Table 1. Classification of privacy protection technology for wearable device data.

Categories	Characteristics	Technologies	Representative Papers
Cryptography-based schemes	High security, but low efficiency	Homomorphic encryption	Wei et al. (2021) [20]
		Secure multi-party computation	Hua et al. (2018) [22]
Perturbation-based schemes	High calculation efficiency, but data accuracy can be biased	Anonymization	Liu et al. (2018) [24]
		Centered differential privacy	Yang et al. (2020) [27]
		Local differential Privacy	Li et al. (2020) [28]
			Wang et al. (2019) [29]