# A Survey on Recent Advanced Research of CPS Security
## 3 Reviews
### Attestation  
Attestation is defined as trustworthy evidence or proof of something. In the case of a cybersecurity system, it means a user can be confident about what they are receiving from a device. Researchers have proposed effective attestation schemes for IoT devices and designed new attestation protocols. SEDA [122] was the first attestation scheme for device swarms and leverages the common assumption to block physical attacks. It utilizes two new attestation architectures for embedded systems, SMART [151] and TrustLite [152], to implement two concrete instantiations, and its efficiency compared to traditional attestation was shown. With the implementations and simulations of large swarms with up to 1,000,000 devices, the results indicate that SEDA performs better than attesting each device separately. [PERSON] et al. [64] proposed a remote attestation scheme, boot attestation, which is particularly considerable for lightweight and resource-limited embedded devices. In boot attestation, software integrity measurements are immediately authenticated during boot instead of working in a secure environment, thus reducing the traditional requirements for cryptography and storage. They also described extensions for key provisioning and attestation towards untrustworthy third-party verifiers to increase practicality and completeness. US-AID [23] is an attestation scheme, particularly for autonomous and dynamic networks of IoT devices. US-AID combines continuous in-network attestation with a key exchange mechanism and Proofs-of-non-Absence to verify overall network integrity and effectively detects disconnecting physical attacks. With proof-of-concept implementations on autonomous drone swarms and extensive simulations, US-AID demonstrates its advantages in terms of energy and run-time. Current trigger-action platforms will be compromised if the OAuth tokens are leaked and misused by an adversary. [PERSON] et al. [63] proposed a decentralized trigger-action platform (DTAP), which uses the security principle of decentralized action integrity. This platform contains an untrusted cloud service and multiple trusted user clients that use transfer tokens (XTokens) to automatically obtain a rule-specific token and transmit it to the cloud service for rule execution. The authors evaluate DTAP with various micro- and macrobenchmarks, and the evaluation shows that the additional latency in rule execution time is modest while reducing throughput by 2.5%. [PERSON] [124] proposed attestation schemes that work for large networks of embedded devices. These schemes detect remote malware infestations and physical and run-time attacks in different smart environments and autonomous systems. [PERSON] et al. [24] presented DIAT, a unique method that allows the identification of the accuracy of data in autonomous collaborative networks. DIAT utilizes data integrity attestation, modular attestation, and a new description of execution paths to make devices interact securely and efficiently even when some nodes are compromised. After testing a drone formation, the authors also evaluated the scheme in a simulation environment to determine its capability for large-scale systems. PAtt [125] is a framework that utilizes remote software attestation to verify the integrity of physical processes controlled by the programmable logic controller (PLC). PAtt monitors minor changes in operation sequences to remotely verify the integrity of the control logic without a traditional trust anchor. The authors realized the proposed system on a controlled robot arm and detected PLC logic changing and spoofed sensor reading attacks with 97% accuracy. MTRA [131] is a multiple-tier remote attestation protocol that considers both TPM-enabled IoT devices and IoT devices that cannot support TPMs. It adopts a one-way hash chain to defend against wormhole attacks as well as rainbow attacks. Additionally, it deploys an online-offline notification mechanism to protect devices from time-of-check-to-time-of-use attacks assisted by the memory randomization technique.