A Random Label and Lightweight Hash-Based Security Authentication Mechanism for a UAV Swarm

Algorithm 2

The iterative algorithm of SHA-256.

1: fordo

2: Logical function operation:

3: S0 = (A rightrotate 2)(A rightrotate 13)(a rightrotate 22);

4: Ma = (A and B)(A and C)(B and C);

5: t2 = S0 + Ma;

6: S1 = (E rightrotate 6)(E rightrotate 11)(E rightrotate 25);

7: Ch = (E and F)((not E) and G);

8: ;

9: Update each word:

10: H=G;

11: G=F;

12: F=E;

13: E = D + t1;

14: D = C;

15: C = B;

16: B = A;

17: A = t1 + t2;

18: Add the hash output of the message block to the existing hash output:

19: h0 = h0 + A;

20: h1 = h1 + B;

21: h2 = h2 + C;

22: h3 = h3 + D;

23: h4 = h4 + E;

24: h5 = h5 + F;

25: h6 = h6 + G;

26: h7 = h7 + H;

27: Output the final hash value (big-endian):

28: digest = hash = h0 append h1 append h2 append h3 append h4 append h5 append h6 append h7;

29:end for

30: return digest;