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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main(int argc, char* argv[]) {
FILE* mess = fopen(argv[1], "r");
FILE* pad = fopen(argv[2], "r+");
FILE* critt = fopen(argv[3],"w");
fseek(mess, 0L, SEEK_END);
long mess_size = ftell(mess);
rewind(mess);
fseek(pad, 0L, SEEK_END);
long pad_size = ftell(pad);
fseek(pad, (pad_size - mess_size), SEEK_SET);
int i = 1;
char a, b;
while(i != EOF) {
i = fscanf(mess, "%c", &a);
fscanf(pad, "%c", &b);
if(i != EOF) {
fprintf(critt, "%c", a^b);
}
}
/* The truncate function "rosicchia" la parte di chiave utilizzata */
ftruncate(fileno(pad), (pad_size - mess_size));
fseek(pad, 0L, SEEK_END);
long new_pad_size = ftell(pad);
fclose(mess);
fclose(pad);
fclose(critt);
printf("Message length is %li bytes \n", mess_size);
printf("Pad length was %li bytes \n", pad_size);
printf("Pad length is now %li bytes \n", new_pad_size);
printf("Pad length should now be %li bytes \n", (pad_size - mess_size));
exit(EXIT_SUCCESS);
}
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