Namecoin / AuxPoW: Truncate AuxPoW when covered by a checkpoint

electrum/blockchain.py

@@ -68,7 +68,7 @@ def deserialize_header(s: bytes, height: int, expect_trailing_data=False, start_
     h['nonce'] = hex_to_int(s[start_position+76:start_position+80])
     h['block_height'] = height
 
-    if auxpow.auxpow_active(h):
+    if auxpow.auxpow_active(h) and height > constants.net.max_checkpoint():
         if expect_trailing_data:
             h['auxpow'], start_position = auxpow.deserialize_auxpow_header(h, s, expect_trailing_data=True, start_position=start_position+HEADER_SIZE)
         else:
@@ -271,7 +271,9 @@ def update_size(self) -> None:
     @classmethod
     def verify_header(cls, header: dict, prev_hash: str, target: int, expected_header_hash: str=None) -> None:
         _hash = hash_header(header)
-        _pow_hash = auxpow.hash_parent_header(header)
+        # Don't verify AuxPoW when covered by a checkpoint
+        if header.get('block_height') > constants.net.max_checkpoint():
+            _pow_hash = auxpow.hash_parent_header(header)
         if expected_header_hash and expected_header_hash != _hash:
             raise Exception("hash mismatches with expected: {} vs {}".format(expected_header_hash, _hash))
         if prev_hash != header.get('prev_block_hash'):
@@ -281,9 +283,11 @@ def verify_header(cls, header: dict, prev_hash: str, target: int, expected_heade
         bits = cls.target_to_bits(target)
         if bits != header.get('bits'):
             raise Exception("bits mismatch: %s vs %s" % (bits, header.get('bits')))
-        block_hash_as_num = int.from_bytes(bfh(_pow_hash), byteorder='big')
-        if block_hash_as_num > target:
-            raise Exception(f"insufficient proof of work: {block_hash_as_num} vs target {target}")
+        # Don't verify AuxPoW when covered by a checkpoint
+        if header.get('block_height') > constants.net.max_checkpoint():
+            block_hash_as_num = int.from_bytes(bfh(_pow_hash), byteorder='big')
+            if block_hash_as_num > target:
+                raise Exception(f"insufficient proof of work: {block_hash_as_num} vs target {target}")
 
     def verify_chunk(self, index: int, data: bytes) -> bytes:
         stripped = bytearray()

electrum/interface.py

@@ -348,7 +348,12 @@ async def get_block_header(self, height, assert_mode):
         self.print_error('requesting block header {} in mode {}'.format(height, assert_mode))
         # use lower timeout as we usually have network.bhi_lock here
         timeout = self.network.get_network_timeout_seconds(NetworkTimeout.Urgent)
-        res = await self.session.send_request('blockchain.block.header', [height], timeout=timeout)
+        cp_height = constants.net.max_checkpoint()
+        if height > cp_height:
+            cp_height = 0
+        res = await self.session.send_request('blockchain.block.header', [height, cp_height], timeout=timeout)
+        if cp_height != 0:
+            res = res["header"]
         return blockchain.deserialize_header(bytes.fromhex(res), height)
 
     async def request_chunk(self, height, tip=None, *, can_return_early=False):
@@ -361,8 +366,11 @@ async def request_chunk(self, height, tip=None, *, can_return_early=False):
             size = min(size, tip - index * 2016 + 1)
             size = max(size, 0)
         try:
+            cp_height = constants.net.max_checkpoint()
+            if index * 2016 + size - 1 > cp_height:
+                cp_height = 0
             self._requested_chunks.add(index)
-            res = await self.session.send_request('blockchain.block.headers', [index * 2016, size])
+            res = await self.session.send_request('blockchain.block.headers', [index * 2016, size, cp_height])
         finally:
             try: self._requested_chunks.remove(index)
             except KeyError: pass

electrum/version.py

@@ -1,7 +1,7 @@
 ELECTRUM_VERSION = '3.3.2'   # version of the client package
 APK_VERSION = '3.3.2.0'      # read by buildozer.spec
 
-PROTOCOL_VERSION = '1.4'     # protocol version requested
+PROTOCOL_VERSION = '1.4.1'     # protocol version requested
 
 # The hash of the mnemonic seed must begin with this
 SEED_PREFIX        = '01'      # Standard wallet