def getNUMS(index=0):
"""Taking secp256k1's G as a seed,
either in compressed or uncompressed form,
append "index" as a byte, and append a second byte "counter"
try to create a new NUMS base point from the sha256 of that
bytestring. Loop counter and alternate compressed/uncompressed
until finding a valid curve point. The first such point is
considered as "the" NUMS base point alternative for this index value.
The search process is of course deterministic/repeatable, so
it's fine to just store a list of all the correct values for
each index, but for transparency left in code for initialization
by any user.
The NUMS generator generated is returned as a secp256k1.PublicKey.
"""
assert index in range(256)
nums_point = None
for G in [getG(True), getG(False)]:
seed = G + struct.pack(b'B', index)
for counter in range(256):
seed_c = seed + struct.pack(b'B', counter)
hashed_seed = hashlib.sha256(seed_c).digest()
#Every x-coord on the curve has two y-values, encoded
#in compressed form with 02/03 parity byte. We just
#choose the former.
claimed_point = b"\x02" + hashed_seed
try:
nums_point = podle_PublicKey(claimed_point)
return nums_point
except:
continue
assert False, "It seems inconceivable, doesn't it?" # pragma: no cover
def __init__(self,
u=None,
priv=None,
P=None,
P2=None,
s=None,
e=None,
used=False):
#This class allows storing of utxo in format "txid:n" only for
#convenience of storage/access; it doesn't check or use the data.
#Arguments must be provided in hex.
self.u = u
if not priv:
if P:
#Construct a pubkey from raw hex
self.P = podle_PublicKey(binascii.unhexlify(P))
else:
self.P = None
else:
if P:
raise PoDLEError("Pubkey should not be provided with privkey")
#any other formatting abnormality will just throw in PrivateKey
if len(priv) == 66 and priv[-2:] == '01':
priv = priv[:-2]
self.priv = podle_PrivateKey(binascii.unhexlify(priv))
self.P = self.priv.public_key
if P2:
self.P2 = podle_PublicKey(binascii.unhexlify(P2))
else:
self.P2 = None
#These sig values should be passed in hex.
self.s = None
self.e = None
if s:
self.s = binascii.unhexlify(s)
if e:
self.e = binascii.unhexlify(e)
#Optionally maintain usage state (boolean)
self.used = used
#the H(P2) value
self.commitment = None
def __init__(self,
u=None,
priv=None,
P=None,
P2=None,
s=None,
e=None,
used=False):
#This class allows storing of utxo in format "txid:n" only for
#convenience of storage/access; it doesn't check or use the data.
#Arguments must be provided in binary not hex.
self.u = u
if not priv:
if P:
self.P = podle_PublicKey(P)
else:
self.P = None
else:
if P:
raise PoDLEError("Pubkey should not be provided with privkey")
#any other formatting abnormality will just throw in PrivateKey
if len(priv) == 33 and priv[-1:] == b"\x01":
priv = priv[:-1]
self.priv = podle_PrivateKey(priv)
self.P = self.priv.pub
if P2:
self.P2 = podle_PublicKey(P2)
else:
self.P2 = None
self.s = None
self.e = None
if s:
self.s = s
if e:
self.e = e
#Optionally maintain usage state (boolean)
self.used = used
#the H(P2) value
self.commitment = None