## 4 Applicability on Performance-Constrained Platforms
### IoT Systems  
IoT systems encompass a wide range of applications, from modern smart home sensors to devices embedded in critical infrastructure like power grids, traffic control, and water supply systems [55]. These are often devices that are installed for extended periods.  
The NIST uses the ARM Cortex M4 platform as a representative for embedded systems, whereas many IoT systems rely on processors with significantly lower performance capabilities (less RAM, slower processors). According to [55], Falcon is a better choice for implementing post-quantum (PQ) digital signatures on IoT platforms with limited RAM (up to about 64 KB). A similar conclusion is drawn by the authors of [56], where PQ signatures are verified on systems with 8 KB of RAM (ARM Cortex M3), including Sphincs+, thus making all three algorithms applicable for IoT in a broader context. Sphincs+ is also applicable for ARM Cortex M3 [36].  
The authors circumvented the problem of oversized keys by streaming the keys into memory in parts and performing operations accordingly [56]. In general, in lattice-based signatures like Dilithium2 and Falcon-512, hashing constitutes a significant portion of the computational load, accounting for 65% and 36% of it, respectively. Similarly, in hash-based signature schemes like Sphincs-Sha256-128s-Simple and Sphincs-Sha256-128f-Simple, hashing operations represent an even larger share, corresponding to 90% and 88%, respectively. Both types of schemes would benefit more from hardware-accelerated hashing.  
In a research paper [57], the authors presented a post-quantum secure multi-party collaborative signature scheme that enhances detectability in Industrial Internet of Things (IIoT) settings. This approach addresses both fairness and privacy protection issues that are commonly found in conventional IIoT security mechanisms. To validate the practicality of this Dilithium-based protocol, the authors developed and tested a prototype to assess its performance.  
In their research [58], the authors showed the FPGA implementations of all three round-3 parameter sets for Dilithium, targeting the low-end Artix-7 platform. Their design adhered to a universal objective: it achieved low latency in comparison to other post-quantum secure signature algorithms, while maintaining a small area footprint. This dual advantage makes the use of Dilithium viable in a range of low-cost and resource-constrained environments, including IoT.  
A paper [59] investigated an area-efficient FPGA implementation of Sphincs+, a post-quantum hash-based signature scheme. By leveraging resource sharing in a compact hardware solution, the authors successfully adapted Sphincs+ for resource-constrained systems like IoT devices and nano-satellites.  
Another paper [60] compared the suitability of Falcon and Dilithium signature schemes for IoT applications, focusing on verification performance and transmission cost. Falcon emerged as the more efficient choice in terms of both speed and resource utilization, particularly in FPGA environments. This advantage is likely to extend to ASICs, suggesting a better time-area product for Falcon. However, Dilithium presents an advantage in scenariosrequiring frequent key generation or client-side signing due to its lower complexity in these operations. Thus, while Falcon offers superior verification and transmission efficiencies, Dilithium may be preferable for applications with specific key management requirements.