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electrum-bitcoinprivate
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enforece low S value in signatures (per BIP62)

This commit is contained in:
ThomasV 2015-10-05 09:15:22 +02:00
parent 0fe410d7e6
commit d68042e76e
1 changed files with 14 additions and 1 deletions
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15
lib/bitcoin.py
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@ -468,6 +468,19 @@ class MyVerifyingKey(ecdsa.VerifyingKey):
return klass.from_public_point( Q, curve )
class MySigningKey(ecdsa.SigningKey):
"""Enforce low S values in signatures"""
def sign_number(self, number, entropy=None, k=None):
curve = SECP256k1
G = curve.generator
order = G.order()
r, s = ecdsa.SigningKey.sign_number(self, number, entropy, k)
if s > order/2:
s = order - s
return r, s
class EC_KEY(object):
def __init__( self, k ):
@ -480,7 +493,7 @@ class EC_KEY(object):
return point_to_ser(self.pubkey.point, compressed).encode('hex')
def sign(self, msg_hash):
private_key = ecdsa.SigningKey.from_secret_exponent(self.secret, curve = SECP256k1)
private_key = MySigningKey.from_secret_exponent(self.secret, curve = SECP256k1)
public_key = private_key.get_verifying_key()
signature = private_key.sign_digest_deterministic(msg_hash, hashfunc=hashlib.sha256, sigencode = ecdsa.util.sigencode_string)
assert public_key.verify_digest(signature, msg_hash, sigdecode = ecdsa.util.sigdecode_string)