From: Sergio Demian Lerner <sergio.d.lerner@gmail.com>
To: Greg Sanders <gsanders87@gmail.com>
Cc: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: Re: [bitcoindev] Re: Subject: Eltoo / LN-Symmetry on Inquisition Signet: BIP 118 + 3-Round State Chain (APO+CTV)
Date: Tue, 14 Apr 2026 15:58:32 -0300 [thread overview]
Message-ID: <CAKzdR-ok1jwtXOYaAPBw1fhpavL=P+2jsT+VcKc9OwW6bhpRFw@mail.gmail.com> (raw)
In-Reply-To: <494c0600-2daa-4500-8e49-bf36efbf2625n@googlegroups.com>
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If you want to do have similar functionality to Eltoo without soft-forks,
you can use OTC-PCs:
OTS-PC: OTS-based Payment Channels for the Lightning Network
https://arxiv.org/abs/2511.04021
regards, Sergio
On Tue, Apr 14, 2026 at 12:54 PM Greg Sanders <gsanders87@gmail.com> wrote:
> In case anyone is interested, a few months ago I resurrected my old
> ln-symmetry branch of CLN with various improvements and examples, thanks to
> LLM doing the heavy lifting for revival.
>
> https://delvingbitcoin.org/t/ln-symmetry-project-recap/359/17
>
> Aside from APO implementation, I also vibed a CSFS+TH+IK variant, though
> it cannot be tested on signet directly until OP_TEMPLATEHASH is activated.
> It's a drop-in replacement for CTV, if anyone cares to adapt it.
>
> Greg
>
> On Tuesday, April 14, 2026 at 5:18:24 AM UTC-4 aaron.recompile wrote:
>
>> Hi List,
>>
>> I ran a three-round Eltoo-style state chain on Bitcoin Inquisition 29.2
>> signet using APO (BIP 118) for state updates and CTV for settlement.
>> Six transactions, all confirmed on-chain.
>>
>> An independent Python implementation of the BIP 118 sighash (Msg118 /
>> Ext118) was cross-validated against Inquisition's C++ consensus engine.
>> If the Python digest disagrees with Core's, the transaction is rejected.
>> It wasn't.
>>
>> Construction
>> ------------
>> Each state UTXO is a three-leaf Taproot tree:
>>
>> leaf 1 -- ctv_uhpo: <template_hash> OP_CHECKTEMPLATEVERIFY
>> leaf 2 -- apo_update: <0x01||xonly> OP_CHECKSIG (BIP 118)
>> leaf 3 -- csv_escape: <sequence> OP_CHECKSEQUENCEVERIFY OP_DROP
>> <pubkey> OP_CHECKSIG
>>
>> CTV locks each state's payout distribution
>> as a template hash. APO rebinding advances state. When an APO update
>> spends state vN, vN's CTV leaf
>> loses its only viable input and can never settle. Only the latest state
>> can produce a valid settlement. This is the Eltoo invariant, executed
>> end-to-end with current tooling.
>>
>> Confirmed txids (Inquisition signet)
>> -------------------------------------
>> Fund → State v1:
>> 386dbb6aa23fcc35a69d34e3c0f760b185482467abc936196d3def19d54a9c41
>> APO update v1 → v2:
>> 096e31ccbd8f5460b2730ec4f757ee1b01acf9dde3e3b8cb55fbb534fe195601
>> APO update v2 → v3:
>> 091309b73e299436ff12fceda7e54e28c6f1817fdf3405bca3343ad15198d7f6
>> CTV settlement:
>> 13957f49d01aa21ed2aa28df7aa78f357d51a2a2fbfb434af05fdc75ad0ff9b7
>>
>> Rebind A (signed):
>> 03c0577c1d47da32804d098187644d0eee18b448aded2f427cd02193c070f3a4
>> Rebind B (witness copied):
>> 46091190c74d8fd4b39be67a2e945a19b021850e7f8d9e378f5eb11722ae1a43
>>
>> Rebind A and B share an identical witness stack — same 65-byte signature
>> (sighash flag 0x41), same leaf script, same control block — spending two
>> different UTXOs without re-signing. Outputs remain committed: changing
>> the output address in Rebind B causes script verification failure.
>> The last two transactions are a standalone rebinding demonstration,
>> not part of the state chain above.
>>
>> Links
>> ------
>> BIP 118 signing primitive and rebinding proof (Delving Bitcoin):
>>
>> https://delvingbitcoin.org/t/bip-118-signing-from-scratch-on-chain-rebinding-proof/2411
>>
>> Eltoo state chain construction (Delving Bitcoin):
>>
>> https://delvingbitcoin.org/t/eltoo-state-chain-on-signet-three-rounds-six-transactions-apo-ctv/2413
>>
>> Source code (btcaaron, examples/braidpool/):
>> https://github.com/aaron-recompile/btcaaron
>>
>> Happy to discuss the construction or the CTV+CSFS gap.
>>
>> Aaron Zhang
>>
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prev parent reply other threads:[~2026-04-14 19:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-14 4:04 [bitcoindev] " aaron.recompile
2026-04-14 13:57 ` [bitcoindev] " Greg Sanders
2026-04-14 18:17 ` aaron.recompile
2026-04-14 18:58 ` Sergio Demian Lerner [this message]
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