int main(int argc, char const *argv[])
{
if (argc > 1){
if (argc == 3 && !strcmp(argv[1], "setup")){
global_broadcast_params_t gbs;
//Global Setup
int n = atoi(argv[2]);
setup_global_broadcast_params(&gbs, n);
FILE * file;
file = fopen("/tmp/gbs2.txt" , "w");
int i = 0, t;
//print n
fprintf(file, "%d\n", n);
//print g
fprintf(file, "%s\n", PUBLIC_G);
//print gs[i]
for (i=0; i < 2*n; i++){
if (i==n)
continue;
char* s = (char*) malloc(MAX_ELEMENT_LEN);
t = element_snprint(s, MAX_ELEMENT_LEN, gbs->gs[i]);
fprintf(file, "%s\n", s);
free(s);
}
fclose(file);
store_gbp_params("/tmp/gbs.txt", gbs);
FreeGBP(gbs);
return 0;
}
else if (argc == 2 && !strcmp(argv[1], "restore")){
global_broadcast_params_t gbs;
//Global Setup
restore_global_broadcast_params2(&gbs);
return 0;
}
else if (argc == 3 && !strcmp(argv[1], "revoke")){
update_after_revocation(argv[2]);
return 0;
}
}
fprintf(stderr, "Run with ./mainbgw [task] [Other parameter]\n");
fprintf(stderr, "For example ./mainbgw setup 16\n");
return 1;
}
//Called in file encryption function to generate C0,C1,C0',C1' and EK
//returns CT,EK
void EK_CT_generate(char *gamma, int *shared_users, int num_users, unsigned char *pps, ct CT, element_t EK, char *t_str)
{
global_broadcast_params_t gbs;
element_t t;
int j;
//Global Setup of gbs params
setup_global_broadcast_params(&gbs, pps);
element_set_str(gbs->gamma, gamma, PBC_CONVERT_BASE); //it is important to set user gamma here else a random value will be used
//pick a random value of t from Zr
element_init_Zr(t, gbs->pairing);
element_random(t);
element_snprint(t_str,MAX_ELEMENT_LEN,t);
//compute C0=g^t
element_init(CT->OC0, gbs->pairing->G1);
element_pow_zn(CT->OC0, gbs->g, t);
//compute C1=(g^gamma)x(g[num_users+1-j]) for j in all shared users
element_init(CT->OC1, gbs->pairing->G1);
element_pow_zn(CT->OC1, gbs->g, gbs->gamma); //at this step C1 = g^gamma = v as given in paper
for(j=0;j<num_users;j++)
element_mul(CT->OC1, CT->OC1, gbs->gs[(gbs->num_users)-shared_users[j]]);
element_pow_zn(CT->OC1, CT->OC1, t);
//Duplicate C0'=C0
element_init(CT->C0, gbs->pairing->G1);
element_set(CT->C0,CT->OC0);
//Duplicate C1'=C1
element_init(CT->C1, gbs->pairing->G1);
element_set(CT->C1,CT->OC1);
//COMPUTE EK = e(g[n], g[1])^(t)
element_init(EK, gbs->pairing->GT);
element_pairing(EK, gbs->gs[0],gbs->gs[gbs->num_users-1]); //at this step EK = e(g[1],g[n])
element_pow_zn(EK,EK,t); //EK = e(g[1],g[n])^t
//free the memory for global broadcast params
element_clear(t);
FreeGBP(gbs);
return;
}
