def gen_mlsag_rows(message, rv, pk, xx, kLRki, index, dsRows, rows, cols):
"""
MLSAG computation - the part with secret keys
:param message:
:param rv:
:param pk:
:param xx:
:param kLRki:
:param index:
:param dsRows:
:param rows:
:param cols:
:return:
"""
Ip = key_vector(dsRows)
rv.II = key_vector(dsRows)
alpha = key_vector(rows)
rv.ss = key_matrix(rows, cols)
hasher = hasher_message(message)
for i in range(dsRows):
hasher.update(crypto.encodepoint(pk[index][i]))
if kLRki:
alpha[i] = kLRki.k
rv.II[i] = kLRki.ki
hasher.update(crypto.encodepoint(kLRki.L))
hasher.update(crypto.encodepoint(kLRki.R))
else:
Hi = crypto.hash_to_point(crypto.encodepoint(
pk[index][i])) # originally hashToPoint()
alpha[i] = crypto.random_scalar()
aGi = crypto.scalarmult_base(alpha[i])
aHPi = crypto.scalarmult(Hi, alpha[i])
rv.II[i] = crypto.scalarmult(Hi, xx[i])
hasher.update(crypto.encodepoint(aGi))
hasher.update(crypto.encodepoint(aHPi))
Ip[i] = crypto.precomp(rv.II[i])
for i in range(dsRows, rows):
alpha[i] = crypto.random_scalar()
aGi = crypto.scalarmult_base(alpha[i])
hasher.update(crypto.encodepoint(pk[index][i]))
hasher.update(crypto.encodepoint(aGi))
c_old = hasher.digest()
c_old = crypto.decodeint(c_old)
return c_old, Ip, alpha
def ver_mlsag_ext(message, pk, rv, dsRows):
"""
Multilayered Spontaneous Anonymous Group Signatures (MLSAG signatures)
c.f. http://eprint.iacr.org/2015/1098 section 2.
keyImageV just does I[i] = xx[i] * Hash(xx[i] * G) for each i
:param message:
:param pk: matrix of EC points, point form.
:param rv:
:param dsRows:
:return:
"""
rows, cols = ver_mlsag_assert(pk, rv, dsRows)
c_old = rv.cc
Ip = key_vector(dsRows)
for i in range(dsRows):
Ip[i] = crypto.precomp(rv.II[i])
i = 0
while i < cols:
c = 0
hasher = hasher_message(message)
for j in range(dsRows):
L = crypto.add_keys2(rv.ss[i][j], c_old, pk[i][j])
Hi = crypto.hash_to_point(crypto.encodepoint(
pk[i][j])) # originally hashToPoint()
R = crypto.add_keys3(rv.ss[i][j], Hi, c_old, Ip[j])
hasher.update(crypto.encodepoint(pk[i][j]))
hasher.update(crypto.encodepoint(L))
hasher.update(crypto.encodepoint(R))
for j in range(dsRows, rows):
L = crypto.add_keys2(rv.ss[i][j], c_old, pk[i][j])
hasher.update(crypto.encodepoint(pk[i][j]))
hasher.update(crypto.encodepoint(L))
c = crypto.decodeint(hasher.digest())
c_old = c
i += 1
c = crypto.sc_sub(c_old, rv.cc)
return not crypto.sc_isnonzero(c)