Table 2 System Parameters and Definitions for malicious insider and TPA

Q_m = (q_m, f_m)

Query posed by a malicious insider

Q_m

Malicious attacker

T_I

Bounded time interval

(γ^Φ, β).

Prediction of the malicious attacker against protected data (queries and answers)

γ^Φ

Protected data comprising of query and answers

Z _j

The malicious insider entry

Z_j ∉ T_I

Unsuccessful attempt

Z _j  ∈ T _I

Successful attempt

Δq_a = f_a(q_a)

Response from TPA for malicious insider to authenticate itself

β = f_a(q_a)

Successful prediction of malicious insider