Use 73 bytes der-encoded signatures in weight estimation#3210
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While 73 bytes der-encoded signatures aren't standard (they're only possible with high-S signatures), miners could accept such signatures. Most of our tests use 72 bytes der-encoded signatures because we will never generate 73 bytes der-encoded signatures ourselves. But it's more safe to use a 73 bytes signature in our weight estimation because: - it's what the BOLTs recommend - it's what other implementations use (e.g. LDK) which means they may reject our interactive-tx attempts by thinking we're under-paying fees
sstone
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Nov 5, 2025
…ctions.scala Co-authored-by: Fabrice Drouin <sstone@users.noreply.github.com>
sstone
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Nov 5, 2025
|
FYI: LDK seems to be changing it the other direction: lightningdevkit/rust-lightning#4208 |
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Damn 😅, but it doesn't matter in our case since we allow the remote node to slightly underpay the estimated fees (to take into account cases where coin selection returns a solution that doesn't have a change output but slightly underpays), we won't reject splicing attempts because of this increased weight. We will slightly overpay the feerate compared to real signature size, but that's negligible. |
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While 73 bytes der-encoded signatures aren't standard (they're only possible with high-S signatures), miners could accept such signatures.
Most of our tests use 72 bytes der-encoded signatures because we will never generate 73 bytes der-encoded signatures ourselves. But it's more safe to use a 73 bytes signature in our weight estimation because: