Quantum Key Distribution: Security Analysis of BB84 and E91 Under Realistic Attack Models

Sammanfattning

Cryptography is crucial to protect sensitive data. Traditional cryptography relies on mathematical difficulty to secure valuable data against intruders. However, with the rise of quantum computers, these assumptions are threatened as quantum computers can process information much faster. The security models need to be upgraded to withstand quantum computers. RSA and ECC, two common asymmetric cryptosystems, have been upgraded using post-quantum cryptography (PQC). Another solution might be to leverage the principles of quantum mechanics to ensure secure communication. The most common application of quantum cryptography is quantum key distribution (QKD), which solves the key exchange problem using quantum physics, complementing conventional cryptographic techniques by enabling secure key generation, while classical methods remain necessary for authentication and protocol implementation. QKD is secure in theory, but practical implementations often differ from theory due to imperfect devices. An intruder can find loopholes and vulnerabilities to attack the QKD systems and jeopardize its security. In this thesis, current knowledge of these attacks has been reviewed and simulated on two different QKD protocols. The simulations highlight the importance of researching the attacks and implementing countermeasures.