# SoK: Delegated Security in the Internet of Things
## 6 Discussion
### Proposed Countermeasures and Mitigations  
This section is dedicated to the discussion of the countermeasures proposed by the authors of the reviewed papers, which aim to prevent various attacks and ensure the fundamental security properties (CIA). In order to ensure the confidentiality and integrity of the information, several systems implement the TLS protocol directly [28; 30; 33; 96; 97; 98] or use it as a basis for the DTLS handshake protocol [21; 22; 38; 42; 47; 48; 85; 99; 100; 101; 102]. DTLS not only secures transmitted data and provides strong authentication inherited from TLS, but also helps accelerate system processes. To counter long-term attacks, dynamic monitoring is proposed [103], where the system observes device activity during runtime. Based on this observation, it can detect suspicious behaviour and impose restrictions if necessary. Additionally, various combinations of lightweight cryptographic protocols have been suggested to ensure data protection, each offering specific advantages and trade-offs depending on the applicationcontext [8; 15; 94; 104]. Furthermore, many systems adopt security mechanisms such as cryptographic hashing and multi-factor authentication to enhance data protection. Decentralised architectures, including blockchain-based solutions, are also widely implemented to ensure tamper resistance, transparency, and trust [22; 46; 49; 61; 105; 106]. According to the results of our analysis, DoS attacks that lead to SPoF pose the greatest risk to system availability. Delegation, by design, helps reduce the success rate of DoS attacks by shifting the adversary's target from a resource-constrained device to a more capable delegate. Since a delegate is assumed to have greater computational and communication resources, it is generally expected to withstand such attacks. However, in practice, a delegate may be more powerful than other devices in the system, but still not strong enough to resist a determined adversary. If an adversary succeeds in corrupting a delegate, this can result in a SPoF scenario that compromises the availability of the entire system. In order to mitigate risks associated with a SPoF, several countermeasures have been implemented in the evaluated systems. These include accepting requests only from already authenticated users [23; 34; 38; 43; 45; 47; 97; 101; 102], deploying multiple proxies instead of a single delegate to distribute the load and reduce reliance on a single point [20], and implementing decentralised or redundant architectures, often based on blockchain technology [8; 32; 33; 37; 45; 61; 107]. These strategies significantly reduce or even eliminate the impact of successful DoS attacks, thereby enhancing system availability. However, despite their undeniable advantages, for example, blockchain-based approaches are not always applicable for resource-constrained devices, which prevents them from being used for typical systems such as smart home, which mostly consists of \"weak\" devices. Summarising the results of our research and discussion, the following conclusions are drawn:  
* Most existing studies do not provide formalised models of their proposed solutions, with the notable exception of those within the cryptographic delegation application domain. * The security analysis of the proposed delegation solutions is often either completely absent or limited to a narrow scope, typically considering only a single type of adversary. In most cases, the evaluated adversary is weak and external, while stronger internal threats or more complex attack scenarios are largely overlooked. * Most of the proposed solutions meet confidentiality and integrity requirements when evaluated against specific types of adversaries. However, they often do not provide sufficient system availability, especially under DoS attacks or in the presence of a potential SPoF. * Solutions that provide robust and comprehensive security guarantees are frequently tailored for environments with ample computational and network resources.