def sharedb(received):
global b_key
(pka, seed) = received
a_coeffs = gen_a(seed)
s_coeffs = get_noise()
e_coeffs = get_noise()
b_coeffs = poly.pointwise(a_coeffs, s_coeffs)
b_coeffs = poly.add(b_coeffs, e_coeffs)
v_coeffs = poly.pointwise(pka, s_coeffs)
v_coeffs = poly.invntt(v_coeffs)
e_prime = poly.get_noise()
v_coeffs = poly.add(v_coeffs, e_prime)
c_coeffs = poly.helprec(v_coeffs)
b_key = poly.rec(v_coeffs, c_coeffs)
return (c_coeffs, b_coeffs)
def shareda(received):
global a_key, s_hat
(c_coeffs, b_coeffs) = received
v_coeffs = poly.pointwise(s_hat, b_coeffs)
v_coeffs = poly.invntt(v_coeffs)
a_key = poly.rec(v_coeffs, c_coeffs)
return
def keygen(verbose = False):
global s_hat
seed = os.urandom(params.NEWHOPE_SEEDBYTES)
a_coeffs = gen_a(seed)
s_coeffs = get_noise()
s_hat = s_coeffs
e_coeffs = get_noise()
r_coeffs = poly.pointwise(s_coeffs, a_coeffs)
p_coeffs = poly.add(e_coeffs, r_coeffs)
return (p_coeffs, seed)
def send_u(received):
global b_key
#getting s', e' and e'' with phi 16
sprime_coeffs = get_noise()
eprime_coeffs = get_noise()
escndprime_coeffs = get_noise()
#parse the seed to obtain a
(pkb, seed) = received
a_coeffs = parse(seed)
#computing u<-as'+e'
b_coeffs = poly.pointwise(a_coeffs, sprime_coeffs)
u_coeffs = poly.add(b_coeffs, eprime_coeffs)
#computing v<-bs'+e''
v_coeffs = poly.pointwise(pkb, sprime_coeffs)
v_coeffs = poly.add(v_coeffs, escndprime_coeffs)
b_key = v_coeffs
return u_coeffs
def send_b_seed(verbose=False):
global s_hat
#generating the seed with 256 bits
seed = os.urandom(params.NEWHOPE_SEEDBYTES)
#parse the seed to obtain a
a_coeffs = parse(seed)
#getting s and e with phi 16
s_coeffs = get_noise()
s_hat = s_coeffs
e_coeffs = get_noise()
#computing b<- a.s + e
r_coeffs = poly.pointwise(s_coeffs, a_coeffs)
b_coeffs = poly.add(e_coeffs, r_coeffs)
#b and seed are sent to Bob
return (b_coeffs, seed)
def compute_vprime(received):
global a_key, s_hat
u_coeffs = received
vprime_coeffs = poly.pointwise(s_hat, u_coeffs)
a_key = vprime_coeffs
return