def from_sec(string,
curve=curves.SECP256k1,
hashfunc=sha1,
validate_point=True):
"""Convert a public key in SEC binary format to a verifying key."""
# based on code from https://github.com/richardkiss/pycoin
if string.startswith(b('\x04')):
# uncompressed
return VerifyingKey.from_string(string[1:], curve, hashfunc,
validate_point)
elif string.startswith(b('\x02')) or string.startswith(b('\x03')):
# compressed
is_even = string.startswith(b('\x02'))
x = string_to_number(string[1:])
order = curve.order
p = curve.curve.p()
alpha = (pow(x, 3, p) + (curve.curve.a() * x) + curve.curve.b()) % p
beta = square_root_mod_prime(alpha, p)
if is_even == bool(beta & 1):
y = p - beta
else:
y = beta
if validate_point:
assert ecdsa.point_is_valid(curve.generator, x, y)
point = ellipticcurve.Point(curve.curve, x, y, order)
return VerifyingKey.from_public_point(point, curve, hashfunc)
def get_ecdsa_verifying_key(pub):
#some shenanigans required to validate a transaction sig; see
#python.ecdsa PR #54. This will be a lot simpler when that's merged.
#https://github.com/warner/python-ecdsa/pull/54/files
if not pub[0] in ["\x02", "\x03"]:
log.debug("Invalid pubkey")
return None
is_even = pub.startswith('\x02')
x = string_to_number(pub[1:])
order = SECP256k1.order
p = SECP256k1.curve.p()
alpha = (pow(x, 3, p) +
(SECP256k1.curve.a() * x) + SECP256k1.curve.b()) % p
beta = square_root_mod_prime(alpha, p)
if is_even == bool(beta & 1):
y = p - beta
else:
y = beta
if not point_is_valid(SECP256k1.generator, x, y):
return None
point = Point(SECP256k1.curve, x, y, order)
return VerifyingKey.from_public_point(point,
SECP256k1,
hashfunc=hashlib.sha256)
def verify_point(G, p):
"""
Verifies a point on the elliptic curve G.curve
:param G: elliptic curve base point, a generator of the elliptic curve with large prime order n
:param p: point
:return: boolean
"""
return point_is_valid(G, p.x(), p.y())
def from_sec(string, curve=curves.SECP256k1, hashfunc=sha1, validate_point=True):
"""Convert a public key in SEC binary format to a verifying key."""
# based on code from https://github.com/richardkiss/pycoin
if string.startswith(b("\x04")):
# uncompressed
return VerifyingKey.from_string(string[1:], curve, hashfunc, validate_point)
elif string.startswith(b("\x02")) or string.startswith(b("\x03")):
# compressed
is_even = string.startswith(b("\x02"))
x = string_to_number(string[1:])
order = curve.order
p = curve.curve.p()
alpha = (pow(x, 3, p) + (curve.curve.a() * x) + curve.curve.b()) % p
beta = square_root_mod_prime(alpha, p)
if is_even == bool(beta & 1):
y = p - beta
else:
y = beta
if validate_point:
assert ecdsa.point_is_valid(curve.generator, x, y)
point = ellipticcurve.Point(curve.curve, x, y, order)
return VerifyingKey.from_public_point(point, curve, hashfunc)
def uncompress(string: bytes, curve=SECP256k1) -> Point:
if string[:1] not in (b'\x02', b'\x03'):
raise MalformedPoint("Malformed compressed point encoding")
is_even = string[:1] == b'\x02'
x = string_to_number(string[1:])
order = curve.order
p = curve.curve.p()
alpha = (pow(x, 3, p) + (curve.curve.a() * x) + curve.curve.b()) % p
try:
beta = square_root_mod_prime(alpha, p)
except SquareRootError as e:
raise MalformedPoint(
"Encoding does not correspond to a point on curve", e
)
if is_even == bool(beta & 1):
y = p - beta
else:
y = beta
if not ecdsa.point_is_valid(curve.generator, x, y):
raise MalformedPoint("Point does not lie on curve")
return point_to_pubkey_bytes(Point(curve.curve, x, y, order))
def get_ecdsa_verifying_key(pub):
#some shenanigans required to validate a transaction sig; see
#python.ecdsa PR #54. This will be a lot simpler when that's merged.
#https://github.com/warner/python-ecdsa/pull/54/files
if not pub[0] in ["\x02", "\x03"]:
log.debug("Invalid pubkey")
return None
is_even = pub.startswith('\x02')
x = string_to_number(pub[1:])
order = SECP256k1.order
p = SECP256k1.curve.p()
alpha = (pow(x, 3, p) + (SECP256k1.curve.a() * x) + SECP256k1.curve.b()) % p
beta = square_root_mod_prime(alpha, p)
if is_even == bool(beta & 1):
y = p - beta
else:
y = beta
if not point_is_valid(SECP256k1.generator, x, y):
return None
point = Point(SECP256k1.curve, x, y, order)
return VerifyingKey.from_public_point(point, SECP256k1,
hashfunc=hashlib.sha256)