Algorithm 3: IP Marks Authentication algorithm

Input: (i) Position $P_n$ and ${L^{\prime }}_n$ (ii) Constraint function $H{W}_{xy}$ Output: (i) Legal user (ii) Illegal user /* To satisfy the condition $H{W}_{xy}$, ${L^{\prime }}_n$ and $P_n$ are compared, and then judge whether ${L^{\prime }}_n$ is legal or not */ /* ${L^{″}}_n$ represents the element that satisfies the condition of $H{W}_{xy}$,$S_n$ represents the same element */ 1: Calculate ${L^{″}}_n$ according to ${L^{\prime }}_n$ and $H{W}_{xy}$ /* Compare each of $S_n$ and $P_n$ elements */ 2: gets(${L^{″}}_n$); gets($P_n$); for (i = 0; i < sizeof(${L^{″}}_n$) / sizeof(${L^{″}}_n\left[0\right]$); i++) {    for (j = 0; j < sizeof($P_n$) / sizeof($P_n\left[0\right]$); j++)     {       if (${L^{″}}_n\left[\mathrm{i}\right]$==$P_n\left[\mathrm{i}\right]$)       {        Store ${L^{″}}_n$ in $S_n$;       }     }   } 3: End for /* Evaluate the similarity */ 4: If (sizeof($S_n$) / sizeof($P_n$) ≥ 0.8) 5: Output: Legal user 6: else if (sizeof($S_n$) / sizeof($P_n$) < 0.8) 7: Output: Illegal user;