Algorithm 3: Data Querying.

Input: $M_{A-HFB}$;

Step 1: query

A chooses a random number $k_{A1}$;

$M_{A-HFB}=(I{D}_A\parallel T_{A-HFB}\parallel Keywords)$;

call function $Sign(M_{A-HFB},d_A,k_{A1})$, return $(r_{A1},s_{A1})$;

send $M_{A-HFB}, (r_{A1},s_{A1})$ to HFB

Step 2: return

Upon receiving; check whether $T_{NOW}-T_{A-HFB}\le \tau$;

call function $Verify(z_{A1}{}^{\prime },r_{A1},s_{A1})$, return result;

if$T_{NOW}-T_{A-HFB}\le \tau$then

if result = “valid” then

call chaincode “Querfile”, return Keyword-index table to A;

end

end