[BIP Proposal] Reduced Data Temporary Softfork

[dath...@proton.me]

Hi list -

Due to Bitcoin Core v30 gaining in popularity, it has become necessary to move forward on luke-jr's ML proposal to temporarily limit arbitrary data at the consensus level, which so far has 3 weeks with no objections:

https://github.com/bitcoin/bips/pull/2017

The idea is to strongly re-affirm in consensus that bitcoin is money, not data storage. It is implemented as a temporary softfork that can activate in one of two different ways: proactive, or reactive.

After a year, the soft fork expires, giving us time to come up with a more permanent solution.

The timeline is a bit tight, but I think everyone has incentives to support a quick and orderly activation.

Please feel free to leave a comment on the PR or reach out to me over email with any feedback. 

There is much work still to do, so if you have some technical skills and would like to join in the effort with dev/testing, please reach out as well.

Bitcoin is money.

Sincerely,

Dathon Ohm

[Jameson Lopp]

It's quite clear from the PR discussion that there are a multitude of contentious issues at play with this proposal.

Even aside from all of the technical concerns, the underlying implication of using legal coercion to require miners and other network participants to comply with arbitrary legal and moral frameworks makes it a non-starter in my opinion.

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[Peter Todd]

On Sat, Oct 25, 2025 at 08:43:11PM +0000, dathonohm via Bitcoin Development Mailing List wrote:
> Hi list -
>

> Due to Bitcoin Core v30 gaining in popularity, it has become necessary to move forward on [luke-jr's ML proposal](https://github.com/bitcoin/bips/pull/2017) to temporarily limit arbitrary data at the consensus level, which so far has 3 weeks with no objections:
>
> https://github.com/bitcoin/bips/pull/2017

Transaction 8e2ee13d2a19951c2777bb3a54f0cb69a2f76dae8baa954cd86149ed1138cb6c
contains the full text of this BIP as of writing(1), while simultaneously being
compliant with that BIP.

Clearly, this approach is ineffective.

1) https://github.com/bitcoin/bips/blob/3c718237072c107ced8c3531a487354fbdae55df/bip-%3F%3F%3F%3F.mediawiki

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https://petertodd.org 'peter'[:-1]@petertodd.org

[dath...@proton.me]

Peter -

Thank you for demonstrating what non-contiguous data looks like.

I trust you when you say that you can parse the BIP's contents from this transaction, but all it looks like to me (and the Bitcoin network) is a UTXO broken into 31 pieces then (mostly) re-consolidated into a 0-length OP_RETURN, sending all ~100 USD in fees to the miner.

Since legally hazardous content can be generated from any input data, including your 30-input consolidation transaction (as long as the correct third-party program is used), it would not make sense to hold node operators legally responsible for storing and distributing such input data.

However, if Bitcoin provides an officially supported method of storing arbitrary data (i.e., OP_RETURN), and the capacity of that method is large enough to store hazardous content in a contiguous format (an increase to 100kB is currently underway as Bitcoin Core 30 gains adoption), then one does not need to misinterpret the data in order to view the content. In that case, node operators could conceivably be held responsible for possession and distribution.

Since arbitrary data storage does nothing to benefit Bitcoin as permissionless money, there is no good reason to force this additional legal risk on node operators, who already face enough challenges as it is.

Best,

Dathon

On Sunday, October 26th, 2025 at 4:43 PM, Peter Todd <pe...@petertodd.org> wrote:

> On Sat, Oct 25, 2025 at 08:43:11PM +0000, dathonohm via Bitcoin Development Mailing List wrote:
>
> > Hi list -
> >

> > Due to Bitcoin Core v30 gaining in popularity, it has become necessary to move forward on luke-jr's ML proposal to temporarily limit arbitrary data at the consensus level, which so far has 3 weeks with no objections:

> >
> > https://github.com/bitcoin/bips/pull/2017
>
>
> Transaction 8e2ee13d2a19951c2777bb3a54f0cb69a2f76dae8baa954cd86149ed1138cb6c
> contains the full text of this BIP as of writing(1), while simultaneously being
> compliant with that BIP.
>
> Clearly, this approach is ineffective.
>
> 1) https://github.com/bitcoin/bips/blob/3c718237072c107ced8c3531a487354fbdae55df/bip-%3F%3F%3F%3F.mediawiki
>
> --
> https://petertodd.org 'peter'[:-1]@petertodd.org
>

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> To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/aP6gYSnte7J86g0p%40petertodd.org.

[dath...@proton.me]

Jameson -

You mention "technical concerns" but don't give any examples. Would you mind sharing one?

You also mention "the underlying implication of using legal coercion to require miners and other network participants to comply with arbitrary legal and moral frameworks", but I don't think the BIP implies this at all.

The BIP merely highlights a legal risk Bitcoin Core 30 has created for node operators for no good reason, and attempts to eliminate it. No "coercion" is implied. You and anyone else who are fine shouldering this risk are free to stay on the old data-friendly chain. I doubt you will have much company, though.

Best,

Dathon

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[TheWrlck]

I’m not convinced that restricting or discouraging non-transactional data is the right approach. While limiting data size may reduce certain abuses, it also constrains legitimate use cases that leverage Bitcoin’s data-carrying capabilities (e.g. commitments, metadata, or novel protocols). From a consensus-layer perspective, Bitcoin should remain neutral about how data is interpreted or used, as long as it follows the defined rules and pays the required fees. Imposing normative judgments about "spam" risks introducing subjective policy where objective validation should suffice.

[Jameson Lopp]

On Mon, Oct 27, 2025 at 12:22 AM <dath...@proton.me> wrote:

Jameson -

You mention "technical concerns" but don't give any examples. Would you mind sharing one?

Two of the biggest technical concerns are that the proposed changes are confiscatory for certain scripts and the fact that the reactive chain reorganization logic actually makes it possible for anyone to trivially double spend their coins by triggering a reorganization.

 

You also mention "the underlying implication of using legal coercion to require miners and other network participants to comply with arbitrary legal and moral frameworks", but I don't think the BIP implies this at all.

I quote the BIP:

"rejecting this softfork may subject you to legal or moral consequences"

This vague, hand waving fear mongering is the underlying implication of legal coercion to which I referred. It's not appropriate for a technical specification.

[Jal Toorey]

"bitcoin is money"

The definition of what is money is extremely subjective.  The history of it shows this (not the history saifedean paints). Trying to direct the development to capture a definition of money opens a huge attack vector. It's not different than trying to decide what is spam. 

Also what is the difference between the bashers slogan that bitcoin is p2p money and "bitcoin is money"  They seem like the same thing? 

[Kyle Stout]

Dathon,

> if Bitcoin provides an officially supported method of storing arbitrary data (i.e., OP_RETURN), and the capacity of that method is large enough to store hazardous content in a contiguous format (an increase to 100kB is currently underway as Bitcoin Core 30 gains adoption), then one does not need to misinterpret the data in order to view the content.

This seems to be the crux of your argument. I believe it is misleading and technically unsound. It's technical theater that creates a distinction without any meaningful difference.

First, Bitcoin has no concept of a file viewer. To interpret any embedded data other to validate it against Bitcoin's rules, you must use a third party tool. Practically speaking, the differences are negligible in terms of technical difficulty, as humorously demonstrated here: https://x.com/rot13maxi/status/1963318690759192622 . Contiguous or not, you're file carving. 

Second, by definition, you're misinterpreting the data vis-a-vis Bitcoin since it has no native concept of 'image', 'video', etc. Arbitrary bytes are meaningless. The purpose of having OP_RETURN as a standard output is to protect the UTXO set from being abused. It isn't some kind of 'blessing' to store files. That's absurd. As you admit, it's impossible to stop people from writing arbitrary bytes to the blockchain, so this is damage mitigation, not an invitation.

Third, contiguity is not a legally meaningful predicate. "Your honor, we tried to limit the contiguous bytes!" is simply not going to fly. The bytes exist either way, and they must be interpreted by third party software either way. If anything, this path is going to represent a voluntary self-policing that will result in more culpability. Right now, arbitrary bytes don't mean anything in Bitcoin. If it's valid, it's valid. Nodes relay opaque protocol data. If you insist on only accepting 'approved' arbitrary bytes, you're opening the door to a knowledge/intent accusation.

Regards,

Kyle

[Greg Maxwell]

The only consensus normative data encoding in Bitcoin is the order data goes into hashes.  The representations in memory, rpc, in the p2p network, etc. are already different and could be made arbitrarily different without any consensus change.  Case in point:  the data is now normally encrypted on disk and in P2P.  There are also proposals such as BIP 337: https://github.com/bitcoin/bips/blob/master/bip-0337.mediawiki  none of these things are consensus changes-- many aren't even bippable because they don't have interoperability considerations (e.g. representations on disk/memory).

Forget for a moment the (un)likelyhood that the concerns being discussed are meaningfully modulated by exactly how data is represented in p2p, memory, rpc, disk, etc.. for assumption just assume they are.

If so, the correct move would be to change those encodings rather than any consensus rule change--- particularly because any consensus rule method will simply be evaded, and can't provide the level of swizzling that changing the encoding can accomplish.  Encoding changes are also substantially non-coercive: people who think they're valuable can adopt them and leave other people alone.

Good news for everyone except those who consider coercing others to be a terminal goal. 

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