A Lightweight Attribute-Based Security Scheme for Fog-Enabled Cyber Physical Systems

Algorithm 6

Final secret key update.

1: Input: Shared attribute set.

2: Output: New final secret key .

3: If the attributes are the same, the previous computations over attributes are considered.

4: Else, perform calculations for attributes from to .

5: Compute secret number using Equation (8).

6: Next, compute :

where polynomial has been computed over attributes in Equation (9).

7: Pick two random numbers and then compute using Equation (10).

8: Next, compute secret key component using Equation (11).