Hi Poinsot,

Thanks for the collection of historical txn hitting the proposed new limit.

The only long-term downside coming immediately out of mind, if the rule 
becomes consensus
in the future, it's the implicit limitation it would make on the 
multi-party dimensions
of off-chain constructions. In the past, I made really rough math for 
1000-sized participants
payments pools, where for the funding_tx, you have the 1000 participants 
contributing
one input with one sig for each [0]. 

In my understanding the new limit of 2500 signatures operation would make a 
hard-limit
for the number of participants entering in such construction, without other 
tricks that
are consuming more block space. One can note the downside on funding tx of 
high-order
off-chain construction, if a max tx size consensus limit is introduced in 
the future.

Of course, I do not deny the DoS rational of introducing the 2500 sig limit 
and it's
very needed. At the same time, we should be careful of not closing too much 
doors for
future off-chain constructions and long-term tx throughput scalability.

I do believe, it's always technically possible in the future to introduce 
new opcode
or segwit versions scripts (e.g grafroot or entroot-based pool 
construction), which
wouldn't be subject to the new limit, and as such more scalable. If I'm 
correct, I
think it's all about how the limit is implemented to parse current scripts 
to be
spent.

But it's hard to say without code available to review and reason. May I 
kindly note
there is no reference implementation attached in the current BIP54 document 
[1]. Even,
if it's often updated, it's always fruitful to have code under the eyes for 
review.

This might be the kind of concern (very) far down the line...but preserving 
the
evolvability of the consensus rules is a good property to care about, in my 
humble
opinion.

Best,
Riard
OTS hash: a2bb9a1faf79309b039d8ae7e0b951644ca0adb2

[0] 
https://gnusha.org/pi/bitcoindev/CALZpt+E+eKKtOXd-8A6oThw-1i5cJ4h12TuG8tnWswqbfAnRdA@mail.gmail.com/
[1] https://github.com/bitcoin/bips/blob/master/bip-0054.md

Le mercredi 2 juillet 2025 à 09:54:33 UTC+1, Antoine Poinsot a écrit :

> Hi everyone,
>
> To mitigate high block validation time, BIP54 proposes to make 
> transactions which require more than
> 2500 legacy signature operations invalid by consensus. The 2500 figure was 
> chosen as the tightest
> value that did not make any non-pathological currently standard 
> transaction invalid.
>
> No transaction in Bitcoin's history would have both hit the BIP54 sigop 
> limit and been standard
> according to today's Bitcoin Core policy[^0]. But what happened in the 
> past doesn't matter as much
> as the fact that it is possible today to create a pathological standard 
> transaction that is
> BIP54-invalid.
>
> This opens up a major DoS vector against unupgraded miners if BIP54 ever 
> gets activated in these
> conditions. Therefore i propose to make such transactions non-standard and 
> hold off activation of
> BIP54 until we have good reasons to believe that the vast majority of the 
> hashrate won't create a
> block containing such a transaction.
>
> Doing so gives better guarantees in case BIP54 is ever considered for 
> activation, and comes at
> virtually no cost since these pathological transactions have never been 
> used and serve no purpose
> beyond increasing the cost of validation. Bitcoin Core PR #32521 
> implements this change, which i
> hope to get into the upcoming 30.0 release as well as backported to 
> previous versions.
>
> Best,
> Antoine Poinsot
>
> [^0]: Here the full list of historical transactions that would have hit 
> the BIP54 sigops limit:
> - 659135664894e50040830edb516a76f704fd2be409ecd8d1ea9916c002ab28a2
> - bea1c2b87fee95a203c5b5d9f3e5d0f472385c34cb5af02d0560aab973169683
> - 24b16a13c972522241b65fbb83d09d4bc02ceb33487f41d1f2f620b047307179
> - 53666009e036171b1aee099bc9cd3cb551969a53315410d13ad5390b8b4f3bd0
> - ffc178be118bc2f9eaf016d1c942aec18441a6c5ec17c9d92d1da7962f0479f6
> - 2f1654561297114e434c4aea5ca715e4e3f10be0be8c1c9db2b6f68ea76dae09
> - 62fc8d091a7c597783981f00b889d72d24ad5e3e224dbe1c2a317aabef89217e
> - d939315b180d3d73b5e316eb57a18f8137a3f5943aef21a811660d25f1080a3f
> - 8a6bfaa78828a81147e4848372d491aa4e9048631982a670ad3a61402a4ec327
> - 02cc78789cc070125817189ec378daa750355c8b22bbce982ed96aa549facb1f
> - b97a16ae2e8ae2a804ed7965373b42055f811653f4628e4bef999145d4b593bc
> - c51ffaf08188859669571f897f119b6d39ea48a9334212f554bf4927401b71f3
> - 33ccdda65abdda8025adb03841410dda5fa8948bd38b7fbaf3fed521daf5c4d3
> - bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08
> - ba588134ecc93fdbfa06f795c9bf7a05b09ca9ca9095659e401325d501a90363
> - ba6c6d2389f765f7873f5a9a7c11bf806afd784d15b0b8dff011fe95d1d5e841
> - dd49dc50b54b4bc1232e4b68cfdd3d349e49d3d7fe817d1041fff6dd583a6eaf
> - 3d724f03e8bcc9e2e3ea79ebe4c6cffca86d85e510742cd6d3ac29d420787a34
> - 8bcf8e8d8265922956bda9b651d2a0e993072c9dca306f3a132dcdb95c7cee6e
> - ba31c8833b7417fec9a84536f32fcb52d432acb66d99b9be6f3899686a269b2b
> - 9cc0a350d50fa252264636e62d586c7121d0a5656bc7e6b27354325684bec007
> - dd5e32971010ef0c9f4cda8977830d727a6828165c69005a3fab67415c755b7d
> - 66be4e766df2c23e08f4cf8c3e6cfa202b20967616ace38e1cbc1f20ee78db2e
> - e229a83deafec5f49e4990dba914fd815d05809f5eefbd979d55fb64f93827a3
> - 901e3695838925dd020a085e8f078c393e64179dcf0a43134a1547d21acab49a
> - 49ab4d05adbc3294fbbd63d3b876fb97a87a3f5090aa6b1d87f31ab1c4564235
> - c4f4357657ba403455167b2897acfcb922c2a0973c34e58733ca352394e6c629
> - 6c3ee29a9b584fbeae60169f0abce573a7b768bf21398d4dfad9011aa7132530
> - 5dc2bdc5ce29c52840f10203fd93ffed82da4cf49eddf93437dd1329baa9ade5
> - f40fd92f5e8cecf956caec4b6abe0b88decafde0ae71d16a72c41cb1a3da0d60
> - 92b68e4a19ef47c0dd022727a9c4b8ceb9466ce752ad8995ffbc5948bdfabf57
> - 1b604a075075197c82d33555ea48ae27e3d2724bc4c3f31650eff79692971fb7
> - 5d8875ed1707cfee2221741b3144e575aec4e0d6412eeffe1e0fa07335f61311
> - 14dd70e399f1d88efdb1c1ed799da731e3250d318bfdadc18073092aa7fd02c2
> - bb75a8d10cfbe88bb6aba7b28be497ea83f41767f4ee26217e311c615ea0132f
> - a684223716324923178a55737db81383c28f055b844d8196c988c70ee7075a9a
> - fa9120afe1bb09b7154ba82a022cbdcc29fc5be2699b346ebb7ffdc46807b2f7
> - 5e640a7861695fa660343abde52cfe10b5a97dd8fc6ad3c5e4b2b4bb1c8c3dd9
> - 7e7e69b4de5ef05750d27a863bdcb2d9dbc4a732c2a719f435ae5a9a4690b30f
> - d85ce71f583095a76fb17b5bb2a1cbf369e2a2867ca38103aa310cbb2aaf2921
> - 905df97982a2904d6d1b3dfc272435a24d705f4c7e1fc4052798b9904ad5e597
> - 5b0a05f12f33d2dc1507e5c18ceea6bb368afc51f00890965efcc3cb4025997d
> - cb550c9a1c63498f7ecb7bafc6f915318f16bb54069ff6257b4e069b97b367c8
> - 66b614e736c884c1a064f7b0d6a9b0abd97e7bb73ac7e4b1b92b493d558a0711
> - 9fdbcf0ef9d8d00f66e47917f67cc5d78aec1ac786e2abb8d2facb4e4790aad6
> - 9c667c64fcbb484b44dcce638f69130bbf1a4dd0fbb4423f58ceff92af4219ec
> - 2e7c454cfc348aa220f53b5ba21a55efa3d36353265f085e34053c4efa575fda
> - 484c8f9d1adf16a576bce52721a5e4edd5239df346d94fd730f6d7b681ab3652
> - e3d3d1ecec5d6b57792c793c413fc9b19189f5b932db8887d46f06abc101d24e
> - b23c99c30339cb93eb04790bc5213f7732365488fe2549802bb472084b6ec508
> - 92f217ec13ab309240adc0798804b3418666344a5cbfff73fb7be8192dad5261
> - 22e861ee83c3d23a4823a3786460119425d8183783068f7ec519646592fac8c2
> - fa5a58f787f569f5b8fab9dadb2447161fac45b36fb6c2c0f548ed0209b60663
> - 767885bc144bdc0414217547f0169352a065083750371cabe5acbd0e0dd60436
> - 461308024d89ea4231911df4ef24e65e60af2a9204c8282a6b67f4214c1714e7
> - 9db4e0838c55ef20c5eff271fc3bf09a404fff68f9cdad7df8eae732500b983d
> - 6e278c0ca05bf8e0317f991dae8a9efa141b5a310a4c18838b4e082e356ef649
> - 9c972a02db30f9ee91cc02b30733d70d4e2d759b5d3c73b240e5026a8a2640c4
> - d38417fcc27d3422fe05f76f6e658202d7fa394d0c9f5b419fef97610c3c49f1
> - e32477636e47e1da5fb49090a3a87a3b8ff637d069a70cd5b41595da225e65b4
> - a7e0a86944e9750a3fe372dd318da7b81c4f4c4ab228741ba0cf7fb6d56d6640
> - f62f2c6a16b5da61eaae36d30d43bb8dd8932cd89b40d83623fa185b671c67f9
> - 856a2117b6d81acbe6add60a114307d9572dff027079151d50ee77a7b0c70404
> - 763e13f873afa5f24cd33fc570a178c65e0a79c05c88c147335834fc9e8f837b
> - c3f2c2df5388b79949c01d66e83d8bc3b9ccd4f85dbd91465a16fb8e21bf8e1b
> - e245f6c3c6b02dc81ea1b6694735565cc535f603708783be027d0e6a94ac3bd5
> - 02313ac62ca8f03930cdc5d2e437fabc05aea60a31ace18a39678c90b45d32bd
> - 01d23d32bccc04b8ca5a934be16da08ae6a760ccaad2f62dc2f337eee7643517
> - d985c42bcd704aac88b9152aede1cca9bbb6baee55c8577f84c42d600cfec8e4
> - 6bb39576292c69016d0e0c1fe7871640aab12dd95874d67c46cf3424822f8dfd
> - 79e30d460594694231f163dd79a69808904819e2f39bf3e31b7ddc4baa030a04
> - 26ed04bd772c7d3d621329bda8eefec9f81108d46ef0bd3b690000465f5254b3
> - bf40393fedc45a1b347957124ef9bb8ae6a44feecee10ef2cc78064fabf8125f
> - 446c0a1d563c93285e93f085192340a82c9aef7a543d41a86b65e215794845ef
> - 1cf52f9ef89fa43bb4f042cbd4f80e9f090061e466cbe14c6b7ba525df0e572e
> - 54bf51be42ff45cdf8217b07bb233466e18d23fd66483b12449cd9b99c3a0545
> - b5ca68205e6d55e87bd6163b28467da737227c6cbcc91cb9f6dc7b400163a12b
> - 9f8cc4496cff3216608c2f2177ab360bd2d4f58cae6490d5bc23312cf30e72e0
> - 4eba5deb2bbf3abf067f524484763287911e8d68fb54fa09e1287cf6cd6d1276
> - e3de81a5817a3c825cf44fbf8185e15d446393615568966a6e3fc22cba609c7d
> - 1e700d8ce85b17d713cad1a8cae932d26740e7c8ab09d2201ddfe9d1acb4706c
> - b8ba939da1babf863746175b59cbfb3b967354f04db41bd13cb11da58e43d2a8
> - 22df2138a28c9d339813854a38181ffc5ac6f37d171d5b5bd6b0b79bf8d3c641
> - 1d93bfe18bc05b13169837b6bc868a92da3c87938531d6f3b58eee4b8822ecbf
> - e0c5e2dc3a39e733cf1bdb1a55bbcb3c2469f283becf2f99a0de771ec48f6278
> - c1e00054cc3fef88c2fdec2967e96fdb4c645bcf3f08b0580b51e47ecbfab71a
> - 9a567fde7c65bf85bbc2b109277933431ebc8a35de321a4b6436601d68aa4521
> - 6a9263e48a076bfc37deb93d01bf354305f4ac929be6b0ca05c078381a562c0c
> - 0683fb9cfcd4a211c14ef7cd2d03739160ff9ba1cb5396be227e475e932a8e9b
> - 2290263dddf8f06f099fcfb130a85f8f00b6cc1e05565a4c028d2187c8592d15
> - d27ca813c97eef5c6e9ed4bd2fe08a7e34aa8ac0c2af353826c73a4e2711a797
> - b28d67131d00bda9dac0da484dd1352c55ec6a869ea04a7e85b71d2ddf2356d9
>

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