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Make test framework produce lowS signatures

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This commit is contained in:
Johnson Lau 2016-08-24 14:44:17 +08:00
parent 4c0c25a604
commit 9f0397aff7
1 changed files with 23 additions and 2 deletions
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25
qa/rpc-tests/test_framework/key.py
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@ -75,6 +75,9 @@ ssl.EC_POINT_mul.argtypes = [ctypes.c_void_p, ctypes.c_void_p, ctypes.c_void_p,
# this specifies the curve used with ECDSA.
NID_secp256k1 = 714 # from openssl/obj_mac.h
SECP256K1_ORDER = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141
SECP256K1_ORDER_HALF = SECP256K1_ORDER // 2
# Thx to Sam Devlin for the ctypes magic 64-bit fix.
def _check_result(val, func, args):
if val == 0:
@ -147,7 +150,7 @@ class CECKey(object):
r = self.get_raw_ecdh_key(other_pubkey)
return kdf(r)
def sign(self, hash):
def sign(self, hash, low_s = True):
# FIXME: need unit tests for below cases
if not isinstance(hash, bytes):
raise TypeError('Hash must be bytes instance; got %r' % hash.__class__)
@ -159,7 +162,25 @@ class CECKey(object):
mb_sig = ctypes.create_string_buffer(sig_size0.value)
result = ssl.ECDSA_sign(0, hash, len(hash), mb_sig, ctypes.byref(sig_size0), self.k)
assert 1 == result
return mb_sig.raw[:sig_size0.value]
assert mb_sig.raw[0] == 0x30
assert mb_sig.raw[1] == sig_size0.value - 2
total_size = mb_sig.raw[1]
assert mb_sig.raw[2] == 2
r_size = mb_sig.raw[3]
assert mb_sig.raw[4 + r_size] == 2
s_size = mb_sig.raw[5 + r_size]
s_value = int.from_bytes(mb_sig.raw[6+r_size:6+r_size+s_size], byteorder='big')
if (not low_s) or s_value <= SECP256K1_ORDER_HALF:
return mb_sig.raw[:sig_size0.value]
else:
low_s_value = SECP256K1_ORDER - s_value
low_s_bytes = (low_s_value).to_bytes(33, byteorder='big')
while len(low_s_bytes) > 1 and low_s_bytes[0] == 0 and low_s_bytes[1] < 0x80:
low_s_bytes = low_s_bytes[1:]
new_s_size = len(low_s_bytes)
new_total_size_byte = (total_size + new_s_size - s_size).to_bytes(1,byteorder='big')
new_s_size_byte = (new_s_size).to_bytes(1,byteorder='big')
return b'\x30' + new_total_size_byte + mb_sig.raw[2:5+r_size] + new_s_size_byte + low_s_bytes
def verify(self, hash, sig):
"""Verify a DER signature"""