Implement secp256k1_musig_nonce_gen_counter()

ACINQ · Sep 17, 2024 · 4203b06 · 4203b06
1 parent 5b32d69
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Showing 8 changed files with 152 additions and 14 deletions.
diff --git a/jni/c/headers/java/fr_acinq_secp256k1_Secp256k1CFunctions.h b/jni/c/headers/java/fr_acinq_secp256k1_Secp256k1CFunctions.h
diff --git a/jni/c/src/fr_acinq_secp256k1_Secp256k1CFunctions.c b/jni/c/src/fr_acinq_secp256k1_Secp256k1CFunctions.c
@@ -549,9 +549,9 @@ JNIEXPORT jbyteArray JNICALL Java_fr_acinq_secp256k1_Secp256k1CFunctions_secp256
   if (jpubkeys == NULL)
     return NULL;
 
-    count = (*penv)->GetArrayLength(penv, jpubkeys);
-    CHECKRESULT(count < 1, "pubkey array cannot be empty")
-    pubkeys = calloc(count, sizeof(secp256k1_pubkey *));
+  count = (*penv)->GetArrayLength(penv, jpubkeys);
+  CHECKRESULT(count < 1, "pubkey array cannot be empty")
+  pubkeys = calloc(count, sizeof(secp256k1_pubkey *));
 
   for (i = 0; i < count; i++)
   {
@@ -907,6 +907,80 @@ JNIEXPORT jbyteArray JNICALL Java_fr_acinq_secp256k1_Secp256k1CFunctions_secp256
   return jnonce;
 }
 
+JNIEXPORT jbyteArray JNICALL Java_fr_acinq_secp256k1_Secp256k1CFunctions_secp256k1_1musig_1nonce_1gen_1counter(JNIEnv *penv, jclass clazz, jlong jctx, jlong jcounter, jbyteArray jseckey, jbyteArray jpubkey, jbyteArray jmsg32, jbyteArray jkeyaggcache, jbyteArray jextra_input32)
+{
+  secp256k1_context *ctx = (secp256k1_context *)jctx;
+  int result = 0;
+  size_t size;
+  secp256k1_musig_pubnonce pubnonce;
+  secp256k1_musig_secnonce secnonce;
+  jbyte *pubkey_ptr;
+  secp256k1_pubkey pubkey;
+  unsigned char seckey[32];
+  unsigned char msg32[32];
+  secp256k1_musig_keyagg_cache keyaggcache;
+  unsigned char extra_input32[32];
+  jbyteArray jnonce;
+  jbyte *nonce_ptr = NULL;
+  unsigned char nonce[fr_acinq_secp256k1_Secp256k1CFunctions_SECP256K1_MUSIG_SECRET_NONCE_SIZE + fr_acinq_secp256k1_Secp256k1CFunctions_SECP256K1_MUSIG_PUBLIC_NONCE_SIZE];
+
+  if (jctx == 0)
+    return NULL;
+
+  if (jseckey == NULL)
+    return NULL;
+
+  size = (*penv)->GetArrayLength(penv, jseckey);
+  CHECKRESULT(size != 32, "invalid private key size");
+  copy_bytes_from_java(penv, jseckey, size, seckey);
+
+  if (jpubkey == NULL)
+    return NULL;
+
+  size = (*penv)->GetArrayLength(penv, jpubkey);
+  CHECKRESULT((size != 33) && (size != 65), "invalid public key size");
+  pubkey_ptr = (*penv)->GetByteArrayElements(penv, jpubkey, 0);
+  result = secp256k1_ec_pubkey_parse(ctx, &pubkey, (unsigned char *)pubkey_ptr, size);
+  (*penv)->ReleaseByteArrayElements(penv, jpubkey, pubkey_ptr, 0);
+  CHECKRESULT(!result, "secp256k1_ec_pubkey_parse failed");
+
+  if (jmsg32 != NULL)
+  {
+    size = (*penv)->GetArrayLength(penv, jmsg32);
+    CHECKRESULT(size != 32, "invalid message size");
+    copy_bytes_from_java(penv, jmsg32, size, msg32);
+  }
+
+  if (jkeyaggcache != NULL)
+  {
+    size = (*penv)->GetArrayLength(penv, jkeyaggcache);
+    CHECKRESULT(size != sizeof(secp256k1_musig_keyagg_cache), "invalid keyagg cache size");
+    copy_bytes_from_java(penv, jkeyaggcache, size, keyaggcache.data);
+  }
+
+  if (jextra_input32 != NULL)
+  {
+    size = (*penv)->GetArrayLength(penv, jextra_input32);
+    CHECKRESULT(size != 32, "invalid extra input size");
+    copy_bytes_from_java(penv, jextra_input32, size, extra_input32);
+  }
+
+  result = secp256k1_musig_nonce_gen_counter(ctx, &secnonce, &pubnonce, jcounter,
+                                             seckey, &pubkey,
+                                             jmsg32 == NULL ? NULL : msg32, jkeyaggcache == NULL ? NULL : &keyaggcache, jextra_input32 == NULL ? NULL : extra_input32);
+  CHECKRESULT(!result, "secp256k1_musig_nonce_gen failed");
+
+  memcpy(nonce, secnonce.data, fr_acinq_secp256k1_Secp256k1CFunctions_SECP256K1_MUSIG_SECRET_NONCE_SIZE);
+  result = secp256k1_musig_pubnonce_serialize(ctx, nonce + fr_acinq_secp256k1_Secp256k1CFunctions_SECP256K1_MUSIG_SECRET_NONCE_SIZE, &pubnonce);
+  CHECKRESULT(!result, "secp256k1_musig_pubnonce_serialize failed");
+
+  jnonce = (*penv)->NewByteArray(penv, sizeof(nonce));
+  nonce_ptr = (*penv)->GetByteArrayElements(penv, jnonce, 0);
+  memcpy(nonce_ptr, nonce, sizeof(nonce));
+  (*penv)->ReleaseByteArrayElements(penv, jnonce, nonce_ptr, 0);
+  return jnonce;
+}
+
 void free_nonces(secp256k1_musig_pubnonce **nonces, size_t count)
 {
   size_t i;

diff --git a/jni/src/main/java/fr/acinq/secp256k1/Secp256k1CFunctions.java b/jni/src/main/java/fr/acinq/secp256k1/Secp256k1CFunctions.java
@@ -89,7 +89,9 @@ public class Secp256k1CFunctions {
 
     public static native int secp256k1_schnorrsig_verify(long ctx, byte[] sig, byte[] msg, byte[] pubkey);
 
-    public static native byte[] secp256k1_musig_nonce_gen(long ctx, byte[] session_id32, byte[] seckey, byte[] pubkey, byte[] msg32, byte[] keyagg_cache, byte[] extra_input32);
+    public static native byte[] secp256k1_musig_nonce_gen(long ctx, byte[] session_rand32, byte[] seckey, byte[] pubkey, byte[] msg32, byte[] keyagg_cache, byte[] extra_input32);
+
+    public static native byte[] secp256k1_musig_nonce_gen_counter(long ctx, long nonrepeating_cnt, byte[] seckey, byte[] pubkey, byte[] msg32, byte[] keyagg_cache, byte[] extra_input32);
 
     public static native byte[] secp256k1_musig_nonce_agg(long ctx, byte[][] nonces);
 

diff --git a/jni/src/main/kotlin/fr/acinq/secp256k1/NativeSecp256k1.kt b/jni/src/main/kotlin/fr/acinq/secp256k1/NativeSecp256k1.kt
@@ -92,8 +92,12 @@ public object NativeSecp256k1 : Secp256k1 {
         return Secp256k1CFunctions.secp256k1_schnorrsig_sign(Secp256k1Context.getContext(), data, sec, auxrand32)
     }
 
-    override fun musigNonceGen(sessionId32: ByteArray, privkey: ByteArray?, aggpubkey: ByteArray, msg32: ByteArray?, keyaggCache: ByteArray?, extraInput32: ByteArray?): ByteArray {
-        return Secp256k1CFunctions.secp256k1_musig_nonce_gen(Secp256k1Context.getContext(), sessionId32, privkey, aggpubkey, msg32, keyaggCache, extraInput32)
+    override fun musigNonceGen(sessionRandom32: ByteArray, privkey: ByteArray?, pubkey: ByteArray, msg32: ByteArray?, keyaggCache: ByteArray?, extraInput32: ByteArray?): ByteArray {
+        return Secp256k1CFunctions.secp256k1_musig_nonce_gen(Secp256k1Context.getContext(), sessionRandom32, privkey, pubkey, msg32, keyaggCache, extraInput32)
+    }
+
+    override fun musigNonceGenCounter(nonRepeatingCounter: ULong, privkey: ByteArray, pubkey: ByteArray, msg32: ByteArray?, keyaggCache: ByteArray?, extraInput32: ByteArray?): ByteArray {
+        return Secp256k1CFunctions.secp256k1_musig_nonce_gen_counter(Secp256k1Context.getContext(), nonRepeatingCounter.toLong(), privkey, pubkey, msg32, keyaggCache, extraInput32)
     }
 
     override fun musigNonceAgg(pubnonces: Array<ByteArray>): ByteArray {

diff --git a/native/secp256k1 b/native/secp256k1
diff --git a/src/commonMain/kotlin/fr/acinq/secp256k1/Secp256k1.kt b/src/commonMain/kotlin/fr/acinq/secp256k1/Secp256k1.kt
@@ -159,15 +159,30 @@ public interface Secp256k1 {
      * This nonce must never be persisted or reused across signing sessions.
      * All optional arguments exist to enrich the quality of the randomness used, which is critical for security.
      *
-     * @param sessionId32 unique 32-byte session ID.
+     * @param sessionRandom32 unique 32-byte random data that must not be reused to generate other nonces
      * @param privkey (optional) signer's private key.
-     * @param aggpubkey aggregated public key of all participants in the signing session.
+     * @param pubkey signer's public key
      * @param msg32 (optional) 32-byte message that will be signed, if already known.
      * @param keyaggCache (optional) key aggregation cache data from the signing session.
      * @param extraInput32 (optional) additional 32-byte random data.
      * @return serialized version of the secret nonce and the corresponding public nonce.
      */
-    public fun musigNonceGen(sessionId32: ByteArray, privkey: ByteArray?, aggpubkey: ByteArray, msg32: ByteArray?, keyaggCache: ByteArray?, extraInput32: ByteArray?): ByteArray
+    public fun musigNonceGen(sessionRandom32: ByteArray, privkey: ByteArray?, pubkey: ByteArray, msg32: ByteArray?, keyaggCache: ByteArray?, extraInput32: ByteArray?): ByteArray
+
+    /**
+     * Alternative counter-based method for generating nonce.
+     * This nonce must never be persisted or reused across signing sessions.
+     * All optional arguments exist to enrich the quality of the randomness used, which is critical for security.
+     *
+     * @param nonRepeatingCounter non-repeating counter that must never be reused with the same private key
+     * @param privkey signer's private key.
+     * @param pubkey signer's public key
+     * @param msg32 (optional) 32-byte message that will be signed, if already known.
+     * @param keyaggCache (optional) key aggregation cache data from the signing session.
+     * @param extraInput32 (optional) additional 32-byte random data.
+     * @return serialized version of the secret nonce and the corresponding public nonce.
+     */
+    public fun musigNonceGenCounter(nonRepeatingCounter: ULong, privkey: ByteArray, pubkey: ByteArray, msg32: ByteArray?, keyaggCache: ByteArray?, extraInput32: ByteArray?): ByteArray
 
     /**
      * Aggregate public nonces from all participants of a signing session.

diff --git a/src/nativeMain/kotlin/fr/acinq/secp256k1/Secp256k1Native.kt b/src/nativeMain/kotlin/fr/acinq/secp256k1/Secp256k1Native.kt
@@ -3,6 +3,7 @@ package fr.acinq.secp256k1
 import kotlinx.cinterop.*
 import platform.posix.memcpy
 import platform.posix.size_tVar
+import platform.posix.uint64_t
 import secp256k1.*
 
 @OptIn(ExperimentalUnsignedTypes::class, ExperimentalForeignApi::class)
@@ -291,8 +292,8 @@ public object Secp256k1Native : Secp256k1 {
         }
     }
 
-    override fun musigNonceGen(sessionId32: ByteArray, privkey: ByteArray?, aggpubkey: ByteArray, msg32: ByteArray?, keyaggCache: ByteArray?, extraInput32: ByteArray?): ByteArray {
-        require(sessionId32.size == 32)
+    override fun musigNonceGen(sessionRandom32: ByteArray, privkey: ByteArray?, pubkey: ByteArray, msg32: ByteArray?, keyaggCache: ByteArray?, extraInput32: ByteArray?): ByteArray {
+        require(sessionRandom32.size == 32)
         privkey?.let { require(it.size == 32) }
         msg32?.let { require(it.size == 32) }
         keyaggCache?.let { require(it.size == Secp256k1.MUSIG2_PUBLIC_KEYAGG_CACHE_SIZE) }
@@ -301,7 +302,7 @@ public object Secp256k1Native : Secp256k1 {
         val nonce = memScoped {
             val secnonce = alloc<secp256k1_musig_secnonce>()
             val pubnonce = alloc<secp256k1_musig_pubnonce>()
-            val nPubkey = allocPublicKey(aggpubkey)
+            val nPubkey = allocPublicKey(pubkey)
             val nKeyAggCache = keyaggCache?.let {
                 val n = alloc<secp256k1_musig_keyagg_cache>()
                 memcpy(n.ptr, toNat(it), Secp256k1.MUSIG2_PUBLIC_KEYAGG_CACHE_SIZE.toULong())
@@ -311,7 +312,7 @@ public object Secp256k1Native : Secp256k1 {
                 ctx,
                 secnonce.ptr,
                 pubnonce.ptr,
-                toNat(sessionId32),
+                toNat(sessionRandom32),
                 privkey?.let { toNat(it) },
                 nPubkey.ptr,
                 msg32?.let { toNat(it) },
@@ -324,6 +325,29 @@ public object Secp256k1Native : Secp256k1 {
         return nonce
     }
 
+    override fun musigNonceGenCounter(nonRepeatingCounter: ULong, privkey: ByteArray, pubkey: ByteArray, msg32: ByteArray?, keyaggCache: ByteArray?, extraInput32: ByteArray?): ByteArray {
+        require(privkey.size ==32)
+        require(pubkey.size == 33 || pubkey.size == 65)
+        msg32?.let { require(it.size == 32) }
+        keyaggCache?.let { require(it.size == Secp256k1.MUSIG2_PUBLIC_KEYAGG_CACHE_SIZE) }
+        extraInput32?.let { require(it.size == 32) }
+        val nonce = memScoped {
+            val secnonce = alloc<secp256k1_musig_secnonce>()
+            val pubnonce = alloc<secp256k1_musig_pubnonce>()
+            val nPubkey = allocPublicKey(pubkey)
+            val nKeyAggCache = keyaggCache?.let {
+                val n = alloc<secp256k1_musig_keyagg_cache>()
+                memcpy(n.ptr, toNat(it), Secp256k1.MUSIG2_PUBLIC_KEYAGG_CACHE_SIZE.toULong())
+                n
+            }
+            secp256k1_musig_nonce_gen_counter(ctx, secnonce.ptr, pubnonce.ptr, nonRepeatingCounter, toNat(privkey), nPubkey.ptr, msg32?.let { toNat(it) },nKeyAggCache?.ptr, extraInput32?.let { toNat(it) }).requireSuccess("secp256k1_musig_nonce_gen_counter() 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)
+        }
+        return nonce
+    }
+
     override fun musigNonceAgg(pubnonces: Array<ByteArray>): ByteArray {
         require(pubnonces.isNotEmpty())
         pubnonces.forEach { require(it.size == Secp256k1.MUSIG2_PUBLIC_NONCE_SIZE) }

diff --git a/tests/src/commonTest/kotlin/fr/acinq/secp256k1/Musig2Test.kt b/tests/src/commonTest/kotlin/fr/acinq/secp256k1/Musig2Test.kt
@@ -108,6 +108,17 @@ class Musig2Test {
         }
     }
 
+    @Test
+    fun `generate secret nonce from counter`() {
+        val sk = Hex.decode("EEC1CB7D1B7254C5CAB0D9C61AB02E643D464A59FE6C96A7EFE871F07C5AEF54")
+        val pk = Secp256k1.pubkeyCreate(sk)
+        val nonce = Secp256k1.musigNonceGenCounter(0UL, sk, pk, null, null, null)
+        val secnonce = nonce.copyOfRange(0, Secp256k1.MUSIG2_SECRET_NONCE_SIZE)
+        val pubnonce = nonce.copyOfRange(Secp256k1.MUSIG2_SECRET_NONCE_SIZE, Secp256k1.MUSIG2_SECRET_NONCE_SIZE + Secp256k1.MUSIG2_PUBLIC_NONCE_SIZE)
+        assertContentEquals(secnonce.copyOfRange(4, 4 + 64), Hex.decode("842F1380CD17A198FC3DAD3B7DA7492941F46976F2702FF7C66F24F472036AF1DA3F952DDE4A2DA6B6325707CE87A4E3616D06FC5F81A9C99386D20A99CECF99"))
+        assertContentEquals(pubnonce, Hex.decode("03A5B9B6907942EACDDA49A366016EC2E62404A1BF4AB6D4DB82067BC3ADF086D7033205DB9EB34D5C7CE02848CAC68A83ED73E3883477F563F23CE9A11A7721EC64"))
+    }
+
     @Test
     fun `aggregate nonces`() {
         val tests = readData("musig2/nonce_agg_vectors.json")