-rw-r--r-- 726 cryptattacktester-20231020/bruteforce2_cost.cpp raw
#include <cassert>
#include "index_cost.h"
#include "bit_vector_cost.h"
#include "bruteforce2_cost.h"

using namespace std;

bigint bruteforce2_cost(const vector<bigint> &params,const vector<bigint> &attackparams)
{
  bigint n = params.at(0);
  bigint k = params.at(1);
  bigint w = params.at(2);
  bigint iters = attackparams.at(0);
  bigint cost = 0;
  for (bigint v = 0;v <= w;++v) {
    bigint binkv = binomial(k,v);
    iters -= binkv;

    for (bigint u = 1;u <= v;++u)
      cost += binomial(k-v+u,u)*(n-k); // adding vectors
    cost += binkv*bit_vector_hamming_weight_isnot_cost(n-k,w-v);
    cost += binkv*(n+v+2*(n-k));

    assert(iters >= 0);
    if (iters == 0) break;
  }
  assert(iters == 0);
  return cost;
}