repeat this often, but the facts support this. There is no
>>>> >> >> centralization pressure in any proof of stake mechanism that I'm
>>>> >> >> aware of. IE if you have 10 times as much coin that you use to mint
>>>> >> >> blocks, you should expect to earn 10x as much minting revenue - not
>>>> >> >> more than 10x. By contrast, proof of work does in fact have clear
>>>> >> >> centralization pressure - this is not disputed. Our goal in relation
>>>> >> >> to that is to ensure that the centralization pressure remains
>>>> >> >> insignifiant. Proof of work also clearly has a lot more barriers to
>>>> >> >> entry than any proof of stake system does. Both of these mean the
>>>> >> >> tendency towards oligopolistic control is worse for PoW.
>>>> >> >>
>>>> >> >> > Energy usage, in-and-of-itself, is nothing to be ashamed of!!
>>>> >> >>
>>>> >> >> I certainly agree. Bitcoin's energy usage at the moment is I think
>>>> >> >> quite warranted. However, the question is: can we do substantially
>>>> >> >> better. I think if we can, we probably should... eventually.
>>>> >> >>
>>>> >> >> > Proof of Stake is only resilient to ⅓ of the network demonstrating
>>>> >> >> > a Byzantine Fault, whilst Proof of Work is resilient up to the ½
>>>> >> >> > threshold
>>>> >> >>
>>>> >> >> I see no mention of this in the pos.pdf you linked to. I'm not aware
>>>> >> >> of any proof that all PoS systems have a failure threshold of 1/3. I
>>>> >> >> know that staking systems like Casper do in fact have that 1/3
>>>> >> >> requirement. However there are PoS designs that should exceed that
>>>> >> >> up to nearly 50% as far as I'm aware. Proof of work is not in fact
>>>> >> >> resilient up to the 1/2 threshold in the way you would think. IE, if
>>>> >> >> 100% of miners are currently honest and have a collective 100
>>>> >> >> exahashes/s hashpower, an attacker does not need to obtain 100
>>>> >> >> exahashes/s, but actually only needs to accumulate 50 exahashes/s.
>>>> >> >> This is because as the attacker accumulates hashpower, it drives
>>>> >> >> honest miners out of the market as the difficulty increases to
>>>> >> >> beyond what is economically sustainable. Also, its been shown that
>>>> >> >> the best proof of work can do is require an attacker to obtain 33%
>>>> >> >> of the hashpower because of the selfish mining attack discussed in
>>>> >> >> depth in this paper: https://arxiv.org/abs/1311.0243. Together, both
>>>> >> >> of these things reduce PoW's security by a factor of about 83% (1 -
>>>> >> >> 50%*33%).
>>>> >> >>
>>>> >> >> > Proof of Stake requires other trade-offs which are incompatible
>>>> >> >> > with Bitcoin's objective (to be a trustless digital cash) —
>>>> >> >> > specifically the famous "security vs. liveness" guarantee
>>>> >> >>
>>>> >> >> Do you have a good source that talks about why you think proof of
>>>> >> >> stake cannot be used for a trustless digital cash?
>>>> >> >>
>>>> >> >> > You cannot gain tokens without someone choosing to give up those
>>>> >> >> > coins - a form of permission.
>>>> >> >>
>>>> >> >> This is not a practical constraint. Just like in mining, some nodes
>>>> >> >> may reject you, but there will likely be more that will accept you,
>>>> >> >> some sellers may reject you, but most would accept your money as
>>>> >> >> payment for bitcoins. I don't think requiring the "permission" of
>>>> >> >> one of millions of people in the market can be reasonably considered
>>>> >> >> a "permissioned currency".
>>>> >> >>
>>>> >> >> > 2. Proof of stake must have a trusted means of timestamping to
>>>> >> >> > regulate overproduction of blocks
>>>> >> >>
>>>> >> >> Both PoW and PoS could mine/mint blocks twice as fast if everyone
>>>> >> >> agreed to double their clock speeds. Both systems rely on an honest
>>>> >> >> majority sticking to standard time.
>>>> >> >>
>>>> >> >>
>>>> >> >> On Wed, May 19, 2021 at 5:32 AM Michael Dubrovsky via bitcoin-dev
>>>> >> >> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>> >> >>>
>>>> >> >>> Ah sorry, I didn't realize this was, in fact, a different thread! :)
>>>> >> >>>
>>>> >> >>> On Wed, May 19, 2021 at 10:07 AM Michael Dubrovsky <m...@powx.org>
>>>> >> >>> wrote:
>>>> >> >>>>
>>>> >> >>>> Folks, I suggest we keep the discussion to PoW, oPoW, and the BIP
>>>> >> >>>> itself. PoS, VDFs, and so on are interesting but I guess there are
>>>> >> >>>> other threads going on these topics already where they would be
>>>> >> >>>> relevant.
>>>> >> >>>>
>>>> >> >>>> Also, it's important to distinguish between oPoW and these other
>>>> >> >>>> "alternatives" to Hashcash. oPoW is a true Proof of Work that
>>>> >> >>>> doesn't alter the core game theory or security assumptions of
>>>> >> >>>> Hashcash and actually contains SHA (can be SHA3, SHA256, etc hash
>>>> >> >>>> is interchangeable).
>>>> >> >>>>
>>>> >> >>>> Cheers,
>>>> >> >>>> Mike
>>>> >> >>>>
>>>> >> >>>> On Tue, May 18, 2021 at 4:55 PM Erik Aronesty via bitcoin-dev
>>>> >> >>>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>>> >> >>>>>
>>>> >> >>>>> 1. i never suggested vdf's to replace pow.
>>>> >> >>>>>
>>>> >> >>>>> 2. my suggestion was specifically *in the context of* a working
>>>> >> >>>>> proof-of-burn protocol
>>>> >> >>>>>
>>>> >> >>>>> - vdfs used only for timing (not block height)
>>>> >> >>>>> - blind-burned coins of a specific age used to replace proof of
>>>> >> >>>>> work
>>>> >> >>>>> - the required "work" per block would simply be a competition to
>>>> >> >>>>> acquire rewards, and so miners would have to burn coins, well in
>>>> >> >>>>> advance, and hope that their burned coins got rewarded in some far
>>>> >> >>>>> future
>>>> >> >>>>> - the point of burned coins is to mimic, in every meaningful way,
>>>> >> >>>>> the
>>>> >> >>>>> value gained from proof of work... without some of the security
>>>> >> >>>>> drawbacks
>>>> >> >>>>> - the miner risks losing all of his burned coins (like all miners
>>>> >> >>>>> risk
>>>> >> >>>>> losing their work in each block)
>>>> >> >>>>> - new burns can't be used
>>>> >> >>>>> - old burns age out (like ASICs do)
>>>> >> >>>>> - other requirements on burns might be needed to properly mirror
>>>> >> >>>>> the
>>>> >> >>>>> properties of PoW and the incentives Bitcoin uses to mine
>>>> >> >>>>> honestly.
>>>> >> >>>>>
>>>> >> >>>>> 3. i do believe it is *possible* that a "burned coin + vdf system"
>>>> >> >>>>> might be more secure in the long run, and that if the entire space
>>>> >> >>>>> agreed that such an endeavor was worthwhile, a test net could be
>>>> >> >>>>> spun
>>>> >> >>>>> up, and a hard-fork could be initiated.
>>>> >> >>>>>
>>>> >> >>>>> 4. i would never suggest such a thing unless i believed it was
>>>> >> >>>>> possible that consensus was possible. so no, this is not an "alt
>>>> >> >>>>> coin"
>>>> >> >>>>>
>>>> >> >>>>> On Tue, May 18, 2021 at 10:02 AM Zac Greenwood
>>>> >> >>>>> <zach...@gmail.com> wrote:
>>>> >> >>>>> >
>>>> >> >>>>> > Hi ZmnSCPxj,
>>>> >> >>>>> >
>>>> >> >>>>> > Please note that I am not suggesting VDFs as a means to save
>>>> >> >>>>> > energy, but solely as a means to make the time between blocks
>>>> >> >>>>> > more constant.
>>>> >> >>>>> >
>>>> >> >>>>> > Zac
>>>> >> >>>>> >
>>>> >> >>>>> >
>>>> >> >>>>> > On Tue, 18 May 2021 at 12:42, ZmnSCPxj
>>>> >> >>>>> > <zmnsc...@protonmail.com> wrote:
>>>> >> >>>>> >>
>>>> >> >>>>> >> Good morning Zac,
>>>> >> >>>>> >>
>>>> >> >>>>> >> > VDFs might enable more constant block times, for instance by
>>>> >> >>>>> >> > having a two-step PoW:
>>>> >> >>>>> >> >
>>>> >> >>>>> >> > 1. Use a VDF that takes say 9 minutes to resolve (VDF being
>>>> >> >>>>> >> > subject to difficulty adjustments similar to the as-is). As
>>>> >> >>>>> >> > per the property of VDFs, miners are able show proof of work.
>>>> >> >>>>> >> >
>>>> >> >>>>> >> > 2. Use current PoW mechanism with lower difficulty so
>>>> >> >>>>> >> > finding a block takes 1 minute on average, again subject to
>>>> >> >>>>> >> > as-is difficulty adjustments.
>>>> >> >>>>> >> >
>>>> >> >>>>> >> > As a result, variation in block times will be greatly
>>>> >> >>>>> >> > reduced.
>>>> >> >>>>> >>
>>>> >> >>>>> >> As I understand it, another weakness of VDFs is that they are
>>>> >> >>>>> >> not inherently progress-free (their sequential nature prevents
>>>> >> >>>>> >> that; they are inherently progress-requiring).
>>>> >> >>>>> >>
>>>> >> >>>>> >> Thus, a miner which focuses on improving the amount of energy
>>>> >> >>>>> >> that it can pump into the VDF circuitry (by overclocking and
>>>> >> >>>>> >> freezing the circuitry), could potentially get into a
>>>> >> >>>>> >> winner-takes-all situation, possibly leading to even *worse*
>>>> >> >>>>> >> competition and even *more* energy consumption.
>>>> >> >>>>> >> After all, if you can start mining 0.1s faster than the
>>>> >> >>>>> >> competition, that is a 0.1s advantage where *only you* can
>>>> >> >>>>> >> mine *in the entire world*.
>>>> >> >>>>> >>
>>>> >> >>>>> >> Regards,
>>>> >> >>>>> >> ZmnSCPxj
>>>> >> >>>>> _______________________________________________
>>>> >> >>>>> bitcoin-dev mailing list
>>>> >> >>>>> bitcoin-dev@lists.linuxfoundation.org
>>>> >> >>>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>> >> >>>>
>>>> >> >>>>
>>>> >> >>>>
>>>> >> >>>> --
>>>> >> >>>> Michael Dubrovsky
>>>> >> >>>> Founder; PoWx
>>>> >> >>>> www.PoWx.org
>>>> >> >>>
>>>> >> >>>
>>>> >> >>>
>>>> >> >>> --
>>>> >> >>> Michael Dubrovsky
>>>> >> >>> Founder; PoWx
>>>> >> >>> www.PoWx.org
>>>> >> >>> _______________________________________________
>>>> >> >>> bitcoin-dev mailing list
>>>> >> >>> bitcoin-dev@lists.linuxfoundation.org
>>>> >> >>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>> >> >>
>>>> >> >> _______________________________________________
>>>> >> >> bitcoin-dev mailing list
>>>> >> >> bitcoin-dev@lists.linuxfoundation.org
>>>> >> >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>> >> >
>>>> >> > _______________________________________________
>>>> >> > bitcoin-dev mailing list
>>>> >> > bitcoin-dev@lists.linuxfoundation.org
>>>> >> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
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