Q2:

Post-Quantum Cryptography: One approach to combat quantum attacks on classical encryption is to transition to post-quantum cryptography (PQC). PQC algorithms rely on mathematical problems that are believed to be hard for both classical and quantum computers, such as lattice-based, code-based, and multivariate cryptography. Implementing PQC standards and protocols would ensure continued security even if quantum computers become powerful enough to break classical encryption.

Key Exchange and Rekeying: Another strategy is to focus on key exchange and rekeying mechanisms. In the event of a quantum computer breaking classical encryption, rekeying with fresh, post-quantum secure keys would mitigate the impact. This approach would require frequent key updates and efficient key management systems.

Hybrid Approach: A hybrid approach combines classical and post-quantum cryptography. This involves using classical encryption for initial communication and then transitioning to post-quantum encryption for sensitive data or long-term storage. This hybrid approach would provide a temporary buffer against quantum attacks while PQC standards are widely adopted.

Error-Correcting Codes: Improving error-correcting codes for quantum computers could also help combat quantum attacks. By reducing the number of physical qubits required for logical qubits, error-correcting codes could make it more difficult for quantum computers to achieve a sufficient number of qubits to break classical encryption.

Quantum-Resistant Hash Functions: Developing quantum-resistant hash functions would provide an additional layer of security. Hash functions are used in digital signatures and message authentication codes, and quantum-resistant variants would ensure the integrity of data even if quantum computers become powerful enough to break classical hash functions.

Monitoring and Adaptation: Finally, it's essential to continuously monitor the development of quantum computing and adapt cryptographic protocols and algorithms accordingly. This would involve staying informed about advancements in quantum computing, assessing their potential impact on cryptography, and updating cryptographic standards and practices as needed.