get_per_commitment_secret_from_seed (not working yet)

lib/lnbase.py

@@ -316,6 +316,35 @@ def derive_blinded_pubkey(basepoint, per_commitment_point):
     k2 = ser_to_point(per_commitment_point) * bitcoin.string_to_number(bitcoin.sha256(per_commitment_point + basepoint))
     return point_to_ser(k1 + k2)
 
+
+def get_per_commitment_secret_from_seed(seed: int, i: int) -> int:
+    """Generate per commitment secret."""
+
+
+    #seed ^= 1
+    #pcs_bytes = seed.to_bytes(byteorder="big", length=32)
+    #print(bh2u(pcs_bytes))
+    #return int.from_bytes(hashlib.sha256(pcs_bytes[::-1]).digest(), byteorder="big")
+
+    #tmp = seed.to_bytes(byteorder="big", length=32)
+    #seed = int.from_bytes(tmp[::-1], byteorder="big")
+
+    per_commitment_secret = seed
+    print('get_per_commitment_secret_from_seed() per_commitment_secret', per_commitment_secret)
+    print('get_per_commitment_secret_from_seed() i', i)
+    for bitindex in range(47, -1, -1):  # 47, 46, ..., 0
+        mask = 1 << bitindex
+        if i & mask:
+            print('get_per_commitment_secret_from_seed() bitindex, mask', bitindex, mask)
+            print('get_per_commitment_secret_from_seed() branch entered')
+            per_commitment_secret ^= mask
+            print('get_per_commitment_secret_from_seed() per_commitment_secret br1', per_commitment_secret)
+            pcs_bytes = per_commitment_secret.to_bytes(byteorder="big", length=32)
+            per_commitment_secret = int.from_bytes(bitcoin.sha256(pcs_bytes[::-1]), byteorder="big")
+            print('get_per_commitment_secret_from_seed() per_commitment_secret br2', per_commitment_secret)
+    return per_commitment_secret
+
+
 def overall_weight(num_htlc):
     return 500 + 172 * num_htlc + 224
 

lib/tests/test_lnbase.py

@@ -5,7 +5,7 @@ import unittest
 from lib.util import bh2u, bfh
 from lib.lnbase import make_commitment, get_obscured_ctn, Peer, make_offered_htlc, make_received_htlc, make_htlc_tx
 from lib.lnbase import secret_to_pubkey, derive_pubkey, derive_privkey, derive_blinded_pubkey, overall_weight
-from lib.lnbase import make_htlc_tx_output, make_htlc_tx_inputs
+from lib.lnbase import make_htlc_tx_output, make_htlc_tx_inputs, get_per_commitment_secret_from_seed
 from lib.transaction import Transaction
 from lib import bitcoin
 import ecdsa.ellipticcurve
@@ -231,3 +231,17 @@ class Test_LNBase(unittest.TestCase):
         self.assertEqual(revocation_basepoint, bfh('036d6caac248af96f6afa7f904f550253a0f3ef3f5aa2fe6838a95b216691468e2'))
         revocationpubkey = derive_blinded_pubkey(revocation_basepoint, per_commitment_point)
         self.assertEqual(revocationpubkey, bfh('02916e326636d19c33f13e8c0c3a03dd157f332f3e99c317c141dd865eb01f8ff0'))
+
+    def test_per_commitment_secret_from_seed(self):
+        self.assertEqual(bh2u(0x915c75942a26bb3a433a8ce2cb0427c29ec6c1775cfc78328b57f6ba7bfeaa9c.to_bytes(byteorder="big", length=32)),
+                         bh2u(get_per_commitment_secret_from_seed(0x0101010101010101010101010101010101010101010101010101010101010101, 1).to_bytes(byteorder="big", length=32)))
+
+        self.assertEqual(bh2u(0x02a40c85b6f28da08dfdbe0926c53fab2de6d28c10301f8f7c4073d5e42e3148.to_bytes(byteorder="big", length=32)),
+                         bh2u(get_per_commitment_secret_from_seed(0x0000000000000000000000000000000000000000000000000000000000000000, 281474976710655).to_bytes(byteorder="big", length=32)))
+        #self.assertEqual(0x7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc,
+        #                 get_per_commitment_secret_from_seed(0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF, 281474976710655))
+        #self.assertEqual(0x56f4008fb007ca9acf0e15b054d5c9fd12ee06cea347914ddbaed70d1c13a528,
+        #                 get_per_commitment_secret_from_seed(0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF, 0xaaaaaaaaaaa))
+        #self.assertEqual(0x9015daaeb06dba4ccc05b91b2f73bd54405f2be9f217fbacd3c5ac2e62327d31,
+        #                 get_per_commitment_secret_from_seed(0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF, 0x555555555555))
+