def build_linear_approximation_table(sbox, exhaustive=False):
approximations = {}
sbox_size = len(sbox)
if exhaustive:
for byte in range(sbox_size):
for mask1 in range(1, sbox_size):
for mask2 in range(1, sbox_size):
input = byte
input_parity = hamming_weight(input & mask1) % 2
output_parity = hamming_weight(sbox[input] & mask2) % 2
if input_parity == output_parity:
try:
approximations[(mask1, mask2)] += 1
except KeyError:
approximations[(mask1, mask2)] = 1
else:
for byte in range(sbox_size):
for mask1 in range(1, sbox_size):
mask2 = mask1
input = byte
input_parity = hamming_weight(input & mask1) % 2
output_parity = hamming_weight(sbox[input] & mask2) % 2
if input_parity == output_parity:
try:
approximations[(mask1, mask2)] += 1
except KeyError:
approximations[(mask1, mask2)] = 1
return approximations
def test_bit_transposition():
data = range(16)
_sum = sum(hamming_weight(byte) for byte in data)
_data = data[:]
#print_state_4x4(data, "Before: ")
bit_transposition_involution(data, 0)
#print_state_4x4(data, "After: ")
rotated = data[:]
bit_transposition_involution(data, 0)
assert data == _data
bit_transposition_involution(data, 8)
#print_state_4x4(data, "Bottom transposed: ")
bit_transposition_involution(data, 8)
assert data == _data
print_state_4x4(data, "Before: ")
bit_transposition_hackers_delight(data, 0)
_sum_after = sum(hamming_weight(byte) for byte in data)
assert _sum == _sum_after, (_sum, _sum_after)
print_state_4x4(data, "After: ")
#assert data == rotated, (data, rotated)
bit_transposition_hackers_delight(data, 0)
print_state_4x4(data, "Reverted: ")
_sum_after = sum(hamming_weight(byte) for byte in data)
assert _sum == _sum_after, (_sum, _sum_after)
#assert data == _data
data = _data[:]
print_state_4x4(data, "Bottom before: ")
bit_transposition_hackers_delight(data, 8)
print_state_4x4(data, "Bottom after: ")
_sum_after = sum(hamming_weight(byte) for byte in data)
assert _sum == _sum_after, (_sum, _sum_after)
def calculate_branch_number(substitution_diffusion_substitution_layer, datasize):
raise NotImplementedError()
min_branch_number = 0xFFFFFFFF
for difference in range(1, 256):
data = bytearray(datasize)
data2 = bytearray(datasize)
data2[0] = data[0] ^ difference
substitution_diffusion_substitution_layer(data)
substitution_diffusion_substitution_layer(data2)
output_difference = data2[0] ^ data[0]
min_branch_number = min(hamming_weight(difference) + hamming_weight(output_difference), min_branch_number)
return min_branch_number
def calculate_branch_number(substitution_diffusion_substitution_layer,
datasize):
raise NotImplementedError()
min_branch_number = 0xFFFFFFFF
for difference in range(1, 256):
data = bytearray(datasize)
data2 = bytearray(datasize)
data2[0] = data[0] ^ difference
substitution_diffusion_substitution_layer(data)
substitution_diffusion_substitution_layer(data2)
output_difference = data2[0] ^ data[0]
min_branch_number = min(
hamming_weight(difference) + hamming_weight(output_difference),
min_branch_number)
return min_branch_number
def nonlinear_function3(data, mask=1 << 7):
# data ^= 1 << (data % 8)
for bit_number in range(8):
other_bits = (data ^ (data & (1 << bit_number))) % 2
weight = hamming_weight(other_bits)
data ^= other_bits << bit_number
data = (data + (other_bits + weight)) % 256
data ^= 1 << (data % 8)
return data
def generate_public_key(private_key, security_level=SECURITY_LEVEL):
public_key = []
modulus = 2 ** (security_level * 8)
for public_key_element_number in range(security_level):
element = []
shares = secret_split(1, security_level, hamming_weight(private_key), modulus)
for counter in range(security_level * 8):
if (private_key >> counter) & 1:
element.append(shares.pop(0))
else:
element.append(random_integer(security_level))
public_key.append(element)
return public_key
def generate_public_key(private_key, security_level=SECURITY_LEVEL, dimensions=DIMENSIONS):
public_key = []
modulus = 2 ** (security_level * 8)
for public_key_element_number in range(dimensions):
element = []
shares = secret_split(0, security_level, hamming_weight(private_key), modulus)
for counter in range(security_level * 8):
if (private_key >> counter) & 1:
element.append(shares.pop(0))
else:
element.append(random_integer(security_level))
public_key.append(element)
return public_key
def test_bit_transposition():
data = range(16)
_sum = sum(hamming_weight(byte) for byte in data)
_data = data[:]
#print_state_4x4(data, "Before: ")
bit_transposition_involution(data, 0)
#print_state_4x4(data, "After: ")
rotated = data[:]
bit_transposition_involution(data, 0)
assert data == _data
bit_transposition_involution(data, 8)
#print_state_4x4(data, "Bottom transposed: ")
bit_transposition_involution(data, 8)
assert data == _data
print_state_4x4(data, "Before: ")
bit_transposition_hackers_delight(data, 0)
_sum_after = sum(hamming_weight(byte) for byte in data)
assert _sum == _sum_after, (_sum, _sum_after)
print_state_4x4(data, "After: ")
#assert data == rotated, (data, rotated)
bit_transposition_hackers_delight(data, 0)
print_state_4x4(data, "Reverted: ")
_sum_after = sum(hamming_weight(byte) for byte in data)
assert _sum == _sum_after, (_sum, _sum_after)
#assert data == _data
data = _data[:]
print_state_4x4(data, "Bottom before: ")
bit_transposition_hackers_delight(data, 8)
print_state_4x4(data, "Bottom after: ")
_sum_after = sum(hamming_weight(byte) for byte in data)
assert _sum == _sum_after, (_sum, _sum_after)