## 5 Discussion  
As we discussed, in the future, when quantum computers could represent an issue, post-quantum encryption will depend on robust and computationally secure methods to protect sensitive data. The standardization of algorithms by NIST has led to the attention and acceptance of CRYSTALS-Kyber, CRYSTALS-Dilithium, and Falcon. However, NIST advises CRYSTALS-Dilithium as the preferred option for digital signatures and CRYSTALS-Kyber as the first PQC key exchange technique. Lattice-based cryptography issues are at the core of CRYSTALS-Kyber, CRYSTALS-Dilithium, and Falcon.  
In our results in comparing post-quantum cryptographic solutions, the combination of Kyber 512 and Dilithium 3 proved superior when balancing key generation time, operational performance, and security. The performance of RSA declined significantly with larger key sizes; however, Falcon was efficient in operating times but has long key creation times (up to 10,016.76 ms for Falcon 512), making it unsuitable for rapid key setup. Kyber 512 and Dilithium 3 provide an optimal option, with a total key generation time of 124.93 ms, encapsulation and signature at 359.29 ms, and decapsulation and verification at 171.83 ms.  
Despite their robustness, there remains a concern that these algorithms may eventually expose vulnerabilities, emphasizing the need for continuous scrutiny in the field. QKD, on the other hand, is secure based on the principles of quantum mechanics. This raises the question of whether using technically safe authentication methods could negatively impact the security of QKD. It is crucial to clarify that the authentication strategy used in QKD only needs to be temporarily secure. Therefore, there is often no need for concern regarding the computational security of the encapsulation and authentication procedures.  
If the encapsulation or authentication procedures were compromised during the use of the QKD protocol, a man-in-the-middle attack could be executed successfully. However, even if such a breach occurred after the key exchange, the security of the quantum-distributed symmetric encryption keys would remain intact. In the rare instance that the encapsulation and authentication methods employed in QKD become vulnerable to an attacker with significant computational resources, a straightforward countermeasure would be to update the algorithm to a more secure one. This could be achieved without ever placing the keys produced by QKD at risk.  
This shows the importance of flexibility and adaptability in cryptographic protocols. As computational power increases and new vulnerabilities are discovered, the ability to quickly update and improve encryption and authentication methods becomes crucial. The concept of forward secrecy (FS), also known as perfect forward secrecy (PFS), where past communications remain secure even if current keys are compromised, is particularly relevant here. By ensuring that each key exchange session is independently secure, we can protect the integrity of encrypted data over time.  
Moreover, the use of computationally secure encapsulation and authentication in QKD does not compromise its security, rendering privacy amplification unnecessary. This illustrates an appropriate justification for integrating post-quantum cryptographic methods with QKD, enhancing the overall security framework without introducing new vulnerabilities.