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minimalist_lwe.py
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minimalist_lwe.py
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from random import randint
from collections.abc import Iterable
from typing import List, Tuple, Any
from math import floor
class MinimalistLWE:
def __init__(self, q: int, n: int):
# stuff to generate public key
self._prime_q = q
self._integer_n = n
# keys
self._privateKey: int = self.gen_privateKey()
self._publicKey: Tuple[List[int], List[int]] = self.gen_publicKey()
#
def gen_privateKey(self) -> int:
return randint(1, 99999)
#
def gen_publicKey(self) -> Tuple[List[int], List[int]]:
A: List[int] = []
E: List[int] = []
B: List[int] = []
# defining A
for n in range(0, self._integer_n):
A.append(randint(1, self._prime_q))
#
# definig errors
for n in range(0, self._integer_n):
E.append(randint(1, 4))
#
# and then, defining B
for n in range(0, self._integer_n):
B.append((A[n] * self._privateKey + E[n]) % self._prime_q)
#
return (A, B)
#
def _perform_u_v(self, bit: int):
u: int = 0
v: int = 0
sumASamples: int = 0
sumBSamples: int = 0
number_of_samples = randint(2, 6)
prev_index = 0
for selectedSample in range(0, number_of_samples):
index = randint(0, self._integer_n - 1)
while prev_index == index:
index = randint(0, self._integer_n - 1)
#
sumASamples += self._publicKey[0][index]
sumBSamples += self._publicKey[1][index]
prev_index = index
#
u = sumASamples % self._prime_q
v = sumBSamples + (self._prime_q / 2) * bit
v = v % self._prime_q
return (u, v)
#
def min_encrypt(self, message: Any):
encrypted_message: List[Tuple[int]] = []
message_encoding: List[str] = []
identified_type: str = ""
if isinstance(message, Iterable):
if type(message) == str:
for char in message:
message_encoding.append(ord(char))
identified_type = "text"
#
elif isinstance(message, List):
for element in message:
if isinstance(element, int) or isinstance(element, float):
message_encoding.append("{0:b}".format(element))
identified_type = "number list"
#
#
#
elif isinstance(message, int) or isinstance(message, float):
message_encoding.append("{0:b}".format(message))
identified_type = "single number"
#
if identified_type == "":
return "it's unable to identify what you are trying to evaluate"
#
elif identified_type == "single number":
for number in message_encoding:
for bit in number:
# encrypt each bit
encrypted_message.append(self._perform_u_v(int(bit)))
#
#
return encrypted_message
#
def min_decrypt(self, ciphertext: List[Tuple[int]], sk: int) -> Any:
decrypted_message = ""
for element in ciphertext:
tmp_dec = (element[1] - sk * element[0]) % self._prime_q
if tmp_dec < self._prime_q / 2:
decrypted_message += "0"
else:
decrypted_message += "1"
#
#
return int(decrypted_message, 2)
#
def get_privateKey(self):
return self._privateKey
#
#
if __name__ == "__main__":
minimalistLWE = MinimalistLWE(97, 100)
minimalistLWE.gen_publicKey()
sk = minimalistLWE.get_privateKey()
encrypted_message = minimalistLWE.min_encrypt(90)
print(f"ciphertext: {encrypted_message}")
decrypted_message = minimalistLWE.min_decrypt(encrypted_message, sk)
print(f"plaintext again: {decrypted_message}")