Secure KNN Classification Scheme Based on Homomorphic Encryption for Cyberspace

Table 1

Notations.

Symbols	Description
	Known category sample
	Standardized data sample
	Category label of known category sample
	Sample to be classified
	Category label of sample to be classified
	The j-th feature index of the i-th sample
	Public and private key
	Similarity
	Euclidean distance
	Pearson correlation coefficient
	Cosine similarity