-rw-r--r-- 1869 cryptattacktester-20230614/bruteforce2.cpp raw
#include "decoding.h"
#include "bit_vector.h"
#include "index.h"
#include "bruteforce2.h"

using namespace std;

vector<bit> bruteforce2(
  const vector<bit> &bits,
  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);

  auto inputs = decoding_deserialize(bits,params);
  auto pk = inputs.first;
  auto ct = inputs.second;

  vector<bit> result(n);

  for (bigint v = 0;v <= w;++v) {
    if (iters <= 0) break;

    vector<bigint> positions;
    vector<vector<bit>> ctHguess;
    ctHguess.push_back(ct);

    vector<bit> ctplus = ct;
    for (bigint j = 0;j < v;++j) {
      positions.push_back(n-k+j);
      for (bigint i = 0;i < n-k;++i)
        ctplus.at(i) ^= pk.at(i).at(positions.at(j)-(n-k));
      ctHguess.push_back(ctplus);
    }

    while (iters > 0) {
      --iters;

      bit mismatch = bit_vector_hamming_weight_isnot(ctHguess.at(v),w-v);

      for (bigint j = 0;j < n;++j)
        result.at(j) &= mismatch;
      for (bigint j = 0;j < v;++j)
        result.at(positions.at(j)) = result.at(positions.at(j)).orn(mismatch);
      for (bigint j = 0;j < n-k;++j)
        result.at(j) = result.at(j) | ctHguess.at(v).at(j).andn(mismatch);
  
      bigint j;
      for (j = v-1;j >= 0;--j) {
        positions.at(j) += 1;
        if (positions.at(j) <= n-v+j) {
          for (bigint i = 0;i < n-k;++i)
            ctHguess.at(j+1).at(i) = ctHguess.at(j).at(i) ^ pk.at(i).at(positions.at(j)-(n-k));
          while (++j < v) {
            positions.at(j) = positions.at(j-1)+1;
            for (bigint i = 0;i < n-k;++i)
              ctHguess.at(j+1).at(i) = ctHguess.at(j).at(i) ^ pk.at(i).at(positions.at(j)-(n-k));
          }
          break;
        }
      }
      if (j < 0) break;
    }
  }

  return result;
}