Data Authentication for Wireless Sensor Networks with High Detection Efficiency Based on Reversible Watermarking

Algorithm 2

Encoding

Input: original data stream S

Output: stream

while (Stream S is not over) do

1. if (spflag ==0)

2. G ⟵ S₁S_i−1

3. .

4. for k ⟵1 to i−1 do

5. H_k ⟵ hash(G_k, d)

6.  ⟵ ( + G_k) /2

7. end for

8. H=H₁⊕H₂⊕H_m//H ={W_r, 1 ≤ r ≤ d & W_r =0||1};

9. else if (spflag ==1)

10. C ⟵ S₁S₂S_i−1

11. for j ⟵1 to i−1 do

12.  ⟵ C_j −

13. pe' ⟵ pe × 2 + W_j

14. C_j' ⟵ + pe'

15.  ⟵ ( + C_j) /2

16. if (md5(C_j') % m ==0) //C_j' is a fake synchronization point;

17. C_j' ⟵ fcb(a) + C_j' //Add fcb(a) to the flag check bit of C_j';

18. else

19. b ⟵ rand() & b ≠ a//b is a random number not equal to a;

20. C_j' ⟵ fcb(b) + C_j'

21. end if

22. S_j' ⟵ C_j'

23. end for

24. end if

25. end while