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MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_22218_1777691746.1761608660135" X-Original-Sender: mtidwell021@gmail.com Precedence: list Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com List-ID: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -0.5 (/) ------=_Part_22218_1777691746.1761608660135 Content-Type: multipart/alternative; boundary="----=_Part_22219_1533187384.1761608660135" ------=_Part_22219_1533187384.1761608660135 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable > MRH tracking might make that acceptable, but comes at a high cost which I= =20 think would clearly not be justified. Greg, I want to ask/challenge how bad this is, this seems like a generally= =20 reusable primitive that could make other upgrades more feasible that also= =20 have the same strict confiscation risk profile. IIUC, the major pain is, 1 big reindex cost + a few bytes per utxo? Poelstra, > I don't think this is a great idea -- it would be technically hard to implement and slow deployment indefinitely. I would like to know how much of a deal breaker this is in your opinion. Is= =20 MRH tracking off the table? In terms of the hypothetical presigned=20 transactions that may exist using P2MS, is this a hard enough reason to=20 require a MRH idea? Greg, > So, paradoxically this limit might increase the amount of non-prunable=20 data I believe you're pointing out the idea of non economically-rational=20 spammers? We already see actors ignoring cheaper witness inscription=20 methods. If spam shifts to many sub-520 fake pubkey outputs (which I=20 believe is less harmful than stamps), that imo is a separate UTXO cost=20 discussion. (like a SF to add weight to outputs). Anywho, this point alone= =20 doesn't seem sufficient to add as a clear negative reason for someone=20 opposed to the proposal. Thanks, Tidwell On Wednesday, October 22, 2025 at 5:55:58=E2=80=AFAM UTC-4 moonsettler wrot= e: > > Confiscation is a problem because of presigned transactions > > Allow 10000 bytes of total scriptPubKey size in each block counting only= =20 > those outputs that are larger than x (520 as proposed). > The code change is pretty minimal from the most obvious implementation of= =20 > the original rule. > > That makes it technically non-confiscatory. Still non-standard, but if=20 > anyone out there so obnoxiously foot-gunned themselves, they can't claim= =20 > they were rugged by the devs. > > BR, > moonsettler > > On Saturday, October 18th, 2025 at 3:15 PM, PortlandHODL =20 > wrote: > > > Hey, > >=20 > > First, thank you to everyone who responded, and please continue to do= =20 > so. There were many thought provoking responses and this did shift my=20 > perspective quite a bit from the original post, which in of itself was th= e=20 > goal to a degree. > >=20 > > I am currently only going to respond to all of the current concerns.=20 > Acks; though I like them will be ignored unless new discoveries are=20 > included. > >=20 > > Tl;dr (Portlands Perspective) > > - Confiscation is a problem because of presigned transactions > > - DoS mitigation could also occur through marking UTXOs as unspendable= =20 > if > 520 bytes, this would preserve the proof of publication. > > - Timeout / Sunset logic is compelling > > - The (n) value of acceptable needed bytes is contentious with the lowe= r=20 > suggested limit being 67 > > - Congestion control is worth a look? > >=20 > > Next Step: > > - Deeper discussion at the individual level: Antoine Poinsot and GCC=20 > overlap? > > - Write an implementation. > > - Decide to pursue BIP > >=20 > > Responses > >=20 > > Andrew Poelstra: > > > There is a risk of confiscation of coins which have pre-signed but > > > unpublished transactions spending them to new outputs with large > > > scriptPubKeys. Due to long-standing standardness rules, and the=20 > presence > > > of P2SH (and now P2WSH) for well over a decade, I'm skeptical that an= y > > > such transactions exist. > >=20 > > PortlandHODL: This is a risk that can be incurred and likely not=20 > possible to mitigate as there could be possible chains of transactions so= =20 > even when recursively iterating over a chain there is a chance that a=20 > presigned breaks this rule. Every idea I have had from block redemption= =20 > limits on prevouts seems to just be a coverage issue where you can make t= he=20 > confiscation less likely but not completely mitigated. > >=20 > > Second, there are already TXs that effectively have been confiscated at= =20 > the policy level (P2SH Cleanstack violation) where the user can not find= =20 > any miner with a policy to accept these into their mempool. (3 years) > >=20 > > /dev /fd0 > > > so it would be great if this was restricted to OP_RETURN > >=20 > > PortlandHODL: I reject this completely as this would remove the UTXOset= =20 > omission for the scriptPubkey and encourage miners to subvert the OP_RETU= RN=20 > restriction and instead just use another op_code, this also do not hit on= =20 > some of the most important factors such as DoS mitigation and legacy scri= pt=20 > attack surface reduction. > >=20 > > Peter Todd > > > NACK ... > >=20 > > PortlandHODL: You NACK'd for the same reasons that I stated in my OP,= =20 > without including any additional context or reasoning. > >=20 > > jeremy > > > I think that this type of rule is OK if we do it as a "sunsetting"=20 > restriction -- e.g. a soft fork active for the next N blocks (N =3D e.g. = 2=20 > years, 5 years, 10 years). > >=20 > > If action is taken, this is the most reasonable approach. Alleviating= =20 > confiscatory concerns through deferral. > >=20 > > > You can argue against this example probably, but it is worth=20 > considering that absence of evidence of use is not evidence of absence of= =20 > use and I myself feel that overall our understanding of Bitcoin transacti= on=20 > programming possibilities is still early. If you don't like this example,= I=20 > can give you others (probably). > >=20 > > Agreed and this also falls into the reasoning for deciding to utilize= =20 > point 1 in your response. My thoughts on this would be along the lines of= =20 > proof of publication as this change only has the effect of stripping away= =20 > the executable portion of a script between 521 and 10_000 bytes or the=20 > published data portion if > 10_000 bytes which the same data could likely= =20 > be published in chunked segments using outpoints. > >=20 > > Andrew Poelstra: > > > Aside from proof-of-publication (i.e. data storage directly in the UT= XO > > > set) there is no usage of script which can't be equally (or better) > > > accomplished by using a Segwit v0 or Taproot script. > >=20 > > This sums up the majority of future usecase concern > >=20 > > Anthony Towns: > > > (If you restricted the change to only applying to scripts that used > > non-push operators, that would probably still provide upgrade flexibili= ty > > while also preventing potential script abuses. But it wouldn't do=20 > anything > > to prevent publishing data) > >=20 > > Could this not be done as segments in multiple outpoints using a=20 > coordination outpoint? I fail to see why publication proof must be in a= =20 > single chunk. This does though however bring another alternative to mind,= =20 > just making these outpoints unspendable but not invalidate the block=20 > through inclusion... > >=20 > > > As far as the "but contiguous data will be regulated more strictly" > > argument goes; I don't think "your honour, my offensive content has > > strings of 4d0802 every 520 bytes > >=20 > > Correct, this was never meant to resolve this issue. > >=20 > > Luke Dashjr: > > > If we're going this route, we should just close all the gaps for the= =20 > immediate future: > >=20 > > To put it nicely, this is completely beyond the scope of what is being= =20 > proposed. > >=20 > > Guus Ellenkamp: > > > If there are really so few OP_RETURN outputs more than 144 bytes, the= n > > why increase the limit if that change is so controversial? It seems > > people who want to use a larger OP_RETURN size do it anyway, even with > > the current default limits. > >=20 > > Completely off topic and irrelevant > >=20 > > Greg Tonoski: > > > Limiting the maximum size of the scriptPubKey of a transaction to 67= =20 > bytes. > >=20 > > This leave no room to deal with broken hashing algorithms and very=20 > little future upgradability for hooks. The rest of these points should be= =20 > merged with Lukes response and either hijack my thread or start a new one= =20 > with the increased scope, any approach I take will only be related to the= =20 > ScriptPubkey > >=20 > > Keagan McClelland: > > > Hard NACK on capping the witness size as that would effectively ban= =20 > large scripts even in the P2SH wrapper which undermines Bitcoin's ability= =20 > to be an effectively programmable money. > >=20 > > This has nothing to do with the witness size or even the P2SH wrapper > >=20 > > Casey Rodarmor: > > > I think that "Bitcoin could need it in the future?" might be a good= =20 > enough > > reason not to do this. > >=20 > > > Script pubkeys are the only variable-length transaction fields which= =20 > can be > > covered by input signatures, which might make them useful for future so= ft > > forks. I can imagine confidential asset schemes or post-quantum coin=20 > recovery > > schemes requiring large proofs in the outputs, where the validity of th= e=20 > proof > > determined whether or not the transaction is valid, and thus require th= e > > proofs to be in the outputs, and not just a hash commitment. > >=20 > > Would the ability to publish the data alone be enough? Example make the= =20 > output unspendable but allow for the existence of the bytes to be covered= =20 > through the signature? > >=20 > >=20 > > Antoine Poinsot: > > > Limiting the size of created scriptPubKeys is not a sufficient=20 > mitigation on its own > > I fail to see how this would not be sufficient? To DoS you need 2 thing= s=20 > inputs with ScriptPubkey redemptions + heavy op_codes that require unique= =20 > checks. Example DUPing stack element again and again doesn't work. This= =20 > then leads to the next part is you could get up to unique complex=20 > operations with the current (n) limit included per input. > >=20 > > > One of the goal of BIP54 is to address objections to Matt's earlier= =20 > proposal, notably the (in my > > opinion reasonable) confiscation concerns voiced by Russell O'Connor.= =20 > Limiting the size of > > scriptPubKeys would in this regard be moving in the opposite direction. > >=20 > > Some notes is I would actually go as far as to say the confiscation ris= k=20 > is higher with the TX limit proposed in BIP54 as we actually have proof o= f=20 > redemption of TXs that break that rule and the input set to do this alrea= dy=20 > exists on-chain no need to even wonder about the whole presigned.=20 > bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08 > >=20 > > Please let me know if I am incorrect on any of this. > >=20 > > > Furthermore, it's always possible to get the biggest bang for our buc= k=20 > in a first step > >=20 > > Agreed on bang for the buck regarding DoS. > >=20 > > My final point here would be that I would like to discuss more, and thi= s=20 > is response is from the initial view of your response and could be=20 > incomplete or incorrect, This is just my in the moment response. > >=20 > > Antoine Riard: > > > Anyway, in the sleeping pond of consensus fixes fishes, I'm more in= =20 > favor of prioritizing > > a timewarp fix and limiting dosy spends by old redeem scripts > >=20 > > The idea of congestion control is interesting, but this solution should= =20 > significantly reduce the total DoS severity of known vectors. > >=20 > > On Saturday, October 18, 2025 at 2:25:18=E2=80=AFAM UTC-7 Greg Maxwell = wrote: > >=20 > > > Limits on block construction that cross transactions make it harder t= o=20 > accurately estimate fees and greatly complicate optimal block=20 > construction-- the latter being important because smarter and more comput= er=20 > powered mining code generating higher profits is a pro centralization=20 > factor. > > >=20 > > > In terms of effectiveness the "spam" will just make itself=20 > indistinguishable from the most common transaction traffic from the=20 > perspective of such metrics-- and might well drive up "spam" levels becau= se=20 > the higher embedding cost may make some of them use more transactions. Th= e=20 > competition for these buckets by other traffic could make it effectively = a=20 > block size reduction even against very boring ordinary transactions. ...= =20 > which is probably not what most people want. > > >=20 > > > I think it's important to keep in mind that bitcoin fee levels even a= t=20 > 0.1s/vb are far beyond what other hosting services and other blockchains= =20 > cost-- so anyone still embedding data in bitcoin *really* want to be ther= e=20 > for some reason and aren't too fee sensitive or else they'd already be=20 > using something else... some are even in favor of higher costs since the= =20 > high fees are what create the scarcity needed for their seigniorage. > > >=20 > > > But yeah I think your comments on priorities are correct. > > >=20 > > >=20 > > >=20 > > > On Sat, Oct 18, 2025 at 1:20=E2=80=AFAM Antoine Riard =20 > wrote: > > >=20 > > > > Hi list, > > > >=20 > > > > Thanks to the annex covered by the signature, I don't see how the= =20 > concern about limiting > > > > the extensibility of bitcoin script with future (post-quantum)=20 > cryptographic schemes. > > > > Previous proposal of the annex were deliberately designed with=20 > variable-length fields > > > > to flexibly accomodate a wide range of things. > > > >=20 > > > > I believe there is one thing that has not been proposed to limit=20 > unpredictable utterance > > > > of spams on the blockchain, namely congestion control of categories= =20 > of outputs (e.g "fat" > > > > scriptpubkeys). Let's say P a block period, T a type of scriptpubke= y=20 > and L a limiting > > > > threshold for the number of T occurences during the period P. Beyon= d=20 > the L threshold, any > > > > additional T scriptpubkey is making the block invalid. Or=20 > alternatively, any additional > > > > T generating / spending transaction must pay some weight penalty... > > > >=20 > > > > Congestion control, which of course comes with its lot of=20 > shenanigans, is not very a novel > > > > idea as I believe it has been floated few times in the context of= =20 > lightning to solve mass > > > > closure, where channels out-priced at current feerate would have=20 > their safety timelocks scale > > > > ups. > > > >=20 > > > > No need anymore to come to social consensus on what is quantitative= =20 > "spam" or not. The blockchain > > > > would automatically throttle out the block space spamming=20 > transaction. Qualitative spam it's another > > > > question, for anyone who has ever read shannon's theory of=20 > communication only effective thing can > > > > be to limit the size of data payload. But probably we're kickly bac= k=20 > to a non-mathematically solvable > > > > linguistical question again [0]. > > > >=20 > > > > Anyway, in the sleeping pond of consensus fixes fishes, I'm more in= =20 > favor of prioritizing > > > > a timewarp fix and limiting dosy spends by old redeem scripts,=20 > rather than engaging in shooting > > > > ourselves in the foot with ill-designed "spam" consensus mitigation= s. > > > >=20 > > > > [0] If you have a soul of logician, it would be an interesting=20 > demonstration to come with > > > > to establish that we cannot come up with mathematically or=20 > cryptographically consensus means > > > > to solve qualitative "spam", which in a very pure sense is a=20 > linguistical issue. > > > >=20 > > > > Best, > > > > Antoine > > > > OTS hash:=20 > 6cb50fe36ca0ec5cb9a88517dd4ce9bb50dd6ad1d2d6a640dd4a31d72f0e4999 > > > > Le vendredi 17 octobre 2025 =C3=A0 19:45:44 UTC+1, Antoine Poinsot = a=20 > =C3=A9crit : > > > >=20 > > > > > Hi, > > > > >=20 > > > > > This approach was discussed last year when evaluating the best wa= y=20 > to mitigate DoS blocks in terms > > > > > of gains compared to confiscatory surface. Limiting the size of= =20 > created scriptPubKeys is not a > > > > > sufficient mitigation on its own, and has a non-trivial=20 > confiscatory surface. > > > > >=20 > > > > > One of the goal of BIP54 is to address objections to Matt's=20 > earlier proposal, notably the (in my > > > > > opinion reasonable) confiscation concerns voiced by Russell=20 > O'Connor. Limiting the size of > > > > > scriptPubKeys would in this regard be moving in the opposite=20 > direction. > > > > >=20 > > > > > Various approaches of limiting the size of spent scriptPubKeys=20 > were discussed, in forms that would > > > > > mitigate the confiscatory surface, to adopt in addition to (what= =20 > eventually became) the BIP54 sigops > > > > > limit. However i decided against including this additional measur= e=20 > in BIP54 because: > > > > > - of the inherent complexity of the discussed schemes, which woul= d=20 > make it hard to reason about > > > > > constructing transactions spending legacy inputs, and equally har= d=20 > to evaluate the reduction of > > > > > the confiscatory surface; > > > > > - more importantly, there is steep diminishing returns to piling= =20 > on more mitigations. The BIP54 > > > > > limit on its own prevents an externally-motivated attacker from= =20 > *unevenly* stalling the network > > > > > for dozens of minutes, and a revenue-maximizing miner from=20 > regularly stalling its competitions > > > > > for dozens of seconds, at a minimized cost in confiscatory=20 > surface. Additional mitigations reduce > > > > > the worst case validation time by a smaller factor at a higher=20 > cost in terms of confiscatory > > > > > surface. It "feels right" to further reduce those numbers, but=20 > it's less clear what the tangible > > > > > gains would be. > > > > >=20 > > > > > Furthermore, it's always possible to get the biggest bang for our= =20 > buck in a first step and going the > > > > > extra mile in a later, more controversial, soft fork. I previousl= y=20 > floated the idea of a "cleanup > > > > > v2" in private discussions, and i think besides a reduction of th= e=20 > maximum scriptPubKey size it > > > > > should feature a consensus-enforced maximum transaction size for= =20 > the reasons stated here: > > > > >=20 > https://delvingbitcoin.org/t/non-confiscatory-transaction-weight-limit/17= 32/8.=20 > I wouldn't hold my > > > > > breath on such a "cleanup v2", but it may be useful to have it=20 > documented somewhere. > > > > >=20 > > > > > I'm trying to not go into much details regarding which mitigation= s=20 > were considered in designing > > > > > BIP54, because they are tightly related to the design of various= =20 > DoS blocks. But i'm always happy to > > > > > rehash the decisions made there and (re-)consider alternative=20 > approaches on the semi-private Delving > > > > > thread [0] dedicated to this purpose. Feel free to ping me to get= =20 > access if i know you. > > > > >=20 > > > > > Best, > > > > > Antoine Poinsot > > > > >=20 > > > > > [0]:=20 > https://delvingbitcoin.org/t/worst-block-validation-time-inquiry/711 > > > > >=20 > > > > >=20 > > > > >=20 > > > > >=20 > > > > > On Friday, October 17th, 2025 at 1:12 PM, Brandon Black < > fre...@reardencode.com> wrote: > > > > >=20 > > > > > > > > > > > > > > > > > > On 2025-10-16 (Thu) at 00:06:41 +0000, Greg Maxwell wrote: > > > > > > > > > > > > > But also given that there are essentially no violations and n= o=20 > reason to > > > > > > > expect any I'm not sure the proposal is worth time relative t= o=20 > fixes of > > > > > > > actual moderately serious DOS attack issues. > > > > > > > > > > > > > > > > > > I believe this limit would also stop most (all?) of=20 > PortlandHODL's > > > > > > DoSblocks without having to make some of the other changes in= =20 > GCC. I > > > > > > think it's worthwhile to compare this approach to those propose= d=20 > by > > > > > > Antoine in solving these DoS vectors. > > > > > > > > > > > > Best, > > > > > > > > > > > > --Brandon > > > > > > > > > > > > -- > > > > > > You received this message because you are subscribed to the=20 > Google Groups "Bitcoin Development Mailing List" group. > > > > > > To unsubscribe from this group and stop receiving emails from= =20 > it, send an email to bitcoindev+...@googlegroups.com. > > > > > > To view this discussion visit=20 > https://groups.google.com/d/msgid/bitcoindev/aPJ3w6bEoaye3WJ6%40console. > > > >=20 > > > > -- > > > > You received this message because you are subscribed to the Google= =20 > Groups "Bitcoin Development Mailing List" group. > > > > To unsubscribe from this group and stop receiving emails from it,= =20 > send an email to bitcoindev+...@googlegroups.com. > > >=20 > > > > To view this discussion visit=20 > https://groups.google.com/d/msgid/bitcoindev/5135a031-a94e-49b9-ab31-a1eb= 48875ff2n%40googlegroups.com > . > >=20 > > -- > > You received this message because you are subscribed to the Google=20 > Groups "Bitcoin Development Mailing List" group. > > To unsubscribe from this group and stop receiving emails from it, send= =20 > an email to bitcoindev+...@googlegroups.com. > > To view this discussion visit=20 > https://groups.google.com/d/msgid/bitcoindev/78475572-3e52-44e4-8116-8f1a= 917995a4n%40googlegroups.com > . > --=20 You received this message because you are subscribed to the Google Groups "= Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to bitcoindev+unsubscribe@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/= f4755fb6-b031-4c60-b304-f123ba2ff473n%40googlegroups.com. ------=_Part_22219_1533187384.1761608660135 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable > MRH tracking might make that acceptable, but comes at a high cost whic= h I think would clearly not be justified.

Greg, I want to ask/ch= allenge how bad this is, this seems like a generally reusable primitive tha= t could make other upgrades more feasible that also have the same strict co= nfiscation risk profile.
IIUC, the major pain is, 1 big reindex cost += a few bytes per utxo?

Poelstra,

> I don't think t= his is a great idea -- it would be technically hard to
implement and s= low deployment indefinitely.

I would like to know how much of a = deal breaker this is in your opinion. Is MRH tracking off the table? In ter= ms of the hypothetical presigned transactions that may exist using P2MS, is= this a hard enough reason to require a MRH idea?

Greg,
> So, paradoxically this limit might increase the amount of non-pruna= ble data

I believe you're pointing out the idea of non economica= lly-rational spammers? We already see actors ignoring cheaper witness inscr= iption methods. If spam shifts to many sub-520 fake pubkey outputs (which I= believe is less harmful than stamps), that imo is a separate UTXO cost dis= cussion. (like a SF to add weight to outputs). Anywho, this point alone doe= sn't seem sufficient to add as a clear negative reason for someone opposed = to the proposal.

Thanks,
Tidwell
=
On Wednesday, October 22, 2025 at 5:= 55:58=E2=80=AFAM UTC-4 moonsettler wrote:
> Confiscation is a problem because of pres= igned transactions

Allow 10000 bytes of total scriptPubKey size in each block counting onl= y those outputs that are larger than x (520 as proposed).
The code change is pretty minimal from the most obvious implementation = of the original rule.

That makes it technically non-confiscatory. Still non-standard, but if = anyone out there so obnoxiously foot-gunned themselves, they can't clai= m they were rugged by the devs.

BR,
moonsettler

On Saturday, October 18th, 2025 at 3:15 PM, PortlandHODL <ad...@qrsnap.io> wrote:

> Hey,
>=20
> First, thank you to everyone who responded, and please continue to= do so. There were many thought provoking responses and this did shift my p= erspective quite a bit from the original post, which in of itself was the g= oal to a degree.
>=20
> I am currently only going to respond to all of the current concern= s. Acks; though I like them will be ignored unless new discoveries are incl= uded.
>=20
> Tl;dr (Portlands Perspective)
> - Confiscation is a problem because of presigned transactions
> - DoS mitigation could also occur through marking UTXOs as unspend= able if > 520 bytes, this would preserve the proof of publication.
> - Timeout / Sunset logic is compelling
> - The (n) value of acceptable needed bytes is contentious with the= lower suggested limit being 67
> - Congestion control is worth a look?
>=20
> Next Step:
> - Deeper discussion at the individual level: Antoine Poinsot and G= CC overlap?
> - Write an implementation.
> - Decide to pursue BIP
>=20
> Responses
>=20
> Andrew Poelstra:
> > There is a risk of confiscation of coins which have pre-signe= d but
> > unpublished transactions spending them to new outputs with la= rge
> > scriptPubKeys. Due to long-standing standardness rules, and t= he presence
> > of P2SH (and now P2WSH) for well over a decade, I'm skept= ical that any
> > such transactions exist.
>=20
> PortlandHODL: This is a risk that can be incurred and likely not p= ossible to mitigate as there could be possible chains of transactions so ev= en when recursively iterating over a chain there is a chance that a presign= ed breaks this rule. Every idea I have had from block redemption limits on = prevouts seems to just be a coverage issue where you can make the confiscat= ion less likely but not completely mitigated.
>=20
> Second, there are already TXs that effectively have been confiscat= ed at the policy level (P2SH Cleanstack violation) where the user can not f= ind any miner with a policy to accept these into their mempool. (3 years)
>=20
> /dev /fd0
> > so it would be great if this was restricted to OP_RETURN
>=20
> PortlandHODL: I reject this completely as this would remove the UT= XOset omission for the scriptPubkey and encourage miners to subvert the OP_= RETURN restriction and instead just use another op_code, this also do not h= it on some of the most important factors such as DoS mitigation and legacy = script attack surface reduction.
>=20
> Peter Todd
> > NACK ...
>=20
> PortlandHODL: You NACK'd for the same reasons that I stated in= my OP, without including any additional context or reasoning.
>=20
> jeremy
> > I think that this type of rule is OK if we do it as a "s= unsetting" restriction -- e.g. a soft fork active for the next N block= s (N =3D e.g. 2 years, 5 years, 10 years).
>=20
> If action is taken, this is the most reasonable approach. Alleviat= ing confiscatory concerns through deferral.
>=20
> > You can argue against this example probably, but it is worth = considering that absence of evidence of use is not evidence of absence of u= se and I myself feel that overall our understanding of Bitcoin transaction = programming possibilities is still early. If you don't like this exampl= e, I can give you others (probably).
>=20
> Agreed and this also falls into the reasoning for deciding to util= ize point 1 in your response. My thoughts on this would be along the lines = of proof of publication as this change only has the effect of stripping awa= y the executable portion of a script between 521 and 10_000 bytes or the pu= blished data portion if > 10_000 bytes which the same data could likely = be published in chunked segments using outpoints.
>=20
> Andrew Poelstra:
> > Aside from proof-of-publication (i.e. data storage directly i= n the UTXO
> > set) there is no usage of script which can't be equally (= or better)
> > accomplished by using a Segwit v0 or Taproot script.
>=20
> This sums up the majority of future usecase concern
>=20
> Anthony Towns:
> > (If you restricted the change to only applying to scripts tha= t used
> non-push operators, that would probably still provide upgrade flex= ibility
> while also preventing potential script abuses. But it wouldn't= do anything
> to prevent publishing data)
>=20
> Could this not be done as segments in multiple outpoints using a c= oordination outpoint? I fail to see why publication proof must be in a sing= le chunk. This does though however bring another alternative to mind, just = making these outpoints unspendable but not invalidate the block through inc= lusion...
>=20
> > As far as the "but contiguous data will be regulated mor= e strictly"
> argument goes; I don't think "your honour, my offensive c= ontent has
> strings of 4d0802 every 520 bytes
>=20
> Correct, this was never meant to resolve this issue.
>=20
> Luke Dashjr:
> > If we're going this route, we should just close all the g= aps for the immediate future:
>=20
> To put it nicely, this is completely beyond the scope of what is b= eing proposed.
>=20
> Guus Ellenkamp:
> > If there are really so few OP_RETURN outputs more than 144 by= tes, then
> why increase the limit if that change is so controversial? It seem= s
> people who want to use a larger OP_RETURN size do it anyway, even = with
> the current default limits.
>=20
> Completely off topic and irrelevant
>=20
> Greg Tonoski:
> > Limiting the maximum size of the scriptPubKey of a transactio= n to 67 bytes.
>=20
> This leave no room to deal with broken hashing algorithms and very= little future upgradability for hooks. The rest of these points should be = merged with Lukes response and either hijack my thread or start a new one w= ith the increased scope, any approach I take will only be related to the Sc= riptPubkey
>=20
> Keagan McClelland:
> > Hard NACK on capping the witness size as that would effective= ly ban large scripts even in the P2SH wrapper which undermines Bitcoin'= s ability to be an effectively programmable money.
>=20
> This has nothing to do with the witness size or even the P2SH wrap= per
>=20
> Casey Rodarmor:
> > I think that "Bitcoin could need it in the future?"= might be a good enough
> reason not to do this.
>=20
> > Script pubkeys are the only variable-length transaction field= s which can be
> covered by input signatures, which might make them useful for futu= re soft
> forks. I can imagine confidential asset schemes or post-quantum co= in recovery
> schemes requiring large proofs in the outputs, where the validity = of the proof
> determined whether or not the transaction is valid, and thus requi= re the
> proofs to be in the outputs, and not just a hash commitment.
>=20
> Would the ability to publish the data alone be enough? Example mak= e the output unspendable but allow for the existence of the bytes to be cov= ered through the signature?
>=20
>=20
> Antoine Poinsot:
> > Limiting the size of created scriptPubKeys is not a sufficien= t mitigation on its own
> I fail to see how this would not be sufficient? To DoS you need 2 = things inputs with ScriptPubkey redemptions + heavy op_codes that require u= nique checks. Example DUPing stack element again and again doesn't work= . This then leads to the next part is you could get up to unique complex op= erations with the current (n) limit included per input.
>=20
> > One of the goal of BIP54 is to address objections to Matt'= ;s earlier proposal, notably the (in my
> opinion reasonable) confiscation concerns voiced by Russell O'= Connor. Limiting the size of
> scriptPubKeys would in this regard be moving in the opposite direc= tion.
>=20
> Some notes is I would actually go as far as to say the confiscatio= n risk is higher with the TX limit proposed in BIP54 as we actually have pr= oof of redemption of TXs that break that rule and the input set to do this = already exists on-chain no need to even wonder about the whole presigned. b= b41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08
>=20
> Please let me know if I am incorrect on any of this.
>=20
> > Furthermore, it's always possible to get the biggest bang= for our buck in a first step
>=20
> Agreed on bang for the buck regarding DoS.
>=20
> My final point here would be that I would like to discuss more, an= d this is response is from the initial view of your response and could be i= ncomplete or incorrect, This is just my in the moment response.
>=20
> Antoine Riard:
> > Anyway, in the sleeping pond of consensus fixes fishes, I'= ;m more in favor of prioritizing
> a timewarp fix and limiting dosy spends by old redeem scripts
>=20
> The idea of congestion control is interesting, but this solution s= hould significantly reduce the total DoS severity of known vectors.
>=20
> On Saturday, October 18, 2025 at 2:25:18=E2=80=AFAM UTC-7 Greg Max= well wrote:
>=20
> > Limits on block construction that cross transactions make it = harder to accurately estimate fees and greatly complicate optimal block con= struction-- the latter being important because smarter and more computer po= wered mining code generating higher profits is a pro centralization factor.
> >=20
> > In terms of effectiveness the "spam" will just make= itself indistinguishable from the most common transaction traffic from the= perspective of such metrics-- and might well drive up "spam" lev= els because the higher embedding cost may make some of them use more transa= ctions. The competition for these buckets by other traffic could make it ef= fectively a block size reduction even against very boring ordinary transact= ions. ... which is probably not what most people want.
> >=20
> > I think it's important to keep in mind that bitcoin fee l= evels even at 0.1s/vb are far beyond what other hosting services and other = blockchains cost-- so anyone still embedding data in bitcoin *really* want = to be there for some reason and aren't too fee sensitive or else they&#= 39;d already be using something else... some are even in favor of higher co= sts since the high fees are what create the scarcity needed for their seign= iorage.
> >=20
> > But yeah I think your comments on priorities are correct.
> >=20
> >=20
> >=20
> > On Sat, Oct 18, 2025 at 1:20=E2=80=AFAM Antoine Riard <antoin...@gmail.com> wrote:
> >=20
> > > Hi list,
> > >=20
> > > Thanks to the annex covered by the signature, I don'= t see how the concern about limiting
> > > the extensibility of bitcoin script with future (post-qu= antum) cryptographic schemes.
> > > Previous proposal of the annex were deliberately designe= d with variable-length fields
> > > to flexibly accomodate a wide range of things.
> > >=20
> > > I believe there is one thing that has not been proposed = to limit unpredictable utterance
> > > of spams on the blockchain, namely congestion control of= categories of outputs (e.g "fat"
> > > scriptpubkeys). Let's say P a block period, T a type= of scriptpubkey and L a limiting
> > > threshold for the number of T occurences during the peri= od P. Beyond the L threshold, any
> > > additional T scriptpubkey is making the block invalid. O= r alternatively, any additional
> > > T generating / spending transaction must pay some weight= penalty...
> > >=20
> > > Congestion control, which of course comes with its lot o= f shenanigans, is not very a novel
> > > idea as I believe it has been floated few times in the c= ontext of lightning to solve mass
> > > closure, where channels out-priced at current feerate wo= uld have their safety timelocks scale
> > > ups.
> > >=20
> > > No need anymore to come to social consensus on what is q= uantitative "spam" or not. The blockchain
> > > would automatically throttle out the block space spammin= g transaction. Qualitative spam it's another
> > > question, for anyone who has ever read shannon's the= ory of communication only effective thing can
> > > be to limit the size of data payload. But probably we= 9;re kickly back to a non-mathematically solvable
> > > linguistical question again [0].
> > >=20
> > > Anyway, in the sleeping pond of consensus fixes fishes, = I'm more in favor of prioritizing
> > > a timewarp fix and limiting dosy spends by old redeem sc= ripts, rather than engaging in shooting
> > > ourselves in the foot with ill-designed "spam"= consensus mitigations.
> > >=20
> > > [0] If you have a soul of logician, it would be an inter= esting demonstration to come with
> > > to establish that we cannot come up with mathematically = or cryptographically consensus means
> > > to solve qualitative "spam", which in a very p= ure sense is a linguistical issue.
> > >=20
> > > Best,
> > > Antoine
> > > OTS hash: 6cb50fe36ca0ec5cb9a88517dd4ce9bb50dd6ad1d2d6a6= 40dd4a31d72f0e4999
> > > Le vendredi 17 octobre 2025 =C3=A0 19:45:44 UTC+1, Antoi= ne Poinsot a =C3=A9crit :
> > >=20
> > > > Hi,
> > > >=20
> > > > This approach was discussed last year when evaluati= ng the best way to mitigate DoS blocks in terms
> > > > of gains compared to confiscatory surface. Limiting= the size of created scriptPubKeys is not a
> > > > sufficient mitigation on its own, and has a non-tri= vial confiscatory surface.
> > > >=20
> > > > One of the goal of BIP54 is to address objections t= o Matt's earlier proposal, notably the (in my
> > > > opinion reasonable) confiscation concerns voiced by= Russell O'Connor. Limiting the size of
> > > > scriptPubKeys would in this regard be moving in the= opposite direction.
> > > >=20
> > > > Various approaches of limiting the size of spent sc= riptPubKeys were discussed, in forms that would
> > > > mitigate the confiscatory surface, to adopt in addi= tion to (what eventually became) the BIP54 sigops
> > > > limit. However i decided against including this add= itional measure in BIP54 because:
> > > > - of the inherent complexity of the discussed schem= es, which would make it hard to reason about
> > > > constructing transactions spending legacy inputs, a= nd equally hard to evaluate the reduction of
> > > > the confiscatory surface;
> > > > - more importantly, there is steep diminishing retu= rns to piling on more mitigations. The BIP54
> > > > limit on its own prevents an externally-motivated a= ttacker from *unevenly* stalling the network
> > > > for dozens of minutes, and a revenue-maximizing min= er from regularly stalling its competitions
> > > > for dozens of seconds, at a minimized cost in confi= scatory surface. Additional mitigations reduce
> > > > the worst case validation time by a smaller factor = at a higher cost in terms of confiscatory
> > > > surface. It "feels right" to further redu= ce those numbers, but it's less clear what the tangible
> > > > gains would be.
> > > >=20
> > > > Furthermore, it's always possible to get the bi= ggest bang for our buck in a first step and going the
> > > > extra mile in a later, more controversial, soft for= k. I previously floated the idea of a "cleanup
> > > > v2" in private discussions, and i think beside= s a reduction of the maximum scriptPubKey size it
> > > > should feature a consensus-enforced maximum transac= tion size for the reasons stated here:
> > > > https://delvingbitcoin.org/t/non-confiscatory-transaction-weight-limit= /1732/8. I wouldn't hold my
> > > > breath on such a "cleanup v2", but it may= be useful to have it documented somewhere.
> > > >=20
> > > > I'm trying to not go into much details regardin= g which mitigations were considered in designing
> > > > BIP54, because they are tightly related to the desi= gn of various DoS blocks. But i'm always happy to
> > > > rehash the decisions made there and (re-)consider a= lternative approaches on the semi-private Delving
> > > > thread [0] dedicated to this purpose. Feel free to = ping me to get access if i know you.
> > > >=20
> > > > Best,
> > > > Antoine Poinsot
> > > >=20
> > > > [0]: https://= delvingbitcoin.org/t/worst-block-validation-time-inquiry/711
> > > >=20
> > > >=20
> > > >=20
> > > >=20
> > > > On Friday, October 17th, 2025 at 1:12 PM, Brandon B= lack <fre...@reardencode.com<= /a>> wrote:
> > > >=20
> > > > >
> > > > >
> > > > > On 2025-10-16 (Thu) at 00:06:41 +0000, Greg Ma= xwell wrote:
> > > > >
> > > > > > But also given that there are essentially= no violations and no reason to
> > > > > > expect any I'm not sure the proposal = is worth time relative to fixes of
> > > > > > actual moderately serious DOS attack issu= es.
> > > > >
> > > > >
> > > > > I believe this limit would also stop most (all= ?) of PortlandHODL's
> > > > > DoSblocks without having to make some of the o= ther changes in GCC. I
> > > > > think it's worthwhile to compare this appr= oach to those proposed by
> > > > > Antoine in solving these DoS vectors.
> > > > >
> > > > > Best,
> > > > >
> > > > > --Brandon
> > > > >
> > > > > --
> > > > > You received this message because you are subs= cribed to the Google Groups "Bitcoin Development Mailing List" gr= oup.
> > > > > To unsubscribe from this group and stop receiv= ing emails from it, send an email to bitcoindev+...@googlegroups.com.
> > > > > To view this discussion visit https://groups.google.com/d/msgid/bitcoind= ev/aPJ3w6bEoaye3WJ6%40console.
> > >=20
> > > --
> > > You received this message because you are subscribed to = the Google Groups "Bitcoin Development Mailing List" group.
> > > To unsubscribe from this group and stop receiving emails= from it, send an email to bitco= indev+...@googlegroups.com.
> >=20
> > > To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/5135a031-a94e-49b9-ab31-a= 1eb48875ff2n%40googlegroups.com.
>=20
> --
> You received this message because you are subscribed to the Google= Groups "Bitcoin Development Mailing List" group.
> To unsubscribe from this group and stop receiving emails from it, = send an email to bitcoindev+...@= googlegroups.com.
> To view this discussion visit https= ://groups.google.com/d/msgid/bitcoindev/78475572-3e52-44e4-8116-8f1a917995a= 4n%40googlegroups.com.

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