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key_reconciliation.py
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key_reconciliation.py
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from qiskit import QuantumCircuit, transpile
from qiskit_aer import AerSimulator
import hashlib
import random as rand
def key_reconciliation(alice_key, bob_key, block_size=1, rounds=4):
fixed_key = cascade_error_correction(alice_key, bob_key, block_size, rounds)
final_key = privacy_amplification(fixed_key)
return fixed_key, final_key
def cascade_error_correction(alice_key, bob_key, initial_block_size=1, rounds=4):
key_length = len(alice_key)
bob_key = bob_key.copy() # Create a copy to avoid modifying the original
for round in range(rounds):
block_size = initial_block_size * (2 ** round)
for i in range(0, key_length, block_size):
alice_block = alice_key[i:i+block_size]
bob_block = bob_key[i:i+block_size]
if parity(alice_block) != parity(bob_block):
error_index = binary_search_error(alice_block, bob_block)
bob_key[i + error_index] = alice_key[i + error_index]
# Cascade effect
if round > 0:
cascade_to_previous_blocks(alice_key, bob_key, i + error_index, initial_block_size)
return bob_key
def parity(block):
return sum(block) % 2
def binary_search_error(alice_block, bob_block):
start, end = 0, len(alice_block) - 1
while start < end:
mid = (start + end) // 2
if parity(alice_block[:mid+1]) != parity(bob_block[:mid+1]):
end = mid
else:
start = mid + 1
return start
def cascade_to_previous_blocks(alice_key, bob_key, error_index, min_block_size):
block_size = len(alice_key) // 2
while block_size >= min_block_size:
block_start = (error_index // block_size) * block_size
alice_block = alice_key[block_start:block_start+block_size]
bob_block = bob_key[block_start:block_start+block_size]
if parity(alice_block) != parity(bob_block):
new_error_index = binary_search_error(alice_block, bob_block)
bob_key[block_start + new_error_index] = alice_key[block_start + new_error_index]
block_size //= 2
def privacy_amplification(key):
# hash
seed = ''.join(map(str, key))
hash_object = hashlib.sha256(seed.encode())
hashKey = hash_object.digest()
binKey = bin(int.from_bytes(hashKey, 'little'))[2:]
return [int(bit) for bit in str(binKey)]