path: root/73/11debce06fcf5069807841e5c9c8bc9facca98

Return-Path: <earonesty@gmail.com>
Received: from smtp4.osuosl.org (smtp4.osuosl.org [IPv6:2605:bc80:3010::137])
 by lists.linuxfoundation.org (Postfix) with ESMTP id 7D6AAC0001
 for <bitcoin-dev@lists.linuxfoundation.org>;
 Tue,  1 Jun 2021 16:33:47 +0000 (UTC)
Received: from localhost (localhost [127.0.0.1])
 by smtp4.osuosl.org (Postfix) with ESMTP id 56F67404B6
 for <bitcoin-dev@lists.linuxfoundation.org>;
 Tue,  1 Jun 2021 16:33:47 +0000 (UTC)
X-Virus-Scanned: amavisd-new at osuosl.org
X-Spam-Flag: NO
X-Spam-Score: -1.65
X-Spam-Level: 
X-Spam-Status: No, score=-1.65 tagged_above=-999 required=5
 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1,
 FREEMAIL_FORGED_FROMDOMAIN=0.001, FREEMAIL_FROM=0.001,
 HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_NONE=-0.0001,
 SPF_PASS=-0.001] autolearn=no autolearn_force=no
Authentication-Results: smtp4.osuosl.org (amavisd-new);
 dkim=pass (2048-bit key) header.d=q32-com.20150623.gappssmtp.com
Received: from smtp4.osuosl.org ([127.0.0.1])
 by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024)
 with ESMTP id cflcNYJL3c15
 for <bitcoin-dev@lists.linuxfoundation.org>;
 Tue,  1 Jun 2021 16:33:43 +0000 (UTC)
X-Greylist: whitelisted by SQLgrey-1.8.0
Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com
 [IPv6:2607:f8b0:4864:20::102c])
 by smtp4.osuosl.org (Postfix) with ESMTPS id 53225404B0
 for <bitcoin-dev@lists.linuxfoundation.org>;
 Tue,  1 Jun 2021 16:33:43 +0000 (UTC)
Received: by mail-pj1-x102c.google.com with SMTP id
 o17-20020a17090a9f91b029015cef5b3c50so1745949pjp.4
 for <bitcoin-dev@lists.linuxfoundation.org>;
 Tue, 01 Jun 2021 09:33:43 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
 d=q32-com.20150623.gappssmtp.com; s=20150623;
 h=mime-version:references:in-reply-to:from:date:message-id:subject:to
 :cc:content-transfer-encoding;
 bh=P4Ls+LyIvxvsU/wGLEpylb6AHTmXNw3hENQEI82TesA=;
 b=mZymNyf34mJo36+/fjgyreqoWyzOP9Z1dwRj9vSudCBvJ2+cpI8xiPw1a285OlbYZj
 +zLVJrK4/xZIJdAelM/5iHq5NO83Cm+IkdRcrIkg6lQpT0bW7FJJpXYZjRinAPpbq+4K
 l2Cn8BjIPXv9XQwFD1x+yyGqEIcv5M5tw8U3CNZHIhhY1GaExnThwmjjATwSavaSs0Jc
 UDJFqVbWkaFupWQT63zJFzQLeQtcB7ypnA1OLKkQRLm9TI3NA+Gt78YMnifnwFffNbCO
 NsKEtMbMz4SlOs0JtYJJITZGLyUMt0KRGeMkMFCdBA02YnzgR075UwRpnyR6wZiwEL0W
 YhzQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
 d=1e100.net; s=20161025;
 h=x-gm-message-state:mime-version:references:in-reply-to:from:date
 :message-id:subject:to:cc:content-transfer-encoding;
 bh=P4Ls+LyIvxvsU/wGLEpylb6AHTmXNw3hENQEI82TesA=;
 b=OX7ZbYYNk7u8u1tL/OZt/jBlaID4xvwfQ3Aynaq4r0Voi4fPz9ZU7JJfC1UwU1sh1q
 6gFv5689GMk5ujp3V6nzxuL/0hVe7sMjkvFkpogw3Cll8MfboSD+IEqyC8ldxjELtIl9
 qXxeNxC5bkD/40BDkh8+C6wzM4MIxe0FwXfjP7I/OHop/gB/aCXyefT/YixRarroE4RG
 YEirbShk/pgwtTDxSrK7mXY3/e+ZccZtmOO/ujBLu0JfK8PFKsPGPug/wlh61khS8iMH
 hs1CLH7NcSHQ+tiCVRd2GMbcYbpRQbG+ayvN/pvf00dGpt7Q49v+YIcMxvmJGX1tlLeo
 KlJQ==
X-Gm-Message-State: AOAM531OyRAy+AYx5jz+R77q2IAC7XTPOZ7BiBkHophMa+Innw0XD3oy
 zbw2CYwC6G/yCC9p0NZBb/uvUQ/dOO7pIhRlbtTaRjY=
X-Google-Smtp-Source: ABdhPJxyA3uYvW5nIBdmpQ8WvjYqOT6hKW1ktjOOtpayBTG0cYPBWF6PjKKk2RFTSLuCvwxeFdXAE/67SvZMh7PI3J0=
X-Received: by 2002:a17:90a:7141:: with SMTP id
 g1mr678424pjs.167.1622565221141; 
 Tue, 01 Jun 2021 09:33:41 -0700 (PDT)
MIME-Version: 1.0
References: <6do5xN2g5LPnFeM55iJ-4C4MyXOu_KeXxy68Xt4dJQMhi3LJ8ZrLICmEUlh8JGfDmsDG12m1JDAh0e0huwK_MlyKpdfn22ru3zsm7lYLfBo=@protonmail.com>
 <CAJowKgJWZ++6NkbYk15NBtA7x37of0n3_qF1UjCbV0Ui7XG8zA@mail.gmail.com>
 <CAGpPWDZs5Y10Fjbt8OPx3jEqjgNdQLODNdTW4iRyXTrpuNGFQQ@mail.gmail.com>
 <3TVoontwJmoMv0tp1S5MU_U8icxcQZfajtbNEXqOjuvO7GpfUQdh9pEGSIbLEYJndrDa_dJQqa0sSwY-BmuCmyHMRWqa9lEaUjZJSP5Vbyw=@protonmail.com>
 <CAGpPWDbqZLzMog4s9SPVm5xstbJbsHwND6x3qWHR-dh6naCnNQ@mail.gmail.com>
 <L1IhpSfDNx5OPXYnHfcFDiOzJa8jihbR8YE4MBRaYjuQt2GQsrNd0UnJaJg_mCgHNOcG6QE1Wrwp6zZ-YxOgDNu_aBE67HJkbemHz5Nz9c4=@protonmail.com>
 <CAJowKgKgGynQ9NYe_7xEai0tcBW4b=tQnNpv9vndx1hLCowfWg@mail.gmail.com>
 <J3_n3ygIuQf54KXVl8jlbyahX5WJIzffVeDD3yt0RkRbPRyD56OPj3DT05wGJoEfI6XfLOq2DiaN-vdnXSdi7Q23NWrZ-Tg9jzM9jtx8-hg=@protonmail.com>
 <CAJowKgJTEHLeHpKUOavAY9hHZ_3hChkJnMX13K-pSUhch7JwdQ@mail.gmail.com>
 <EdKK1tb2px2G--ianlCQpRjsn7vdXkSr60sV18NpVw-uVuKSA-ag9xXch_rYDkhtaJTH36zDMuVGZyYrKagMNNw_0OrLF8QsPiuo-YIxTaE=@protonmail.com>
In-Reply-To: <EdKK1tb2px2G--ianlCQpRjsn7vdXkSr60sV18NpVw-uVuKSA-ag9xXch_rYDkhtaJTH36zDMuVGZyYrKagMNNw_0OrLF8QsPiuo-YIxTaE=@protonmail.com>
From: Erik Aronesty <erik@q32.com>
Date: Tue, 1 Jun 2021 12:33:29 -0400
Message-ID: <CAJowKgK+i6WDXQcXnEEt+Y7Bq3vr64cTkSvPjraYiYhNRkBP1w@mail.gmail.com>
To: befreeandopen <befreeandopen@protonmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Mailman-Approved-At: Tue, 01 Jun 2021 18:04:40 +0000
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>,
 SatoshiSingh <SatoshiSingh@protonmail.com>,
 Billy Tetrud <billy.tetrud@gmail.com>
Subject: Re: [bitcoin-dev] Opinion on proof of stake in future
X-BeenThere: bitcoin-dev@lists.linuxfoundation.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Bitcoin Protocol Discussion <bitcoin-dev.lists.linuxfoundation.org>
List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/bitcoin-dev>, 
 <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=unsubscribe>
List-Archive: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/>
List-Post: <mailto:bitcoin-dev@lists.linuxfoundation.org>
List-Help: <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=help>
List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>, 
 <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=subscribe>
X-List-Received-Date: Tue, 01 Jun 2021 16:33:47 -0000

> Could you explain what am I missing here, because this actually does not =
seem better, but rather worse than some PoS schemes?

Given your example, if !BTC is needed to burn, that's a $50k
investment in an ASIC needed to mine a block.  That's not anywhere
near current levels.   It's not even approaching the current PoW.   A
$50k investment to be a large amount of hash power is ... well,
somewhere more than 10 years ago.

Then you compute a ratio of 200x, where someone is spending 200x the
cost needed to mine a block.   Let's use real numbers.   Look,
instead, at the global investment in ASIC's required to mine a block.
 Now assume that in PoB, miners would spend the same amount they are
today, burning coins rather than buying ASICs.

In real life, PoB is always an "equivalent defense" to PoW, because no
matter what scenario you throw at me, one can continue to tweak the
numbers until PoB *is* equivalent.

For example, If an attacker decided to amass proof-of-burn enough to
perform a reorg, they would have to essentially spend as much money as
a 51% attack today.   And they would have to do so well in advance.
We could also require a time-locked "reveal" phase where burns are
revealed to be burns well after they are incorporated - ie: it will be
public knowledge that someone is amassing a large amount of
hashpower-equivlent.   That is one of the current advantages of PoW.

My original proof-of-burn concept was designed to mimic ASICs as much
as possible:

1. large initial investment (burn to acquire power)
2. continued investment (burn to activate power in each block, lost if
block is not found)

Ideally, the attacker would have to keep burning for each lottery
ticket, which can only be used once.   Committing that burn to a
particular block for example.

Any attack you propose for a "assumed well designed PoB" can also attack Po=
W.
Any attack you propose for a "assumed well designed PoB" can also attack Po=
S.

But there are some things PoB can do that PoS can't... which is really
my original point.

- sunk costs/lost investment
- "hashpower" is "offline", and cannot be seized.






On Tue, Jun 1, 2021 at 4:21 AM befreeandopen
<befreeandopen@protonmail.com> wrote:
>
> Erik, thanks for the link. So referring to https://en.bitcoin.it/wiki/Pro=
of_of_burn, I do not really understand how this is supposed to be that much=
 better over many proof of stake proposals. If there is more research on Po=
B, please note I'm not commenting on that as I only read this wiki article =
and my comments are purely related to this only.
>
> I hope we can agree that the idea with manual insertion of entropy every =
week can be discarded, but at the same time I don't think it is a crucial p=
oint of the whole idea. So we can just focus on the rest of it.
>
> Then the whole idea seems just like certain proof of stake implementation=
s with just small differences, which I try to summarize:
>
> - in PoB, in order to use the coin for block production, you burn it in t=
he past and wait some time -- in the certain PoS I'm talking about, in orde=
r to use the coin, you do not move the coin for some time - so in both ther=
e is the same idea - you somehow make the coin eligible for the block creat=
ion process by first doing some action followed by some inaction for some t=
ime; the difference here is that if later you use such coin in PoS, then af=
ter waiting more time, you can use the coin again (for whatever purpose), w=
hile in PoB the coin is gone forever (it is burned); this does not seem to =
be fundamentally different
>
> - in PoB, the author suggests there is an exponential decay of the power =
of the coin to create a block; in some PoS schemas, there historically was =
an era of so called CoinAge mechanism, which was somewhat inverse to this e=
xponential decay, it was that the coin gets more power the older it is unto=
uched, some implementations were for linear increase in the power, some exp=
onential. Usually there was a certain limit - i.e. a maximum power the coin=
 may have reached. It turned out quite quickly that such property is making=
 attacks easier. PoB reverses the idea, but I don't think that helps that m=
uch. In any case, there seems to be an optimal period of time for each used=
 coin, in both PoS and PoB, where the coin is most suitable for block produ=
ction. I admit PoB version is better, but the crucial property here is that=
 some coins are more powerful than other.
>
> - in both PoB and PoS it seems there is linear increase of the ability of=
 the coin to produce blocks with the size of the coin (more BTC you burn/st=
ake, the better your chance)
>
> This characteristic of PoB does not suggest that it would have that much =
different properties than PoS. So it should suffer from same problems as Po=
S. Namely, the problems I see now, with the given proposal from wiki, are:
>
> - there seems to be lack of definition of the heaviest chain and difficul=
ty adjustment - this seems crucial, but likely solvable, I'm just saying it=
 is importantly missing in the description
>
> - there seems to be a problem with nothing at stake (nothing at burn mayb=
e?) - How that can be? Again, it seems that every burned coin can be used f=
or free checks at any time after the initial waiting period. These free che=
cks are indeed free and are the core of the nothing at stake problem in PoS=
. You seem to make those checks for free and you seem to be able to use tho=
se burned coins to create arbitrary number of forks build on any parent blo=
cks of your choice, not just the last block of the heaviest chain. I can't =
see at the moment how is this different from PoS nothing at stake problem. =
Maybe you can explain?
>
> - it seems to me that there is a trivial attack against the scheme by a w=
ealthy attacker. Suppose a common size of the burn is 1 BTC per block, supp=
ose you define the heaviest chain rule somehow in relation to total number =
of burned coins or the cumulative "strength" of the "lowest" hashes, then y=
ou can just burn 20 UTXOs, each being 10 BTC in value, so you spent 200 BTC=
 on this attack, but you are in very strong position because after you wait=
 the needed time, you should be able to do pretty nasty reorg. Suppose that=
 the main chain is A-B-C-D-E-F, so what you do at that point is that you ju=
st "try for free" all your 20 UTXOs, whether or not they can build on top o=
f block A (which has 5 confs on top, F is the tip of the main chain). Since=
 you have big UTXOs, your chances should be good, of course you can always =
try many times because you have a "lottery ticket" for every timestampt t. =
So with this you should be able, with good chance, to find such B' and then=
 you have 19 UTXOs remaining to try to build on B' in the same way. I can't=
 see what prevents this attack in the described scheme.
>
> - the ability to retroactively try all different kids of timestamp t seem=
s devastating - you again get super easy and somewhat cheap attack (due to =
nothing at burn problem) that allows you to rewrite even long chains at wil=
l.
>
>
> Could you explain what am I missing here, because this actually does not =
seem better, but rather worse than some PoS schemes?
>
>
>
>
> Sent with ProtonMail Secure Email.
>
> =E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90 Original =
Message =E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90
> On Friday, May 28, 2021 9:06 PM, Erik Aronesty <erik@q32.com> wrote:
>
> > best writeup i know of is here:
> >
> > https://en.bitcoin.it/wiki/Proof_of_burn
> >
> > no formal proposals or proofs that i know of.
> >
> > On Fri, May 28, 2021 at 10:40 AM befreeandopen
> > befreeandopen@protonmail.com wrote:
> >
> > > Erik, I am sorry, I have little knowledge about proof-of-burn, I neve=
r found it interesting up until now. Some of your recent claims seem quite =
strong to me and I'd like to read more.
> > > Forgive me if this has been mentioned recently, but is there a full s=
pecification of the concept you are referring to? I don't mean just the bas=
ic idea description (that much is clear to me), I mean a fully detailed pro=
posal or technical documentation that would give me a precise information a=
bout what exactly it is that you are talking about.
> > > Sent with ProtonMail Secure Email.
> > > =E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90 Origi=
nal Message =E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90=E2=80=90
> > > On Wednesday, May 26, 2021 11:07 PM, Erik Aronesty erik@q32.com wrote=
:
> > >
> > > > note: the "nothing at stake" problem you propose is not broken for
> > > > proof-of-burn, because the attacker
> > > > a) has no idea which past transactions are burns
> > > > b) has no way to use his mining power, even 5%, to maliciously impr=
ove
> > > > his odds of being selected
> > > > On Wed, May 26, 2021 at 9:12 AM befreeandopen
> > > > befreeandopen@protonmail.com wrote:
> > > >
> > > > > @befreeandopen I guess I misunderstood your selfish minting attac=
k. Let me make sure I understand it. You're saying it would go as follows?:
> > > > >
> > > > > 1.  The malicious actor comes across an opportunity to mint the n=
ext 3 blocks. But they hold off and don't release their blocks just yet.
> > > > > 2.  They receive a new block minted by someone else.
> > > > > 3.  The malicious actor then chooses to release their other 2 blo=
cks on on the second from the top block if it gives them more blocks in the=
 future than minting on the top block. And instead lets the top block proce=
ed if it gives them more blocks in the future (also figuring in the 3 block=
s they're missing out on minting).
> > > > > 4.  Profit!
> > > > >
> > > > > The problem with this attack is that any self respecting PoS syst=
em wouldn't have the information available for minters to know how blocks w=
ill affect their future prospects of minting. Otherwise this would introduc=
e the problem of stake grinding. This can be done using collaborative rando=
mness (where numbers from many parties are combined to create a random numb=
er that no individual party could predict). In fact, that's what the Casper=
 protocol does to decide quorums. In a non quorum case, you can do somethin=
g like record a hash of a number in the block header, and then have a secon=
d step to release that number later. Rewards can be given can be used to en=
sure minters act honestly here by minting messages that release these numbe=
rs and not releasing their secret numbers too early.
> > > > > Yes, you misunderstood it. First, let me say that the above thoug=
hts of yours are incorrect, at least for non-quorum case. Since the transit=
ion in the blockchain system from S1 to S2 is only by adding new block, and=
 since stakers always need to be able to decide whether or not they can add=
 the next block, it follows that if a staker creates a new block locally, s=
he can decide whether the new state allows her to add another block on top.=
 As you mentioned, this COULD introduce problem of staking, that you are in=
correct in that it is a necessity. Usual prevention of the grinding problem=
 in this case is that an "old enough" source of randomness applies for the =
current block production process. Of course this, as it is typical for PoS,=
 introduces other problems, but let's discard those.
> > > > > I will try to explain in detail what you misunderstood before. Yo=
u start with a chain ending with blocks A-B-C, C being the top, the common =
feature of PoS system (non-quorum), roughly speaking, is that if N is the t=
otal amount of coins that participate in the staking process to create a ne=
w block on top of C (let's call that D), then a participant having K*N amou=
nt of stake has chance K to be the one who will create the next stake. In o=
ther words, the power of stakers is supposed to be linear in the system - y=
ou own 10 coins gives you 10x the chance of finding block over someone who =
has 1 coin.
> > > > > What i was claiming is that using the technique I have described,=
 this linearity is violated. Why? Well, it works for honest stakers among t=
he competition of honest stakers - they really do have the chance of K to f=
ind the next block. However, the attacker, using nothing at stake, checks h=
er ability to build block D (at some timestamp). If she is successful, she =
does not propagate D immediately, but instead she also checks whether she c=
an build on top of B and on top of A. Since with every new timestamp, usual=
ly, there is a new chance to build the block, it is not uncommon that she f=
inds she is indeed able to build such block C' on top of B. Here it is like=
ly t(C') > t(C) as the attacker has relatively low stake. Note that in orde=
r to produce such C', she not only could have tried the current timestamp t=
(D), but also all previous timestamps up to t(B) (usually that's the consen=
sus rule, but it may depend on a specific consensus). So her chance to prod=
uce such C' is greater than her previous chance of producing C (which chanc=
e was limited by other stakers in the system and the discovery of block C b=
y one of them). Now suppose that she found such C' and now she continues by=
 trying to prolong this chain by finding D'. And again here, it is quite li=
kely that her chance to find such D' is greater than was her chance of find=
ing D because again there are likely multiple timestamps she could try. Thi=
s all was possible just because nothing at stake allows you to just try if =
you can produce a block in certain state of block chain or not. Now if she =
actually was able to find D', she discards D and only publishes chain A-B-C=
'-D', which can not be punished despite the fact that she indeed produced t=
wo different forks. She can not be punished because this production was loc=
al and only the final result of A-B-C'-D' was published, in which case she =
gained an extra block over the honest strategy which would only give her bl=
ock D.
> > > > > Fun fact tho: there is an attack called the "selfish mining attac=
k" for proof of work, and it reduces the security of PoW by at least 1/3rd.
> > > > > How is that relevant to our discussion? This is known research th=
at has nothing to do with PoS except that it is often worse on PoS.
> > > > >
> > > > > > the problem is not as hard as you think
> > > > >
> > > > > I don't claim to know just how hard finding the IP address associ=
ated with a bitcoin address is. However, the DOS risk can be solved more co=
mpletely by only allowing the owner of coins themselves to know whether the=
y can mint a block. Eg by determining whether someone can mint a block base=
d on their public key hidden behind hashes (as normal in addresses). Only w=
hen someone does in fact mint a block do they reveal their hidden public ke=
y in order to prove they are allowed to mint the block.
> > > > > This is true, but you are mixing quorum and non-quorum systems. M=
y objection here was towards such system where I specifically said that the=
 list of producers for next epoch is known up front and you confirmed that =
this is what you meant with "quorum" system. So in such system, I claimed, =
the known producer is the only target at any given point of time. This of c=
ourse does not apply to any other type of system where future producers are=
 not known. No need to dispute, again, something that was not claimed.
> > > > >
> > > > > > I agree that introduction of punishment itself does not imply i=
ntroducing a problem elsewhere (which I did not claim if you reread my prev=
ious message)
> > > > >
> > > > > I'm glad we agree there. Perhaps I misunderstood what you meant b=
y "you should not omit to mention that by doing so, typically, you have int=
roduced another problem elsewhere."
> > > > > Perhaps you should quote the full sentence and not just a part of=
 it:
> > > > > "Of course you can always change the rules in a way that a certai=
n specific attack is not doable, but you should not omit to mention that by=
 doing so, typically, you have introduced another problem elsewhere, or you=
 have not solved it completely."
> > > > > You can parse this as: (CREATE PROBLEM ELSEWHERE) OR (NOT SOLVE I=
T COMPLETELY)
> > > > > In case of the punishment it was meant to be the not solve it com=
pletely part.
> > > > > Also "typically" does not imply always.
> > > > > But this parsing of English sentences for you seems very off topi=
c here. My point is, in context of Bitcoin, reject such unsupported claims =
that PoS is a reasonable alternative to PoW, let's stick to that.
> > > > >
> > > > > > 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 syste=
m will always increase in time. It will increase relative to all normal use=
rs who do not stake
> > > > >
> > > > > Well, if you're in the closed system of the cryptocurrency, sure.=
 But we don't live in that closed system. Minters will earn some ROI from m=
inting just like any other financial activity. Others may find more success=
 spending their time doing things other than figuring out how to mint coins=
. In that case, they'll be able to earn more coin that they could later dec=
ide to use to mint blocks if they decide to.
> > > > > This only supports the point I was making. Since the optimal scen=
ario with all existing coins participating is just theoretical, the attacke=
r's position will ever so improve. It seems we are in agreement here, great=
.
> > > > >
> > > > > > Just because of the above we must reject PoS as being criticall=
y insecure
> > > > >
> > > > > I think the only thing we can conclude from this is that you have=
 come up with an insecure proof of stake protocol. I don't see how anything=
 you've brought up amounts to substantial evidence that all possible PoS pr=
otocols are insecure.
> > > > > I have not come up with anything. I'm afraid you've not realized =
the burden of proof is on your side if you vouch for a design that is not b=
elieved and trusted to be secure. It is up to you to show that you know how=
 to solve every problem that people throw at you. So far we have just demon=
strated that your claim that nothing at stake is solved was unjustified. Yo=
u have not described a system that would solve it (and not introduce critic=
al DDOS attack vector as it is in quorum based systems - per the prior defi=
nition of such systems).
> > > > > Of course the list of problems of PoS systems do not end with jus=
t nothing at stake, but it is good enough example that by itself prevents i=
ts adoption in decentralized consensus. No need to go to other hard problem=
s without solving nothing at stake.
> > > > > On Tue, May 25, 2021 at 11:10 AM befreeandopen befreeandopen@prot=
onmail.com wrote:
> > > > >
> > > > > > @befreeandopen " An attacker can calculate whether or not she c=
an 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 q=
uite close to 50%. At that point, you're talking about a 51% attack, not th=
e nothing at stake problem. The nothing at stake problem is the problem whe=
re anyone will mint on any chain. Its clear that if there's a substantial p=
unishment for minting on chains other than the one that eventually wins, ev=
ery minter without a significant fraction of the stake will be honest and n=
ot 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 att=
acker would need probably >45% of the active stake (take a look at the reas=
oning here for a deeper analysis of that statement), I don't agree that pun=
ishment 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 c=
ourse 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 de=
scribed 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 t=
o completely take control the network (in short term), but rather that the =
attacker has significant advantage in the number of blocks she creates comp=
ared to what she "should be able to create". This means the attacker's stak=
e increases significantly faster than of the honest nodes, which in long te=
rm 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 ex=
ploit nothing at stake problem you basically need to 51% attack". It is rat=
her 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 w=
ith 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 I=
P address, you can target them. But if you only know their address or publi=
c key, the reverse isn't as easy. With a quorum-based PoS system, you can s=
ee 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 probl=
em is not as hard as you think. The network graph analysis is a known techn=
ique and it is not trivial, but not very hard either. Introducing a large n=
umber 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 i=
s absolutely insecure.
> > > > > > Note, tho, that quorum-based PoS generally also have punishment=
s as part of the protocol. The introduction of punishments do indeed handil=
y solve the nothing at stake problem. And you didn't mention a single probl=
em that the punishments introduce that weren't already there before punishm=
ents. There are tradeoffs with introducing punishments (eg in some cases yo=
u 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 i=
mply introducing a problem elsewhere (which I did not claim if you reread m=
y previous message), it does introduce additional complexity which may intr=
oduce problem, but more importantly, while it slightly improves resistance =
against the nothing at stake attack, it solves absolutely nothing. Your cla=
im 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 optima=
l 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 someh=
ow 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 p=
rocess 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 s=
take 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 th=
ough, 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 ove=
r 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 significa=
nce in the system will always increase in time. It will increase relative t=
o 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 positi=
on and thus she will gain significance in such a system. The technique I ha=
ve described, and that you mistakenly think is viable only with huge amount=
s of stake, only puts the attacker to even greater advantage. But even with=
out 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 tha=
t problem don't introduce any other problems with anywhere near the same le=
vel of significance.
> > > > > > It still stands as truly misleading claim. I disagree that intr=
oducing DDOS opportunity with medium level of difficulty for the attacker t=
o implement it, in case of "quorum-based PoS" is not a problem anywhere nea=
r 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 criticall=
y insecure until someone invents and demonstrates an actual way of solving =
these issues.
> > > > > > On Tue, May 25, 2021 at 3:00 AM Erik Aronesty erik@q32.com wrot=
e:
> > > > > >
> > > > > > > > > you burn them to be used at a future particular block hei=
ght
> > > > > > >
> > > > > > > > This sounds exploitable. It seems like an attacker could si=
mply 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 ove=
r 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 o=
n a node
> > > > > > > somewhere waiting to be stolen.
> > > > > > > On Mon, May 24, 2021 at 9:53 PM Billy Tetrud billy.tetrud@gma=
il.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 s=
tability of the chain.
> > > > > > > >
> > > > > > > > Yes, but the same can be said of any coin, even ones that d=
o 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 hei=
ght
> > > > > > > >
> > > > > > > > This sounds exploitable. It seems like an attacker could si=
mply 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 coll=
ude to punish smaller stakeholders simply to drive them out of business, fo=
r 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 erik@q32.com=
 wrote:
> > > > > > > >
> > > > > > > > > > > your burn investment is always "at stake", any redact=
ion 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, on=
e longer
> > > > > > > > > and one shorter, i can only choose one... deterministical=
ly, 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, miner=
s have a very
> > > > > > > > > strong, long-term, investment in the stability of the cha=
in.
> > > > > > > > > therefore there is no "nothing at stake" problem. it's
> > > > > > > > > deterministic, so miners have no choice. they can only ch=
oose the
> > > > > > > > > transactions that go into the block. they cannot choose w=
hich chain
> > > > > > > > > to mine, and it's time-locked, so rollbacks and instabili=
ty always
> > > > > > > > > hurt miners the most.
> > > > > > > > > the "punishment" systems of PoS are "weird at best", cert=
ainly
> > > > > > > > > unproven. i can imagine scenarios where large stakeholder=
s can
> > > > > > > > > collude to punish smaller stakeholders simply to drive th=
em 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", w=
hich could
> > > > > > > > > lead to state monopolies on mining (like the new Bitcoin =
Mining
> > > > > > > > > Council). these consortiums, if state sanctioned, could b=
ecome a
> > > > > > > > > source of censorship, for example. Since PoB doesn't requ=
ire 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 interes=
ts of
> > > > > > > > > existing stakeholders
> > > > > > > > > On Mon, May 24, 2021 at 4:44 PM Billy Tetrud billy.tetrud=
@gmail.com wrote:
> > > > > > > > >
> > > > > > > > > > > proof of burn clearly solves this, since nothing is h=
eld online
> > > > > > > > > >
> > > > > > > > > > Well.. the coins to be burned need to be online when th=
ey're burned. But yes, only a small fraction of the total coins need to be =
online.
> > > > > > > > > >
> > > > > > > > > > > your burn investment is always "at stake", any redact=
ion 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 bl=
ock on a shorter chain, that requires them to send a transaction burning th=
eir coins, and that transaction could also be spent on the longest chain, w=
hich means their coins are burned even if the chain they tried to mine on d=
oesn'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 (b=
y 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 s=
ign 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 erik@q32.=
com wrote:
> > > > > > > > > >
> > > > > > > > > > > > I don't see a way to get around the conflicting req=
uirement that the keys for large amounts of coins should be kept offline bu=
t those are exactly the coins we need online to make the scheme secure.
> > > > > > > > > > >
> > > > > > > > > > > proof of burn clearly solves this, since nothing is h=
eld 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 for=
k, whether the
> > > > > > > > > > > fork is accidental or a malicious, the optimal strate=
gy for any miner
> > > > > > > > > > > is to mine on every chain, so that the miner gets the=
ir 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 mi=
ne all chains
> > > > > > > > > > > in this way proof of burn can be more secure than pro=
of-of-stake, and
> > > > > > > > > > > even more secure than proof of work
> > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > On Sun, May 23, 2021 at 3:52 AM Lloyd Fournier via bi=
tcoin-dev
> > > > > > > > > > > bitcoin-dev@lists.linuxfoundation.org wrote:
> > > > > > > > > > >
> > > > > > > > > > > > Hi Billy,
> > > > > > > > > > > > I was going to write a post which started by dismis=
sing many of the weak arguments that are made against PoS made in this thre=
ad and elsewhere.
> > > > > > > > > > > > Although I don't agree with all your points you hav=
e done a decent job here so I'll focus on the second part: why I think Proo=
f-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 wha=
t Bitcoin is trying to be.
> > > > > > > > > > > > PoS necessarily gives responsibilities to the holde=
rs 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 healt=
h 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 responsibil=
ities does not exist.
> > > > > > > > > > > > I think that the more rigorously studied PoS protoc=
ols will work fine within the security claims made in their papers.
> > > > > > > > > > > > People who believe that these protocols are destine=
d 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 le=
ading proof of stake protocols would have on Bitcoin:
> > > > > > > > > > > >
> > > > > > > > > > > > ### Proof of SquareSpace (Cardano, Polkdadot)
> > > > > > > > > > > >
> > > > > > > > > > > > Cardano is a UTXO based PoS coin based on Ouroboros=
 Praos3 with an inbuilt on-chain delegation system5.
> > > > > > > > > > > > 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 si=
nce most will choose a pool by looking around for one with a nice website a=
nd offering the largest share of the block reward.
> > > > > > > > > > > > On the surface this might sound no different than s=
omeone 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 i=
t just because they own the currency -- someone with a mining rig has purch=
ased it with the intent to make profit by participating in consensus.
> > > > > > > > > > > >
> > > > > > > > > > > > 2.  When you join a mining pool your systems are ve=
ry much still online. You are just partaking in a pool to reduce your profi=
t variance. You still see every block that you help create and you never he=
lp create a block without seeing it first.
> > > > > > > > > > > >
> > > > > > > > > > > > 3.  If by SquareSpace sybil attack you gain a disho=
nest majority and start censoring transactions how are the users meant to r=
edelegate their stake to honest pools?
> > > > > > > > > > > >     I guess they can just send a transaction delega=
ting to another pool...oh wait I guess that might be censored too! This see=
ms really really bad.
> > > > > > > > > > > >     In Bitcoin, miners can just join a different po=
ol at a whim. There is nothing the attacker can do to stop them. A temporar=
y dishonest majority heals relatively well.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > There is another severe disadvantage to this on-cha=
in delegation system: every UTXO must indicate which staking account this U=
TXO belongs to so the appropriate share of block rewards can be transferred=
 there.
> > > > > > > > > > > > Being able to associate every UTXO to an account ru=
ins one of the main privacy advantages of the UTXO model.
> > > > > > > > > > > > It also grows the size of the blockchain significan=
tly.
> > > > > > > > > > > >
> > > > > > > > > > > > ### "Pure" proof of stake (Algorand)
> > > > > > > > > > > >
> > > > > > > > > > > > Algorand's4 approach is to only allow online stake =
to participate in the protocol.
> > > > > > > > > > > > Theoretically, This means that keys holding funds h=
ave to be online in order for them to author blocks when they are chosen.
> > > > > > > > > > > > Of course in reality no one wants to keep their coi=
n holding keys online so in Alogorand you can authorize a set of "participa=
tion keys"1 that will be used to create blocks on your coin holding key's b=
ehalf.
> > > > > > > > > > > > Hopefully you've spotted the problem.
> > > > > > > > > > > > You can send your participation keys to any malicio=
us party with a nice website (see random example 2) offering you a good ret=
urn.
> > > > > > > > > > > > Damn it's still Proof-of-SquareSpace!
> > > > > > > > > > > > The minor advantage is that at least the participat=
ion keys expire after a certain amount of time so eventually the SquareSpac=
e attacker will lose their hold on consensus.
> > > > > > > > > > > > Importantly there is also less junk on the blockcha=
in because the participation keys are delegated off-chain and so are not ma=
king as much of a mess.
> > > > > > > > > > > >
> > > > > > > > > > > > ### Conclusion
> > > > > > > > > > > >
> > > > > > > > > > > > I don't see a way to get around the conflicting req=
uirement that the keys for large amounts of coins should be kept offline bu=
t 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 op=
timize for simplicity and desperately want to avoid extraneous responsibili=
ties 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 q=
uality of all the other bars of gold out there.
> > > > > > > > > > > > Bitcoin feels like this too and in many ways is mor=
e inert and beautifully boring than gold.
> > > > > > > > > > > > For Bitcoin to succeed I think we need to keep it t=
hat 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 bei=
ng able to say it uses less electricity. It goes without saying that making=
 bad technical decisions to appease the current political climate is an ana=
thema to Bitcoin.
> > > > > > > > > > > > Would be interested to know if you or others think =
differently on these points.
> > > > > > > > > > > > Cheers,
> > > > > > > > > > > > LL
> > > > > > > > > > > > On Fri, 21 May 2021 at 19:21, Billy Tetrud via bitc=
oin-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 i=
nsecure PoS mechanisms. Yes there have been massive issues with distributio=
n of PoS coins (of course there have also been massive issues with PoW coin=
s as well). However, I want to remind everyone that there is a difference b=
etween "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 u=
nproven assumptions or extrapolation from the analysis of a particular PoS =
system. I certainly don't think we should experiment with bitcoin by switch=
ing to PoS, but from my research, it seems very likely that there is a proo=
f of stake consensus protocol we could build that has substantially higher =
security (cost / capital required to execute an attack) while at the same t=
ime 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 hardcod=
ed checkpoints, which is a critical piece solving attacks that could be lev=
ied on a PoS chain, and how that does (or doesn't) affect the security mode=
l.
> > > > > > > > > > > > > @Eric Your proof of stake fallacy seems to be say=
ing that PoS is worse when a 51% attack happens. While I agree, I think tha=
t line of thinking omits important facts:
> > > > > > > > > > > > >
> > > > > > > > > > > > > -   The capital required to 51% attack a PoS chai=
n can be made substantially greater than on a PoS chain.
> > > > > > > > > > > > > -   The capital the attacker stands to lose can b=
e substantially greater as well if the attack is successful.
> > > > > > > > > > > > > -   The effectiveness of paying miners to raise t=
he 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 damage=
d in a 51% attack regardless of consensus mechanism.
> > > > > > > > > > > > >
> > > > > > > > > > > > > > Proof-of-stake tends towards oligopolistic cont=
rol
> > > > > > > > > > > > >
> > > > > > > > > > > > > People repeat this often, but the facts support t=
his. There is no centralization pressure in any proof of stake mechanism th=
at 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 th=
an 10x. By contrast, proof of work does in fact have clear centralization p=
ressure - this is not disputed. Our goal in relation to that is to ensure t=
hat the centralization pressure remains insignifiant. Proof of work also cl=
early 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 b=
e ashamed of!!
> > > > > > > > > > > > >
> > > > > > > > > > > > > I certainly agree. Bitcoin's energy usage at the =
moment is I think quite warranted. However, the question is: can we do subs=
tantially better. I think if we can, we probably should... eventually.
> > > > > > > > > > > > >
> > > > > > > > > > > > > > Proof of Stake is only resilient to =E2=85=93 o=
f the network demonstrating a Byzantine Fault, whilst Proof of Work is resi=
lient up to the =C2=BD threshold
> > > > > > > > > > > > >
> > > > > > > > > > > > > I see no mention of this in the pos.pdf you linke=
d to. I'm not aware of any proof that all PoS systems have a failure thresh=
old 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 t=
o the 1/2 threshold in the way you would think. IE, if 100% of miners are c=
urrently honest and have a collective 100 exahashes/s hashpower, an attacke=
r does not need to obtain 100 exahashes/s, but actually only needs to accum=
ulate 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: htt=
ps://arxiv.org/abs/1311.0243. Together, both of these things reduce PoW's s=
ecurity 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) =
=E2=80=94 specifically the famous "security vs. liveness" guarantee
> > > > > > > > > > > > >
> > > > > > > > > > > > > Do you have a good source that talks about why yo=
u 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 a=
s payment for bitcoins. I don't think requiring the "permission" of one of =
millions of people in the market can be reasonably considered a "permission=
ed 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 Dubrov=
sky mike@powx.org wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Folks, I suggest we keep the discussion to Po=
W, oPoW, and the BIP itself. PoS, VDFs, and so on are interesting but I gue=
ss there are other threads going on these topics already where they would b=
e relevant.
> > > > > > > > > > > > > > > Also, it's important to distinguish between o=
PoW and these other "alternatives" to Hashcash. oPoW is a true Proof of Wor=
k that doesn't alter the core game theory or security assumptions of Hashca=
sh and actually contains SHA (can be SHA3, SHA256, etc hash is interchangea=
ble).
> > > > > > > > > > > > > > > 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 c=
ontext of a working
> > > > > > > > > > > > > > > >     proof-of-burn protocol
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > -   vdfs used only for timing (not block he=
ight)
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > -   blind-burned coins of a specific age us=
ed to replace proof of work
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > -   the required "work" per block would sim=
ply be a competition to
> > > > > > > > > > > > > > > >     acquire rewards, and so miners would ha=
ve to burn coins, well in
> > > > > > > > > > > > > > > >     advance, and hope that their burned coi=
ns 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... with=
out some of the security
> > > > > > > > > > > > > > > >     drawbacks
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > -   the miner risks losing all of his burne=
d 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 ne=
eded to properly mirror the
> > > > > > > > > > > > > > > >     properties of PoW and the incentives Bi=
tcoin uses to mine honestly.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > 3.  i do believe it is possible that a "bur=
ned coin + vdf system"
> > > > > > > > > > > > > > > >     might be more secure in the long run, a=
nd that if the entire space
> > > > > > > > > > > > > > > >     agreed that such an endeavor was worthw=
hile, a test net could be spun
> > > > > > > > > > > > > > > >     up, and a hard-fork could be initiated.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > 4.  i would never suggest such a thing unle=
ss i believed it was
> > > > > > > > > > > > > > > >     possible that consensus was possible. s=
o no, this is not an "alt
> > > > > > > > > > > > > > > >     coin"
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > On Tue, May 18, 2021 at 10:02 AM Zac Greenw=
ood zachgrw@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 Zm=
nSCPxj@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 minute=
s 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 lo=
wer 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 natur=
e prevents that; they are inherently progress-requiring).
> > > > > > > > > > > > > > > > > > Thus, a miner which focuses on improvin=
g the amount of energy that it can pump into the VDF circuitry (by overcloc=
king and freezing the circuitry), could potentially get into a winner-takes=
-all situation, possibly leading to even worse competition and even more en=
ergy consumption.
> > > > > > > > > > > > > > > > > > After all, if you can start mining 0.1s=
 faster than the competition, that is a 0.1s advantage where only you can m=
ine in the entire world.
> > > > > > > > > > > > > > > > > > Regards,
> > > > > > > > > > > > > > > > > > ZmnSCPxj
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > bitcoin-dev mailing list
> > > > > > > > > > > > > > > > bitcoin-dev@lists.linuxfoundation.org
> > > > > > > > > > > > > > > > https://lists.linuxfoundation.org/mailman/l=
istinfo/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/listi=
nfo/bitcoin-dev
> > > > > > > > > > > > >
> > > > > > > > > > > > > bitcoin-dev mailing list
> > > > > > > > > > > > > bitcoin-dev@lists.linuxfoundation.org
> > > > > > > > > > > > > https://lists.linuxfoundation.org/mailman/listinf=
o/bitcoin-dev
> > > > > > > > > > > >
> > > > > > > > > > > > bitcoin-dev mailing list
> > > > > > > > > > > > bitcoin-dev@lists.linuxfoundation.org
> > > > > > > > > > > > https://lists.linuxfoundation.org/mailman/listinfo/=
bitcoin-dev
>
>