def encrypt(bit, key, s_size=31, e_size=16, p=P):
""" usage: encrypt(bit, key,
s_size=31, e_size=16, p=P) => ciphertext
Returns a ciphertext integer. """
a, ai = key
s = (random_integer(s_size) >> 1) << 1
e = random_integer(e_size)
return ((a * (s + bit)) + e) % p
def encrypt(bit, key, s_size=31, e_size=16, p=P):
""" usage: encrypt(bit, key,
s_size=31, e_size=16, p=P) => ciphertext
Returns a ciphertext integer. """
a, ai = key
s = (random_integer(s_size) >> 1) << 1
e = random_integer(e_size)
return ((a * (s + bit)) + e) % p
def generate_secret_key(inverse_size=64, p=P):
""" usage: generate_secret_key(inverse_size=64, p=P) => a, ai
Returns 2 integers.
The size of the inverse places a limit on how many cipher multiplications may be performed. """
ai = random_integer(inverse_size)
return modular_inverse(ai, p), ai
def generate_secret_key(inverse_size=64, p=P):
""" usage: generate_secret_key(inverse_size=64, p=P) => a, ai
Returns 2 integers.
The size of the inverse places a limit on how many cipher multiplications may be performed. """
ai = random_integer(inverse_size)
return modular_inverse(ai, p), ai
def generate_public_key(private_key, parameters=PARAMETERS):
""" usage: generate_public_key(private_key, parameters=PARAMETERS) => public_key : int
Returns a pubic key for use with the key agreement scheme.
It is recommended to use generate_keypair instead. """
s = private_key
r = random_integer(parameters["r_size"])
return ((parameters['e'] * s) + r) % parameters['n']
def generate_public_key(private_key, parameters=PARAMETERS):
""" usage: generate_public_key(private_key, parameters=PARAMETERS) => public_key : int
Returns a pubic key for use with the key agreement scheme.
It is recommended to use generate_keypair instead. """
s = private_key
r = random_integer(parameters["r_size"])
return ((parameters['e'] * s) + r) % parameters['n']
def generate_backdoor_private_key(parameters=PARAMETERS):
""" usage: generate_backdoor_private_key(parameters=PARAMETERS) => backdoor_key : tuple
Generates a private backdoor key.
It is recommended to use generate_backdoor_keypair instead. """
d_size = parameters["d_size"]
n_size = parameters["n_size"]
k = random_integer(parameters["k_size"])
while True:
d = random_integer(d_size) | (1 << (d_size * 8))
n = random_integer(n_size) | (1 << (n_size * 8))
try:
modular_inverse(d, n - k)
except ValueError:
continue
else:
break
return d, n, n - k
def generate_backdoor_private_key(parameters=PARAMETERS):
""" usage: generate_backdoor_private_key(parameters=PARAMETERS) => backdoor_key : tuple
Generates a private backdoor key.
It is recommended to use generate_backdoor_keypair instead. """
d_size = parameters["d_size"]
n_size = parameters["n_size"]
k = random_integer(parameters["k_size"])
while True:
d = random_integer(d_size) | (1 << (d_size * 8))
n = random_integer(n_size) | (1 << (n_size * 8))
try:
modular_inverse(d, n - k)
except ValueError:
continue
else:
break
return d, n, n - k
def test_encrypt_decrypt():
key = generate_secret_key()
iterations = 10000
for count in range(iterations):
bit = random_integer(1) & 1
ciphertext = encrypt(bit, key)
_bit = decrypt(ciphertext, key)
if bit != _bit:
raise Warning("cipher.py unit test failed.")
for count in range(iterations):
for bit1 in range(2):
for bit2 in range(2):
assert bit1 in (0, 1)
assert bit2 in (0, 1)
ciphertext1 = encrypt(bit1, key)
ciphertext2 = encrypt(bit2, key)
ciphertext3 = ciphertext1 + ciphertext2
ciphertext4 = ciphertext1 * ciphertext2
plaintext3 = decrypt(ciphertext3, key)
plaintext4 = decrypt(ciphertext4, key, depth=2)
assert plaintext3 == (bit1 ^ bit2)
assert plaintext4 == (bit1 & bit2), (bit1, bit2)
print("cipher.py unit test passed")
def test_encrypt_decrypt():
key = generate_secret_key()
iterations = 10000
for count in range(iterations):
bit = random_integer(1) & 1
ciphertext = encrypt(bit, key)
_bit = decrypt(ciphertext, key)
if bit != _bit:
raise Warning("cipher.py unit test failed.")
for count in range(iterations):
for bit1 in range(2):
for bit2 in range(2):
assert bit1 in (0, 1)
assert bit2 in (0, 1)
ciphertext1 = encrypt(bit1, key)
ciphertext2 = encrypt(bit2, key)
ciphertext3 = ciphertext1 + ciphertext2
ciphertext4 = ciphertext1 * ciphertext2
plaintext3 = decrypt(ciphertext3, key)
plaintext4 = decrypt(ciphertext4, key, depth=2)
assert plaintext3 == (bit1 ^ bit2)
assert plaintext4 == (bit1 & bit2), (bit1, bit2)
print("cipher.py unit test passed")
def generate_private_key(parameters=PARAMETERS):
""" usage: generate_private_key(parameters=PARAMETERS) => private_key : int
Returns a private key for use with the key agreement scheme.
It is recommended to use generate_keypair instead. """
return random_integer(parameters["s_size"])
def generate_private_key(parameters=PARAMETERS):
""" usage: generate_private_key(parameters=PARAMETERS) => private_key : int
Returns a private key for use with the key agreement scheme.
It is recommended to use generate_keypair instead. """
return random_integer(parameters["s_size"])
