Authenticated Blind Issuing of Symmetric Keys for Mobile Access Control System without Trusted Parties

Table 4

Possible database contents of a Guard 𝒢_𝑗.

Status	User ID	Key	Valid time	Issuer
⟨𝒜⟩	ID𝒰1	𝒦𝒜𝒢	VT𝒰1	00
⟨𝒮⟩	ID𝒰2	𝒦𝒰2	VT𝒰2	ID𝒰1
⟨𝒮⟩	ID𝒰3	𝒦𝒰3	VT𝒰3	ID𝒰2
⟨𝒰⟩	ID𝒰4	𝒦𝒰4	VT𝒰4	ID𝒰1
⟨𝒰⟩	ID𝒰5	𝒦𝒰5	VT𝒰5	ID𝒰2
⟨𝒰⟩	ID𝒰6	𝒦𝒰6	VT𝒰6	ID𝒰3