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keystore/transactions: fix overflow of derivation path indices

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fixes #5366
This commit is contained in:
SomberNight
2019-05-20 23:53:57 +02:00
parent a8b939711a
commit 6ad24ea3b3
2 changed files with 18 additions and 4 deletions
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17
electrum/keystore.py
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@@ -282,7 +282,13 @@ class Xpub:
return node.eckey.get_public_key_hex(compressed=True)
def get_xpubkey(self, c, i):
s = ''.join(map(lambda x: bitcoin.int_to_hex(x,2), (c, i)))
def encode_path_int(path_int) -> str:
if path_int < 0xffff:
hex = bitcoin.int_to_hex(path_int, 2)
else:
hex = 'ffff' + bitcoin.int_to_hex(path_int, 4)
return hex
s = ''.join(map(encode_path_int, (c, i)))
return 'ff' + bh2u(bitcoin.DecodeBase58Check(self.xpub)) + s
@classmethod
@@ -296,11 +302,14 @@ class Xpub:
# derivation:
dd = pk[78:]
s = []
# FIXME: due to an oversight, levels in the derivation are only
# allocated 2 bytes, instead of 4 (in bip32)
while dd:
n = int(bitcoin.rev_hex(bh2u(dd[0:2])), 16)
# 2 bytes for derivation path index
n = int.from_bytes(dd[0:2], byteorder="little")
dd = dd[2:]
# in case of overflow, drop these 2 bytes; and use next 4 bytes instead
if n == 0xffff:
n = int.from_bytes(dd[0:4], byteorder="little")
dd = dd[4:]
s.append(n)
assert len(s) == 2
return xkey, s