GCHQ CanYouCrackIt Stage 3 - C representation of keygen

// licence file to contain
// gchqcyberwinAAAABBBBCCCC
int main(int argc, char **argv) {
    char buf[0x18];
    long *longPtr = NULL;

    if(argc != 1)
    {
        // display usage and exit
    }

    memset(buf, 0, 0x18); // clear buffer

    FILE *in = fopen("license.txt", "r");
    fscanf(in, "%s", buf);  // buffer overflow vulnerability - tut tut!
    fclose(in);

    &longPtr = &buf;
    if(*longPtr != 0x71686367) // first 4 bytes = 'gchq'?
    {
        // error & exit
    }

    if(strcmp(crypt(buf[4], "hq"), "hqDTK7b8K2rvw")) { //hash next 8 bytes and compare with our hash
        // invalid code - exit
    }


    // everything has checked out - construct URL
    // of format /hqDTK7b8K2rvw/XX/XX/XX/key.txt
    // where XX, XX, XX are taken from next 3x four bytes of licence and produced as HEX
    // connect to hostname supplied on command line

}