def generate_session_key(idA, idB, Ra, Rb, D, x, master_public, entity, l):
P1, P2, Ppub, g = master_public
if entity == 'A':
R = Rb
elif entity == 'B':
R = Ra
else:
raise Exception('Invalid entity')
g1 = ate.pairing(R, D)
g2 = g**x
g3 = g1**x
if (entity == 'B'):
(g1, g2) = (g2, g1)
uidA = sm3_hash(str2hexbytes(idA))
uidB = sm3_hash(str2hexbytes(idB))
kdf_input = uidA + uidB
kdf_input += ec2sp(Ra) + ec2sp(Rb)
kdf_input += fe2sp(g1) + fe2sp(g2) + fe2sp(g3)
sk = sm3_kdf(kdf_input.encode('utf-8'), l)
return sk
def kem_decap(master_public, identity, D, C1, l):
if ec.is_on_curve(C1, ec.b2) == False:
return FAILURE
t = ate.pairing(C1, D)
uid = sm3_hash(str2hexbytes(identity))
kdf_input = ec2sp(C1) + fe2sp(t) + uid
k = sm3_kdf(kdf_input.encode('utf-8'), l)
return k
def kem_encap(master_public, identity, l):
P1, P2, Ppub, g = master_public
Q = public_key_extract('encrypt', master_public, identity)
rand_gen = SystemRandom()
x = rand_gen.randrange(ec.curve_order)
C1 = ec.multiply(Q, x)
t = g**x
uid = sm3_hash(str2hexbytes(identity))
kdf_input = ec2sp(C1) + fe2sp(t) + uid
k = sm3_kdf(kdf_input.encode('utf-8'), l)
return (k, C1)
def encrypt(self, data, pubkey):
msg = data.hex()
k = random_hex(self.para_len)
C1 = self._kg(int(k, 16), self.ecc_table['g'])
xy = self._kg(int(k, 16), pubkey)
x2 = xy[0:self.para_len]
y2 = xy[self.para_len:2 * self.para_len]
ml = len(msg)
t = sm3.sm3_kdf(xy.encode('utf8'), ml / 2)
if int(t, 16) == 0:
return None
else:
form = '%%0%dx' % ml
C2 = form % (int(msg, 16) ^ int(t, 16))
C3 = sm3.sm3_hash(
[i for i in bytes.fromhex('%s%s%s' % (x2, msg, y2))])
return bytes.fromhex('%s%s%s' % (C1, C3, C2))
def decrypt(self, data, privKey):
data = data.hex()
len_2 = 2 * self.para_len
len_3 = len_2 + 64
C1 = data[0:len_2]
C3 = data[len_2:len_3]
C2 = data[len_3:]
xy = self._kg(privKey, C1)
x2 = xy[0:self.para_len]
y2 = xy[self.para_len:len_2]
cl = len(C2)
t = sm3.sm3_kdf(xy.encode('utf8'), cl / 2)
if int(t, 16) == 0:
return None
else:
form = '%%0%dx' % cl
M = form % (int(C2, 16) ^ int(t, 16))
u = sm3.sm3_hash(
[i for i in bytes.fromhex('%s%s%s' % (x2, M, y2))])
return bytes.fromhex(M)
def h2rf(i, z, n):
l = 8 * ceil((5 * bitlen(n)) / 32)
msg = i2sp(i, 1).encode('utf-8')
ha = sm3_kdf(msg + z, l)
h = int(ha, 16)
return (h % (n - 1)) + 1