Time-Enabled and Verifiable Secure Search for Blockchain-Empowered Electronic Health Record Sharing in IoT

Table 1

Notation table.

	Description
	Keywords extracted from EHR
	The file containing the keyword
	All files containing the keyword
	Keyword generation time and trapdoor authorization time
	State ciphertext and set of state ciphertext
	Symmetric key ciphertext
	EHR ciphertext
	Proof for the verification of the search result
	The search trapdoor of
	Searched ciphertext and set of searched ciphertext
	a pseudorandom permutation and the inverse permutation
	An empty map, map state, map key, and a counter
	The version information about the current encrypted file
	An encrypted index containing the keyword