def check_ring_singature(prefix_hash, image, pubs, sig):
"""
Checks ring signature generated with generate_ring_signature
"""
image_unp = crypto.ge_frombytes_vartime(image)
image_pre = crypto.ge_dsm_precomp(image_unp)
buff_off = len(prefix_hash)
buff = bytearray(buff_off + 2 * 32 * len(pubs))
memcpy(buff, 0, prefix_hash, 0, buff_off)
mvbuff = memoryview(buff)
sum = crypto.sc_0()
for i in range(len(pubs)):
if crypto.sc_check(sig[i][0]) != 0 or crypto.sc_check(sig[i][1]) != 0:
return False
tmp3 = crypto.ge_frombytes_vartime(pubs[i])
tmp2 = crypto.ge_double_scalarmult_base_vartime(
sig[i][0], tmp3, sig[i][1])
crypto.encodepoint_into(mvbuff[buff_off:buff_off + 32], tmp2)
buff_off += 32
tmp3 = crypto.hash_to_point(crypto.encodepoint(pubs[i]))
tmp2 = crypto.ge_double_scalarmult_precomp_vartime(
sig[i][1], tmp3, sig[i][0], image_pre)
crypto.encodepoint_into(mvbuff[buff_off:buff_off + 32], tmp2)
buff_off += 32
sum = crypto.sc_add(sum, sig[i][0])
h = crypto.hash_to_scalar(buff)
h = crypto.sc_sub(h, sum)
return crypto.sc_isnonzero(h) == 0
def next(self, num, buff=None):
buff = buff if buff is not None else bytearray(num)
off = 0
while (num - off) > 0:
left = num - off
cur = self._gen()
tocopy = min(len(cur), left)
memcpy(buff, off, cur, 0, tocopy)
off += tocopy
return buff
def generate_ring_signature(prefix_hash,
image,
pubs,
sec,
sec_idx,
test=False):
"""
Generates ring signature with key image.
void crypto_ops::generate_ring_signature()
"""
if test:
t = crypto.scalarmult_base(sec)
if not crypto.point_eq(t, pubs[sec_idx]):
raise ValueError("Invalid sec key")
k_i = monero.generate_key_image(crypto.encodepoint(pubs[sec_idx]), sec)
if not crypto.point_eq(k_i, image):
raise ValueError("Key image invalid")
for k in pubs:
crypto.ge_frombytes_vartime_check(k)
image_unp = crypto.ge_frombytes_vartime(image)
image_pre = crypto.ge_dsm_precomp(image_unp)
buff_off = len(prefix_hash)
buff = bytearray(buff_off + 2 * 32 * len(pubs))
memcpy(buff, 0, prefix_hash, 0, buff_off)
mvbuff = memoryview(buff)
sum = crypto.sc_0()
k = crypto.sc_0()
sig = []
for i in range(len(pubs)):
sig.append([crypto.sc_0(), crypto.sc_0()]) # c, r
for i in range(len(pubs)):
if i == sec_idx:
k = crypto.random_scalar()
tmp3 = crypto.scalarmult_base(k)
crypto.encodepoint_into(mvbuff[buff_off:buff_off + 32], tmp3)
buff_off += 32
tmp3 = crypto.hash_to_point(crypto.encodepoint(pubs[i]))
tmp2 = crypto.scalarmult(tmp3, k)
crypto.encodepoint_into(mvbuff[buff_off:buff_off + 32], tmp2)
buff_off += 32
else:
sig[i] = [crypto.random_scalar(), crypto.random_scalar()]
tmp3 = crypto.ge_frombytes_vartime(pubs[i])
tmp2 = crypto.ge_double_scalarmult_base_vartime(
sig[i][0], tmp3, sig[i][1])
crypto.encodepoint_into(mvbuff[buff_off:buff_off + 32], tmp2)
buff_off += 32
tmp3 = crypto.hash_to_point(crypto.encodepoint(tmp3))
tmp2 = crypto.ge_double_scalarmult_precomp_vartime(
sig[i][1], tmp3, sig[i][0], image_pre)
crypto.encodepoint_into(mvbuff[buff_off:buff_off + 32], tmp2)
buff_off += 32
sum = crypto.sc_add(sum, sig[i][0])
h = crypto.hash_to_scalar(buff)
sig[sec_idx][0] = crypto.sc_sub(h, sum)
sig[sec_idx][1] = crypto.sc_mulsub(sig[sec_idx][0], sec, k)
return sig
def dump_rsig_bp(rsig):
from monero_glue.compat.utils import memcpy
if len(rsig.L) > 127:
raise ValueError("Too large")
# Manual serialization as the generic purpose misc.dump_msg_gc
# is more memory intensive which is not desired in the range proof section.
# BP: V, A, S, T1, T2, taux, mu, L, R, a, b, t
# Commitment vector V is not serialized
# Vector size under 127 thus varint occupies 1 B
buff_size = 32 * (9 + 2 * (len(rsig.L))) + 2
buff = bytearray(buff_size)
memcpy(buff, 0, rsig.A, 0, 32)
memcpy(buff, 32, rsig.S, 0, 32)
memcpy(buff, 32 * 2, rsig.T1, 0, 32)
memcpy(buff, 32 * 3, rsig.T2, 0, 32)
memcpy(buff, 32 * 4, rsig.taux, 0, 32)
memcpy(buff, 32 * 5, rsig.mu, 0, 32)
buff[32 * 6] = len(rsig.L)
offset = 32 * 6 + 1
for x in rsig.L:
memcpy(buff, offset, x, 0, 32)
offset += 32
buff[offset] = len(rsig.R)
offset += 1
for x in rsig.R:
memcpy(buff, offset, x, 0, 32)
offset += 32
memcpy(buff, offset, rsig.a, 0, 32)
offset += 32
memcpy(buff, offset, rsig.b, 0, 32)
offset += 32
memcpy(buff, offset, rsig.t, 0, 32)
return buff