From a818c0506599e201347f90446a08e005ca3e143a Mon Sep 17 00:00:00 2001 From: Orfeas Stefanos Thyfronitis Litos Date: Thu, 13 Aug 2026 22:46:41 -0400 Subject: [PATCH 1/4] Mention more BIP 448 benefits, compare it with APO - Mention delegation and DLC optimisation - Mention that it provides building blocks for future updates - Compare with APO that doesn't offer the above --- bip-0448.md | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/bip-0448.md b/bip-0448.md index 06804e218f..5c88d7b412 100644 --- a/bip-0448.md +++ b/bip-0448.md @@ -40,6 +40,9 @@ enables simplifications for 2-party channels such as [Daric][daric-channels], an protocols, as illustrated by the Ark variant "[Erk][ark-erk]" or the [dramatic simplification][greg-rebindable-ptlcs] they bring to upgrading today's Lightning to [Point Time Locked Contracts][optech-ptlcs]. +These features also unlock further applications, such as [delegation][delegation] and [optimized DLCs][dlc]. +Furthermore, they will serve as building blocks for further applications enabled by future soft forks down the line. + `OP_INTERNALKEY` allows to push the [Taproot][taproot-bip] internal key on the stack. This is a natural and extremely simple optimisation for rebindable signatures. @@ -67,6 +70,10 @@ an increased risk surface, notably in terms of implementation complexity. As the demonstrated to enable new important use cases or substantially improve existing ones beyond this proposal, we favour the minimal approach. +[BIP 118 `SIGHASH_ANYPREVOUT`][apo-bip] also enables rebindable signatures and their applications. However, as a less +modular operation, it does not enable delegation, optimize DLCs, or can serve as a building block for further soft +forks. + An alternative to [BIP 446 `OP_TEMPLATEHASH`][templatehash-bip] is [BIP 119 `OP_CHECKTEMPLATEVERIFY`][ctv-bip]. This proposal favours the minimal approach of [BIP 446 `OP_TEMPLATEHASH`][templatehash-bip] that does not modify legacy scripting contexts and reuses the existing Taproot signature hashes. See [the rationale section of BIP @@ -104,3 +111,6 @@ This document is licensed under the Creative Commons CC0 1.0 Universal license. [greg-rebindable-ptlcs]: https://gist.github.com/instagibbs/1d02d0251640c250ceea1c66665ec163 [daric-channels]: https://eprint.iacr.org/2022/1295 [statechains-optech]: https://bitcoinops.org/en/topics/statechains/ +[apo-bip]: bip-0118.mediawiki +[delegation]: bip-0348.md#delegation +[dlc]: https://gnusha.org/pi/bitcoindev/CAH5Bsr2vxL3FWXnJTszMQj83jTVdRvvuVpimEfY7JpFCyP1AZA@mail.gmail.com/ From 12e4e450bc0dfb35d3a818a9a4cebbe575fb2c56 Mon Sep 17 00:00:00 2001 From: Orfeas Stefanos Thyfronitis Litos Date: Fri, 14 Aug 2026 12:25:07 -0400 Subject: [PATCH 2/4] Clarify phrasing --- bip-0448.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/bip-0448.md b/bip-0448.md index 5c88d7b412..11e49ba7ea 100644 --- a/bip-0448.md +++ b/bip-0448.md @@ -71,7 +71,7 @@ demonstrated to enable new important use cases or substantially improve existing the minimal approach. [BIP 118 `SIGHASH_ANYPREVOUT`][apo-bip] also enables rebindable signatures and their applications. However, as a less -modular operation, it does not enable delegation, optimize DLCs, or can serve as a building block for further soft +modular operation, it does not enable delegation, it does not optimize DLCs, and it cannot serve as a building block for further soft forks. An alternative to [BIP 446 `OP_TEMPLATEHASH`][templatehash-bip] is [BIP 119 `OP_CHECKTEMPLATEVERIFY`][ctv-bip]. This From d93c2a70cc15801788b1214b3c95e73b9c9fd930 Mon Sep 17 00:00:00 2001 From: Orfeas Stefanos Thyfronitis Litos Date: Wed, 2 Sep 2026 15:04:34 +0300 Subject: [PATCH 3/4] Remove DLC mentions --- bip-0448.md | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/bip-0448.md b/bip-0448.md index 11e49ba7ea..5bc1706d86 100644 --- a/bip-0448.md +++ b/bip-0448.md @@ -40,7 +40,7 @@ enables simplifications for 2-party channels such as [Daric][daric-channels], an protocols, as illustrated by the Ark variant "[Erk][ark-erk]" or the [dramatic simplification][greg-rebindable-ptlcs] they bring to upgrading today's Lightning to [Point Time Locked Contracts][optech-ptlcs]. -These features also unlock further applications, such as [delegation][delegation] and [optimized DLCs][dlc]. +These features also unlock further applications, such as [delegation][delegation]. Furthermore, they will serve as building blocks for further applications enabled by future soft forks down the line. `OP_INTERNALKEY` allows to push the [Taproot][taproot-bip] internal key on the stack. This is a natural and extremely @@ -71,7 +71,7 @@ demonstrated to enable new important use cases or substantially improve existing the minimal approach. [BIP 118 `SIGHASH_ANYPREVOUT`][apo-bip] also enables rebindable signatures and their applications. However, as a less -modular operation, it does not enable delegation, it does not optimize DLCs, and it cannot serve as a building block for further soft +modular operation, it does not enable delegation, and it cannot serve as a building block for further soft forks. An alternative to [BIP 446 `OP_TEMPLATEHASH`][templatehash-bip] is [BIP 119 `OP_CHECKTEMPLATEVERIFY`][ctv-bip]. This @@ -113,4 +113,3 @@ This document is licensed under the Creative Commons CC0 1.0 Universal license. [statechains-optech]: https://bitcoinops.org/en/topics/statechains/ [apo-bip]: bip-0118.mediawiki [delegation]: bip-0348.md#delegation -[dlc]: https://gnusha.org/pi/bitcoindev/CAH5Bsr2vxL3FWXnJTszMQj83jTVdRvvuVpimEfY7JpFCyP1AZA@mail.gmail.com/ From 7ac1cce7ec0e68a093e8b4fbfb335b9ccb6ce40d Mon Sep 17 00:00:00 2001 From: Orfeas Stefanos Thyfronitis Litos Date: Wed, 2 Sep 2026 18:19:18 +0300 Subject: [PATCH 4/4] Rephrase BIP 448 comparison with APO --- bip-0448.md | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/bip-0448.md b/bip-0448.md index 5bc1706d86..072b3d0c6b 100644 --- a/bip-0448.md +++ b/bip-0448.md @@ -70,9 +70,12 @@ an increased risk surface, notably in terms of implementation complexity. As the demonstrated to enable new important use cases or substantially improve existing ones beyond this proposal, we favour the minimal approach. -[BIP 118 `SIGHASH_ANYPREVOUT`][apo-bip] also enables rebindable signatures and their applications. However, as a less -modular operation, it does not enable delegation, and it cannot serve as a building block for further soft -forks. +In terms of new functionality, [BIP 118 `SIGHASH_ANYPREVOUT`][apo-bip] enables rebindable signatures and their applications, including covenants inexpressible under the current proposal. +However, it does not enable delegation. + +In terms of semantics, BIP 118 extends Bitcoin semantics in subtle ways, making future updates building on it tricky to reason about. +On the other hand, the new operations proposed here are intuitive and, since they are opcodes, semantic changes are confined inside of Script. +As such, they add useful functionality while keeping under control the extra cognitive load needed to design future updates. An alternative to [BIP 446 `OP_TEMPLATEHASH`][templatehash-bip] is [BIP 119 `OP_CHECKTEMPLATEVERIFY`][ctv-bip]. This proposal favours the minimal approach of [BIP 446 `OP_TEMPLATEHASH`][templatehash-bip] that does not modify legacy