#include <stdio.h>
#include <string.h>

#define MAXLEN 256

int readfile(char* path, char* buf) {
  FILE* fd;
  fd = fopen(path, "r");
  if(!fd)
    return -1;
  fgets(buf, MAXLEN, fd);
  fclose(fd);
  return 0;
}

void applexor(char* msg, char* out) {
  int keys[] = {125, 137, 82, 35, 210, 188, 221, 234, 163, 185, 31};
  int i = 0;

  // Encrypt/decrypt (xor)
  for(i=0; msg[i] != '\0'; i++)
    out[i] = msg[i] ^ keys[i % 11];

  // If the previous char wasn't a null byte, we are likely encrypting not
  // decrypting, so add a null byte.
  if(out[i-1] != '\0') {
    out[i] = '\0' ^ keys[i % 11];
    i++;
  }

  // Append until we hit a multiple of 12
  for(; i%12 != 0; i++)
    out[i] = msg[i%strlen(msg)] ^ keys[i % 11];
  out[i] = '\0' ;
}

int main(int argc, char* argv[]) {
  char in[MAXLEN];
  char out[MAXLEN];
  if(argc == 1) {
    printf("Must provide path to file or a password to encrypt\n");
    return 1;
  }

  // If the file can't be opened, try to use the "path" as a password
  if(readfile(argv[1], in) == -1)
    strcpy(in, argv[1]);

  applexor(in, out);

  printf("%s\n", out);
  return 0;
}