Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Verify musig2 secret nonces #108

Merged
merged 5 commits into from
Apr 18, 2024
Merged

Verify musig2 secret nonces #108

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
e532ad8
Verify musig2 secret nonces
sstone Apr 16, 2024
2732f67
Address review comments
sstone Apr 17, 2024
3404542
Fixup! remove empty line
sstone Apr 17, 2024
a1ddfde
fixup! Address review comments
sstone Apr 17, 2024
384cdc2
Print musig2 test data whenever a test fails
sstone Apr 17, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions jni/src/main/kotlin/fr/acinq/secp256k1/NativeSecp256k1.kt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,7 @@ public object NativeSecp256k1 : Secp256k1 {
}

override fun musigPartialSign(secnonce: ByteArray, privkey: ByteArray, keyaggCache: ByteArray, session: ByteArray): ByteArray {
require(musigNonceValidate(secnonce, pubkeyCreate(privkey)))
return Secp256k1CFunctions.secp256k1_musig_partial_sign(Secp256k1Context.getContext(), secnonce, privkey, keyaggCache, session)
}

Expand Down
20 changes: 20 additions & 0 deletions src/commonMain/kotlin/fr/acinq/secp256k1/Secp256k1.kt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -217,6 +217,26 @@ public interface Secp256k1 {
*/
public fun musigNonceProcess(aggnonce: ByteArray, msg32: ByteArray, keyaggCache: ByteArray): ByteArray

/**
* Check that a secret nonce was generated with a public key that matches the private key used for signing.
* @param secretnonce secret nonce.
* @param pubkey public key for the private key that will be used, with the secret nonce, to generate a partial signature.
* @return false if the secret nonce does not match the public key.
*/
public fun musigNonceValidate(secretnonce: ByteArray, pubkey: ByteArray): Boolean {
if (secretnonce.size != MUSIG2_SECRET_NONCE_SIZE) return false
if (pubkey.size != 33 && pubkey.size != 65) return false
val pk = Secp256k1.pubkeyParse(pubkey)
// this is a bit hackish but the secp256k1 library does not export methods to do this cleanly
val x = secretnonce.copyOfRange(68, 68 + 32)
x.reverse()
val y = secretnonce.copyOfRange(68 + 32, 68 + 32 + 32)
y.reverse()
val pkx = pk.copyOfRange(1, 1 + 32)
val pky = pk.copyOfRange(33, 33 + 32)
return x.contentEquals(pkx) && y.contentEquals(pky)
}

/**
* Create a partial signature.
*
Expand Down
20 changes: 15 additions & 5 deletions src/nativeMain/kotlin/fr/acinq/secp256k1/Secp256k1Native.kt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -81,7 +81,7 @@ public object Secp256k1Native : Secp256k1 {
return serialized.readBytes(Secp256k1.MUSIG2_PUBLIC_NONCE_SIZE)
}

private fun DeferScope.toNat(bytes: ByteArray): CPointer<UByteVar> {
private fun DeferScope.toNat(bytes: ByteArray): CPointer<UByteVar> {
val ubytes = bytes.asUByteArray()
val pinned = ubytes.pin()
this.defer { pinned.unpin() }
Expand Down Expand Up @@ -112,7 +112,7 @@ public object Secp256k1Native : Secp256k1 {
}

public override fun signatureNormalize(sig: ByteArray): Pair<ByteArray, Boolean> {
require(sig.size >= 64){ "invalid signature ${Hex.encode(sig)}" }
require(sig.size >= 64) { "invalid signature ${Hex.encode(sig)}" }
memScoped {
val nSig = allocSignature(sig)
val isHighS = secp256k1_ecdsa_signature_normalize(ctx, nSig.ptr, nSig.ptr)
Expand Down Expand Up @@ -307,7 +307,16 @@ public object Secp256k1Native : Secp256k1 {
memcpy(n.ptr, toNat(it), Secp256k1.MUSIG2_PUBLIC_KEYAGG_CACHE_SIZE.toULong())
n
}
secp256k1_musig_nonce_gen(ctx, secnonce.ptr, pubnonce.ptr, toNat(sessionId32), privkey?.let { toNat(it) }, nPubkey.ptr, msg32?.let { toNat(it) },nKeyAggCache?.ptr, extraInput32?.let { toNat(it) }).requireSuccess("secp256k1_musig_nonce_gen() failed")
secp256k1_musig_nonce_gen(
ctx,
secnonce.ptr,
pubnonce.ptr,
toNat(sessionId32),
privkey?.let { toNat(it) },
nPubkey.ptr,
msg32?.let { toNat(it) },
nKeyAggCache?.ptr,
extraInput32?.let { toNat(it) }).requireSuccess("secp256k1_musig_nonce_gen() failed")
val nPubnonce = allocArray<UByteVar>(Secp256k1.MUSIG2_PUBLIC_NONCE_SIZE)
secp256k1_musig_pubnonce_serialize(ctx, nPubnonce, pubnonce.ptr).requireSuccess("secp256k1_musig_pubnonce_serialize failed")
secnonce.ptr.readBytes(Secp256k1.MUSIG2_SECRET_NONCE_SIZE) + nPubnonce.readBytes(Secp256k1.MUSIG2_PUBLIC_NONCE_SIZE)
Expand Down Expand Up @@ -339,7 +348,7 @@ public object Secp256k1Native : Secp256k1 {
n
}
secp256k1_musig_pubkey_agg(ctx, combined.ptr, nKeyAggCache?.ptr, nPubkeys.toCValues(), pubkeys.size.convert()).requireSuccess("secp256k1_musig_nonce_agg() failed")
val agg = serializeXonlyPubkey(combined)
val agg = serializeXonlyPubkey(combined)
keyaggCache?.let { blob -> nKeyAggCache?.let { memcpy(toNat(blob), it.ptr, Secp256k1.MUSIG2_PUBLIC_KEYAGG_CACHE_SIZE.toULong()) } }
return agg
}
Expand Down Expand Up @@ -386,13 +395,14 @@ public object Secp256k1Native : Secp256k1 {
memcpy(toNat(session), nSession.ptr, Secp256k1.MUSIG2_PUBLIC_SESSION_SIZE.toULong())
return session
}
}
}

override fun musigPartialSign(secnonce: ByteArray, privkey: ByteArray, keyaggCache: ByteArray, session: ByteArray): ByteArray {
require(secnonce.size == Secp256k1.MUSIG2_SECRET_NONCE_SIZE)
require(privkey.size == 32)
require(keyaggCache.size == Secp256k1.MUSIG2_PUBLIC_KEYAGG_CACHE_SIZE)
require(session.size == Secp256k1.MUSIG2_PUBLIC_SESSION_SIZE)
require(musigNonceValidate(secnonce, pubkeyCreate(privkey)))

memScoped {
val nSecnonce = alloc<secp256k1_musig_secnonce>()
Expand Down
66 changes: 44 additions & 22 deletions tests/src/commonTest/kotlin/fr/acinq/secp256k1/Secp256k1Test.kt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,14 @@ import kotlin.test.*

class Secp256k1Test {

val random = Random.Default

fun randomBytes(length: Int): ByteArray {
val buffer = ByteArray(length)
random.nextBytes(buffer)
return buffer
}

@Test
fun verifyValidPrivateKey() {
val priv = Hex.decode("67E56582298859DDAE725F972992A07C6C4FB9F62A8FFF58CE3CA926A1063530".lowercase())
Expand Down Expand Up @@ -454,40 +462,55 @@ class Secp256k1Test {

@Test
fun testMusig2SigningSession() {
val privkeys = listOf(
"0101010101010101010101010101010101010101010101010101010101010101",
"0202020202020202020202020202020202020202020202020202020202020202",
).map { Hex.decode(it) }.toTypedArray()
val privkeys = listOf(randomBytes(32), randomBytes(32))
val sessionId = randomBytes(32)
val msg32 = randomBytes(32)
val pubkeys = privkeys.map { Secp256k1.pubkeyCreate(it) }

val sessionId = Hex.decode("0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F")
val nonces = pubkeys.map { Secp256k1.musigNonceGen(sessionId, null, it, null, null, null) }
val testData = run {
val builder = StringBuilder()
builder.append("private keys\n")
privkeys.forEach { builder.append(Hex.encode(it)).append("\n") }
builder.append("sessionId ${Hex.encode(sessionId)}\n")
builder.append("msg32 ${Hex.encode(msg32)}\n")
builder.append("nonces\n")
nonces.forEach { builder.append(Hex.encode(it)).append("\n") }
builder.toString()
}
val secnonces = nonces.map { it.copyOfRange(0, 132) }
val pubnonces = nonces.map { it.copyOfRange(132, 132 + 66) }
val aggnonce = Secp256k1.musigNonceAgg(pubnonces.toTypedArray())

val keyaggCaches = (0 until 2).map { ByteArray(Secp256k1.MUSIG2_PUBLIC_KEYAGG_CACHE_SIZE) }
val aggpubkey = Secp256k1.musigPubkeyAgg(pubkeys.toTypedArray(), keyaggCaches[0])
assertContentEquals(aggpubkey, Secp256k1.musigPubkeyAgg(pubkeys.toTypedArray(), keyaggCaches[1]))
assertContentEquals(keyaggCaches[0], keyaggCaches[1])
assertContentEquals(aggpubkey, Secp256k1.musigPubkeyAgg(pubkeys.toTypedArray(), keyaggCaches[1]), testData)
assertContentEquals(keyaggCaches[0], keyaggCaches[1], testData)

val msg32 = Hex.decode("0303030303030303030303030303030303030303030303030303030303030303")
val sessions = (0 until 2).map { Secp256k1.musigNonceProcess(aggnonce, msg32, keyaggCaches[it]) }
val psigs = (0 until 2).map {
val psig = Secp256k1.musigPartialSign(secnonces[it], privkeys[it], keyaggCaches[it], sessions[it])
assertEquals(1, Secp256k1.musigPartialSigVerify(psig, pubnonces[it], pubkeys[it], keyaggCaches[it], sessions[it]))
assertEquals(0, Secp256k1.musigPartialSigVerify(Random.nextBytes(32), pubnonces[it], pubkeys[it], keyaggCaches[it], sessions[it]))
assertEquals(1, Secp256k1.musigPartialSigVerify(psig, pubnonces[it], pubkeys[it], keyaggCaches[it], sessions[it]), testData)
assertEquals(0, Secp256k1.musigPartialSigVerify(Random.nextBytes(32), pubnonces[it], pubkeys[it], keyaggCaches[it], sessions[it]), testData)
psig
}

// signing fails if the secret nonce does not match the private key's public key
assertFails(testData) {
Secp256k1.musigPartialSign(secnonces[1], privkeys[0], keyaggCaches[0], sessions[0])
}

assertFails(testData) {
Secp256k1.musigPartialSign(secnonces[0], privkeys[1], keyaggCaches[1], sessions[1])
}

val sig = Secp256k1.musigPartialSigAgg(sessions[0], psigs.toTypedArray())
assertContentEquals(sig, Secp256k1.musigPartialSigAgg(sessions[1], psigs.toTypedArray()))
assertTrue(Secp256k1.verifySchnorr(sig, msg32, aggpubkey))
assertContentEquals(sig, Secp256k1.musigPartialSigAgg(sessions[1], psigs.toTypedArray()), testData)
assertTrue(Secp256k1.verifySchnorr(sig, msg32, aggpubkey), testData)

val invalidSig1 = Secp256k1.musigPartialSigAgg(sessions[0], arrayOf(psigs[0], psigs[0]))
assertFalse(Secp256k1.verifySchnorr(invalidSig1, msg32, aggpubkey))
assertFalse(Secp256k1.verifySchnorr(invalidSig1, msg32, aggpubkey), testData)
val invalidSig2 = Secp256k1.musigPartialSigAgg(sessions[0], arrayOf(Random.nextBytes(32), Random.nextBytes(32)))
assertFalse(Secp256k1.verifySchnorr(invalidSig2, msg32, aggpubkey))
assertFalse(Secp256k1.verifySchnorr(invalidSig2, msg32, aggpubkey), testData)
}

@Test
Expand Down Expand Up @@ -523,15 +546,14 @@ class Secp256k1Test {
}

@Test
fun fuzzEcdsaSignVerify() {
val random = Random.Default

fun randomBytes(length: Int): ByteArray {
val buffer = ByteArray(length)
random.nextBytes(buffer)
return buffer
fun fuzzMusig2SigningSession() {
t-bast marked this conversation as resolved.
Show resolved Hide resolved
repeat(1000) {
testMusig2SigningSession()
}
}

@Test
fun fuzzEcdsaSignVerify() {
repeat(200) {
val priv = randomBytes(32)
assertTrue(Secp256k1.secKeyVerify(priv))
Expand Down
Loading