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Use 73 bytes der-encoded signatures in weight estimation #836

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Merged
t-bast merged 3 commits into from
Nov 6, 2025
Merged

Use 73 bytes der-encoded signatures in weight estimation #836

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4817750
Use 73 bytes der-encoded signatures in weight estimation
t-bast Nov 5, 2025
3a0cc83
fixup! Use 73 bytes der-encoded signatures in weight estimation
t-bast Nov 5, 2025
c8b7b48
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t-bast Nov 5, 2025
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4 changes: 3 additions & 1 deletion modules/core/src/commonMain/kotlin/fr/acinq/lightning/transactions/Transactions.kt
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Expand Up @@ -83,7 +83,9 @@ object Transactions {
abstract val anchorAmount: Satoshi

object AnchorOutputs : CommitmentFormat() {
override val fundingInputWeight: Int = 384
// See https://github.com/lightning/bolts/blob/master/03-transactions.md#appendix-a-expected-weights
// funding input weight = 4 * funding_input_size + witness_size = 4 * 41 + 222 = 386
override val fundingInputWeight: Int = 386
override val commitWeight: Int = 1124
override val htlcOutputWeight: Int = 172
override val htlcTimeoutWeight: Int = 666
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8 changes: 4 additions & 4 deletions modules/core/src/commonTest/kotlin/fr/acinq/lightning/channel/InteractiveTxTestsCommon.kt
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Expand Up @@ -439,11 +439,11 @@ class InteractiveTxTestsCommon : LightningTestSuite() {

assertEquals(sharedTxA.sharedTx.totalAmountIn, 315_000.sat)
assertNotNull(sharedTxA.sharedTx.sharedInput)
assertEquals(sharedTxA.sharedTx.localFees, 953_000.msat)
assertEquals(sharedTxA.sharedTx.localFees, 955_000.msat)
assertEquals(sharedTxA.sharedTx.remoteFees, 357_000.msat)
assertNotNull(sharedTxB.sharedTx.sharedInput)
assertEquals(sharedTxB.sharedTx.localFees, 357_000.msat)
assertEquals(sharedTxB.sharedTx.remoteFees, 953_000.msat)
assertEquals(sharedTxB.sharedTx.remoteFees, 955_000.msat)

// Bob sends signatures first as he contributed less than Alice.
val signedTxB = sharedTxB.sharedTx.sign(bob5, f.keyManagerB, f.fundingParamsB, f.nodeIdA).right
Expand Down Expand Up @@ -670,11 +670,11 @@ class InteractiveTxTestsCommon : LightningTestSuite() {

assertEquals(sharedTxA.sharedTx.totalAmountIn, 375_000.sat)
assertNotNull(sharedTxA.sharedTx.sharedInput)
assertEquals(sharedTxA.sharedTx.localFees, 1_077_000.msat)
assertEquals(sharedTxA.sharedTx.localFees, 1_079_000.msat)
assertEquals(sharedTxA.sharedTx.remoteFees, 481_000.msat)
assertNotNull(sharedTxB.sharedTx.sharedInput)
assertEquals(sharedTxB.sharedTx.localFees, 481_000.msat)
assertEquals(sharedTxB.sharedTx.remoteFees, 1_077_000.msat)
assertEquals(sharedTxB.sharedTx.remoteFees, 1_079_000.msat)

// Bob sends signatures first as he did not contribute.
val signedTxB = sharedTxB.sharedTx.sign(bob6, f.keyManagerB, f.fundingParamsB, f.nodeIdA).right
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4 changes: 2 additions & 2 deletions ...les/core/src/commonTest/kotlin/fr/acinq/lightning/transactions/TransactionsTestsCommon.kt
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Expand Up @@ -104,8 +104,8 @@ class TransactionsTestsCommon : LightningTestSuite() {
when (commitmentFormat) {
Transactions.CommitmentFormat.AnchorOutputs -> {
// ECDSA signatures are der-encoded, which creates some variability in signature size compared to the baseline.
assertTrue(actual <= expected + 2, "actual=$actual, expected=$expected")
assertTrue(actual >= expected - 2, "actual=$actual, expected=$expected")
assertTrue(actual <= expected + 4, "actual=$actual, expected=$expected")
assertTrue(actual >= expected - 4, "actual=$actual, expected=$expected")
}
Transactions.CommitmentFormat.SimpleTaprootChannels -> assertEquals(expected, actual)
}
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