def Sanitization(self, pk, vk, ct, Rand):
a = []
C2prime = 1
s = group.random(ZR)
if pair(Rand['Rprime'], Rand['Sprime']) == pair(
Rand['vkprime'],
Rand['ekprime']) * pair(pk['g_2'], vk['Y']) and pair(
Rand['Rprime'],
Rand['Tprime']) == pair(vk['vk'], Rand['Sprime']) * pair(
pk['g_2'], pk['h_i'][0]):
Com_set = list(set(pk['uni']) - set(ct['policy']))
for attrs in Com_set:
a.append(group.hash(attrs, ZR))
(indices, coeff_mult) = Zero_poly(a, len(a) - 1, [0], [1])
Coeffs = list(reversed(coeff_mult))
for i in range(len(indices)):
C2prime *= (pk['h_i'][i + 1]**Coeffs[i])
Cprime = ct['C'] * (pk['e_gg_alpha']**s)
C1prime = ct['C1'] * (pk['g_2']**(-s))
C2prime = ct['C2'] * (C2prime**s)
ctt = {
'Cprime': Cprime,
'C1prime': C1prime,
'C2prime': C2prime,
'policy': ct['policy']
}
return (ctt)
else:
return (None)
def decrypt(self, pk, sk, ctt):
A = list(set(sk['B'])-set(ctt['policy']))
a = []; z = 1
for attrs in A:
a.append(group.hash(attrs, ZR))
(indices,coeff_mult) = Zero_poly(a,len(a)-1,[0],[1])
Coeffs = list(reversed(coeff_mult))
for i in range(len(indices)-1):
z *= pk['h_i'][i] ** Coeffs[i+1]
V = (pair(ctt['C1prime'],z) * pair(sk['dk'],ctt['C2prime']))
return ctt['Cprime'] * (V**(-1/Coeffs[0]))
def EncKGen(self, pk, sgk, vk, P, U):
a=[]; Ek=1
Com_set= list(set(pk['uni']) - set(P))
for attrs in Com_set:
a.append(group.hash(attrs, ZR))
(indices,coeff_mult)=Zero_poly(a,len(a)-1,[0],[1])
Coeffs=list(reversed(coeff_mult))
for i in range(len(indices)):
Ek*= (pk['h_i'][i+1] ** Coeffs[i])
ek = {'ek':Ek}
t = group.random(ZR)
R = pk['g_2']**t
S = (Ek ** (sgk['v']/t)) * (vk['Y']**(1/t))
T = (S ** (sgk['v']/t)) * (pk['h_i'][0]**(1/t))
W = pk['h_i'][0]**(1/t)
sign={'R':R, 'S':S, 'T':T, 'W':W}
return (ek,sign)