Taproot swaps

contrib/make_libsecp256k1.sh

@@ -55,6 +55,7 @@ info "Building $pkgname..."
             --enable-module-recovery \
             --enable-module-extrakeys \
             --enable-module-schnorrsig \
+            --enable-module-musig \
             --enable-experimental \
             --enable-module-ecdh \
             --disable-benchmark \

contrib/requirements/requirements.txt

@@ -6,7 +6,7 @@ aiohttp>=3.11.0,<4.0.0
 aiohttp_socks>=0.9.2
 certifi
 jsonpatch
-electrum_ecc>=0.0.4,<0.1
+electrum_ecc>=0.0.8,<0.1
 electrum_aionostr>=0.1.0,<0.2
 
 # - upper limit to avoid needing hatchling at build-time :/

electrum/bitcoin.py

@@ -793,13 +793,30 @@ def is_dummy_address(cls, addr: str) -> bool:
 class DummyAddressUsedInTxException(Exception): pass
 
 
-def taproot_tweak_pubkey(pubkey32: bytes, h: bytes) -> Tuple[int, bytes]:
+LEAF_VERSION_TAPSCRIPT = 0xC0
+
+
+def tapleaf_hash(*, leaf_version: int, script: bytes) -> bytes:
+    if not isinstance(script, bytes):
+        raise TypeError("tapleaf script must be bytes")
+    if type(leaf_version) is not int:
+        raise TypeError("tapleaf version must be an integer")
+    if not 0 <= leaf_version <= 0xFE or leaf_version & 1 or leaf_version == 0x50:
+        raise ValueError("invalid tapleaf version")
+    return bip340_tagged_hash(b"TapLeaf", bytes([leaf_version]) + witness_push(script))
+
+
+def taproot_tweak_hash(pubkey32: bytes, h: bytes) -> bytes:
     assert isinstance(pubkey32, bytes), type(pubkey32)
     assert isinstance(h, bytes), type(h)
     assert len(pubkey32) == 32, len(pubkey32)
+    return bip340_tagged_hash(b"TapTweak", pubkey32 + h)
+
+
+def taproot_tweak_pubkey(pubkey32: bytes, h: bytes) -> Tuple[int, bytes]:
     int_from_bytes = lambda x: int.from_bytes(x, byteorder="big", signed=False)
 
-    tweak = int_from_bytes(bip340_tagged_hash(b"TapTweak", pubkey32 + h))
+    tweak = int_from_bytes(taproot_tweak_hash(pubkey32, h))
     if tweak >= ecc.CURVE_ORDER:
         raise ValueError
     P = ecc.ECPubkey(b"\x02" + pubkey32)
@@ -816,7 +833,7 @@ def taproot_tweak_seckey(seckey0: bytes, h: bytes) -> bytes:
     P = ecc.ECPrivkey(seckey0)
     seckey = P.secret_scalar if P.has_even_y() else ecc.CURVE_ORDER - P.secret_scalar
     pubkey32 = P.get_public_key_bytes(compressed=True)[1:]
-    tweak = int_from_bytes(bip340_tagged_hash(b"TapTweak", pubkey32 + h))
+    tweak = int_from_bytes(taproot_tweak_hash(pubkey32, h))
     if tweak >= ecc.CURVE_ORDER:
         raise ValueError
     return int.to_bytes((seckey + tweak) % ecc.CURVE_ORDER, length=32, byteorder="big", signed=False)
@@ -832,8 +849,9 @@ def taproot_tweak_seckey(seckey0: bytes, h: bytes) -> bytes:
 def taproot_tree_helper(script_tree: TapTree):
     if isinstance(script_tree, tuple):
         leaf_version, script = script_tree
-        h = bip340_tagged_hash(b"TapLeaf", bytes([leaf_version]) + witness_push(script))
-        return [((leaf_version, script), bytes())], h
+        return [((leaf_version, script), bytes())], tapleaf_hash(
+            leaf_version=leaf_version, script=script
+        )
     left, left_h = taproot_tree_helper(script_tree[0])
     right, right_h = taproot_tree_helper(script_tree[1])
     ret = [(l, c + right_h) for l, c in left] + [(l, c + left_h) for l, c in right]

electrum/descriptor.py

@@ -32,7 +32,9 @@
 
 from .bip32 import convert_bip32_strpath_to_intpath, BIP32Node, KeyOriginInfo, BIP32_PRIME
 from . import bitcoin
-from .bitcoin import construct_script, opcodes, construct_witness, taproot_output_script
+from .bitcoin import (
+    LEAF_VERSION_TAPSCRIPT, construct_script, opcodes, construct_witness, taproot_output_script,
+)
 from . import constants
 from .crypto import hash_160, sha256
 from . import segwit_addr
@@ -808,9 +810,8 @@ def expand(self, *, pos: Optional[int] = None) -> "ExpandedScripts":
         if self.desc_tree:
             def transform(tree_node):
                 if isinstance(tree_node, Descriptor):
-                    leaf_version = 0xc0
                     leaf_script = tree_node.expand(pos=pos).scriptcode_for_sighash  # FIXME maybe rename scriptcode_for_sighash
-                    return (leaf_version, leaf_script)
+                    return (LEAF_VERSION_TAPSCRIPT, leaf_script)
                 assert len(tree_node) == 2, len(tree_node)
                 return [transform(tree_node[0]), transform(tree_node[1])]
             script_tree = transform(self.desc_tree)

electrum/plugins/swapserver/server.py

@@ -31,6 +31,7 @@
 
 from electrum.util import log_exceptions, ignore_exceptions
 from electrum.logging import Logger
+from electrum.submarine_swaps import TAPROOT_COOPERATIVE_CAPABILITY, TAPROOT_SWAP_PROTOCOL
 from electrum.util import EventListener
 
 if TYPE_CHECKING:
@@ -71,6 +72,8 @@ async def run(self):
         app.add_routes([web.post('/createswap', self.create_swap)])
         app.add_routes([web.post('/createnormalswap', self.create_normal_swap)])
         app.add_routes([web.post('/addswapinvoice', self.add_swap_invoice)])
+        app.add_routes([web.post('/claimtaprootswap', self.claim_taproot_swap)])
+        app.add_routes([web.post('/refundtaprootswap', self.refund_taproot_swap)])
 
         runner = web.AppRunner(app)
         await runner.setup()
@@ -85,6 +88,7 @@ async def get_pairs(self, r):
             "info": [],
             "warnings": [],
             "htlcFirst": True,
+            "protocols": [TAPROOT_SWAP_PROTOCOL, TAPROOT_COOPERATIVE_CAPABILITY],
             "pairs": {
                 "BTC/BTC": {
                     "rate": 1,
@@ -134,3 +138,13 @@ async def create_swap(self, r):
         request = await r.json()
         response = self.sm.server_create_swap(request)
         return web.json_response(response)
+
+    async def claim_taproot_swap(self, r):
+        request = await r.json()
+        response = self.sm.server_claim_taproot_swap(request)
+        return web.json_response(response)
+
+    async def refund_taproot_swap(self, r):
+        request = await r.json()
+        response = self.sm.server_refund_taproot_swap(request)
+        return web.json_response(response)