ln: use START_INDEX instead of 2**48-1

electrum/lnbase.py

@@ -530,7 +530,7 @@ class Peer(PrintError):
         )
         # TODO derive this?
         per_commitment_secret_seed = 0x1f1e1d1c1b1a191817161514131211100f0e0d0c0b0a09080706050403020100.to_bytes(32, 'big')
-        per_commitment_secret_index = 2**48 - 1
+        per_commitment_secret_index = RevocationStore.START_INDEX
         # for the first commitment transaction
         per_commitment_secret_first = get_per_commitment_secret_from_seed(per_commitment_secret_seed, per_commitment_secret_index)
         per_commitment_point_first = secret_to_pubkey(int.from_bytes(per_commitment_secret_first, 'big'))
@@ -680,7 +680,7 @@ class Peer(PrintError):
 
     def funding_locked(self, chan):
         channel_id = chan.channel_id
-        per_commitment_secret_index = 2**48 - 2
+        per_commitment_secret_index = RevocationStore.START_INDEX - 1
         per_commitment_point_second = secret_to_pubkey(int.from_bytes(
             get_per_commitment_secret_from_seed(chan.local_state.per_commitment_secret_seed, per_commitment_secret_index), 'big'))
         self.send_message(gen_msg("funding_locked", channel_id=channel_id, next_per_commitment_point=per_commitment_point_second))

electrum/tests/test_lnhtlc.py

@@ -91,10 +91,10 @@ def create_test_channels(feerate=6000, local=None, remote=None):
     alice_seed = os.urandom(32)
     bob_seed = os.urandom(32)
 
-    alice_cur = lnutil.secret_to_pubkey(int.from_bytes(lnutil.get_per_commitment_secret_from_seed(alice_seed, 2**48 - 1), "big"))
-    alice_next = lnutil.secret_to_pubkey(int.from_bytes(lnutil.get_per_commitment_secret_from_seed(alice_seed, 2**48 - 2), "big"))
-    bob_cur = lnutil.secret_to_pubkey(int.from_bytes(lnutil.get_per_commitment_secret_from_seed(bob_seed, 2**48 - 1), "big"))
-    bob_next = lnutil.secret_to_pubkey(int.from_bytes(lnutil.get_per_commitment_secret_from_seed(bob_seed, 2**48 - 2), "big"))
+    alice_cur = lnutil.secret_to_pubkey(int.from_bytes(lnutil.get_per_commitment_secret_from_seed(alice_seed, lnutil.RevocationStore.START_INDEX), "big"))
+    alice_next = lnutil.secret_to_pubkey(int.from_bytes(lnutil.get_per_commitment_secret_from_seed(alice_seed, lnutil.RevocationStore.START_INDEX - 1), "big"))
+    bob_cur = lnutil.secret_to_pubkey(int.from_bytes(lnutil.get_per_commitment_secret_from_seed(bob_seed, lnutil.RevocationStore.START_INDEX), "big"))
+    bob_next = lnutil.secret_to_pubkey(int.from_bytes(lnutil.get_per_commitment_secret_from_seed(bob_seed, lnutil.RevocationStore.START_INDEX - 1), "big"))
 
     return \
         lnhtlc.HTLCStateMachine(

electrum/tests/test_lnutil.py

@@ -440,7 +440,7 @@ class TestLNUtil(unittest.TestCase):
         seed = bitcoin.sha256(b"shachaintest")
         consumer = RevocationStore()
         for i in range(10000):
-            secret = get_per_commitment_secret_from_seed(seed, 2**48 - i - 1)
+            secret = get_per_commitment_secret_from_seed(seed, RevocationStore.START_INDEX - i)
             try:
                 consumer.add_next_entry(secret)
             except Exception as e: