## 2 Background and the Related Work  
### Background  
The integration of encryption techniques into SDN has attracted significant attention due to the increasing demand for robust security frameworks [11]. The evolution of digital communication requires advanced encryption techniques. The decoupling of the control and data planes in SDN provides centralized network management, scalability, and flexibility. However, the inherent architecture introduces vulnerabilities, which require robust encryption mechanisms to protect data integrity and confidentiality.  
Traditional algorithms such as the advanced encryption standard (AES), the data encryption standard (DES), and Rivest-Shamir-Adleman (RSA), have limitations. AES and DES are vulnerable to brute-force attacks when these algorithms are implemented as standalone encryption techniques, and RSA is impractical for large datasets due to their complexity [12; 13]. Hybrid encryption, which combines the strengths of both symmetric and asymmetric cryptography, is more suitable for high-security applications because it balances security and efficiency.  
[PERSON] [14] reviewed encryption techniques, access control, governance, compliance, and threat mitigation in multi-cloud environments. The author highlighted methodologies such as secure multiparty computation and ISO/IEC 27001 certification for regulatory compliance and cyber risk mitigation.  
[PERSON] et al. [15] highlighted that encryption practices are motivated by certain regulatory frameworks. On one hand, the U.S., with its federal and state laws, finds some common balance between security and privacy, influenced by the standards and sector-specific regulations established by the National Institute of Standards and Technology (NIST). On the other hand, the European Union insists through general data protection regulation (GDPR) that privacy is a fundamental right protected by the European Union Agency for Cybersecurity (ENISA) standards.  
[PERSON] et al. [16] illustrated that encryption maintains the confidentiality of data in an industrial control system network, but it creates difficulties in troubleshooting. Hence, industrial control system security should prioritize availability and integrity with an emphasis on authentication and integrity over complete encryption. [PERSON] et al. [17] concluded that combining AES-256 encryption with an ML-based intrusion prevention system (IPS) on open-source programmable logic controller platforms increases protection from cyber threats.  
[PERSON] et al. [18] presented an innovative hybrid approach that combines fully homomorphic encryption and secure hash algorithm-3 (SHA-3) to enhance data confidentiality, integrity, and processing efficiency. It tackles key management challenges and vendor limitations in cloud environments.  
[PERSON] et al. [19] highlighted the advances in attribute-based searchable encryption for enhancing security, efficiency, and flexibility in encrypted data searching. This includes policy hiding, computational outsourcing, and online/offline mechanisms, while bringing to light the integration of traceability, retractability, and future directions such as quantum attack resilience and parallel computing.  
Legacy networking has limitations with respect to the implementation of encryption mechanisms, key management, and resistance to vulnerabilities. Addressing these limitations in a traditional setup is complicated. In contrast, SDN offers a better prospect for implementing robust techniques to counter these challenges by virtue of its dynamic and programmability nature.