def extract_at(pwd, features, index):
index += 1
pwd = mpz(crypt.get_bit_str_from_byte(pwd), base=2)
if features[index - 1] >= config.ti: # pick the other column of the table
x = crypt.p(mpz(index << 1), config.r)
y = gmpy2.sub(table[index - 1][0], crypt.g(mpz(index << 1), config.r ^ pwd))
return x, y
else:
x = crypt.p(mpz((index << 1) + 1), config.r)
y = gmpy2.sub(table[index - 1][1], crypt.g(mpz((index << 1) + 1), config.r ^ pwd))
return x, y
def extract(pwd, features):
coordinates = []
i = 0
pwd = mpz(crypt.get_bit_str_from_byte(pwd), base=2)
for feature in features:
i += 1
if feature < config.ti:
x = crypt.p(mpz(i << 1), config.r)
y = gmpy2.sub(table[i - 1][0], crypt.g(mpz(i << 1), config.r ^ pwd))
coordinates.append((x, y))
else:
x = crypt.p(mpz((i << 1) + 1), config.r)
y = gmpy2.sub(table[i - 1][1], crypt.g(mpz((i << 1) + 1), config.r ^ pwd))
coordinates.append((x, y))
while len(coordinates) < config.max_features: # append more coordinates for interpolation
i += 1
x = crypt.p(mpz(i << 1), config.r)
y = gmpy2.sub(table[i - 1][0], crypt.g(mpz(i << 1), config.r ^ pwd))
coordinates.append((x, y))
return coordinates
def generate(pwd, stat):
config.generate_r()
pwd = mpz(crypt.get_bit_str_from_byte(pwd), base=2)
global table
table = [] # clear the table
for i in xrange(config.max_features):
x_0 = crypt.p(mpz((i + 1) << 1), config.r) # calculate x0, x1 and y0, y1
x_1 = crypt.p(mpz(((i + 1) << 1) + 1), config.r)
y_0 = gmpy2.add(poly.calculate(x_0), crypt.g(mpz((i + 1) << 1), config.r ^ pwd)) # use r xor pwd as the key
y_1 = gmpy2.add(poly.calculate(x_1), crypt.g(mpz(((i + 1) << 1) + 1), config.r ^ pwd))
if reader.if_init():
table.append((y_0, y_1)) # if in initialization phase, add correct value
else:
if stat[i][0] is None:
table.append((y_0, y_1)) # if no statistic information is derived
elif (stat[i][1] + stat[i][0] * config.k) < config.ti: # if fast
rand_value = gmpy2.t_mod(config.generate_rand(), config.q)
table.append((y_0, rand_value))
elif (stat[i][1] - stat[i][0] * config.k) > config.ti: # if slow
rand_value = gmpy2.t_mod(config.generate_rand(), config.q)
table.append((rand_value, y_1))
else:
table.append((y_0, y_1))