libdpf/examples/applications/keyword_pir.cpp

#include <cstdint>
#include <iostream>
#include <string>
#include <vector>

#include "dpf.hpp"
#include "dpf/app_flow.hpp"
#include "dpf/app_plans.hpp"

// Two-server keyword PIR, the DPF step (Gilboa and Ishai, EUROCRYPT 2014).
// `eval_sequence_xor` folds the selected records into one XOR accumulator
// without materializing a bit vector.
//
//   c++ -std=c++17 -march=native -pthread -I include -I thirdparty \
//       examples/applications/keyword_pir.cpp
//   DPF_EXPERIMENT_DIR=/tmp/kw ./a.out   # optional CSV dump

namespace
{

using keyword = dpf::keyword<3, dpf::alphabets::lowercase_alpha>;

}  // namespace

int main()
{
    const std::vector<keyword> dict{keyword{"bat"}, keyword{"cat"},
        keyword{"dog"}, keyword{"pig"}};
    const std::vector<int> records{56, 12, 34, 78};

    auto [k0, k1] = dpf::make_dpf(keyword{"bat"}, dpf::bit::one);
    const int selected = dpf::eval_sequence_xor(k0, dict.begin(), dict.end(),
                            records)
        ^ dpf::eval_sequence_xor(k1, dict.begin(), dict.end(), records);
    if (selected != 56)
    {
        std::cerr << "keyword hit\n";
        return 1;
    }

    auto [m0, m1] = dpf::make_dpf(keyword{"rat"}, dpf::bit::one);
    const int missing = dpf::eval_sequence_xor(m0, dict.begin(), dict.end(),
                            records)
        ^ dpf::eval_sequence_xor(m1, dict.begin(), dict.end(), records);
    if (missing != 0)
    {
        std::cerr << "keyword miss\n";
        return 1;
    }

    {
        constexpr std::size_t depth = dpf::utils::bitlength_of<keyword>::value;
        if (int rc = dpf::app::run_measured("keyword_pir",
                dpf::protocol::keyword_pir_compose_plan(0, depth), 2))
            return rc;
    }

    std::cout << selected << "\n";
    return 0;
}