george0papasotiriou/cve-2026-22020-weak-seed-in-quantum-key-distribution-error-correctionPython PoC demonstrating CVE-2026-22020: exploitable weak seed in quantum key distribution privacy amplification, reducing final key entropy.
# qkd_weak_seed.py - Simulated QKD privacy amplification with weak seed
import hashlib, os, time
def privacy_amplification(sifted_key, seed):
# Weak: seed derived from current time, predictable
if seed is None:
seed = str(time.time()).encode()
return hashlib.sha256(seed + sifted_key).digest()
# In real QKD, an eavesdropper who knows the seed can reduce the final key's entropy.
weak_seed = str(time.time()).encode()
final_key = privacy_amplification(b'raw_key', weak_seed)
print("Final key with weak seed generated.")
A QKD system uses a predictable seed (e.g., system time) during the privacy amplification phase. An attacker who can guess the seed can significantly reduce the final key’s effective entropy, potentially breaking the security of the quantum channel.
Run the simulation:
python qkd_weak_seed.py
The output demonstrates the use of a predictable seed.