Пример #1
0
    KeyGenerator::KeyGenerator(const EncryptionParameters &parms) :
        poly_modulus_(parms.poly_modulus()), coeff_modulus_(parms.coeff_modulus()), plain_modulus_(parms.plain_modulus()),
        noise_standard_deviation_(parms.noise_standard_deviation()), noise_max_deviation_(parms.noise_max_deviation()),
        decomposition_bit_count_(parms.decomposition_bit_count()), mode_(parms.mode()),
        random_generator_(parms.random_generator() != nullptr ? parms.random_generator()->create() : UniformRandomGeneratorFactory::default_factory()->create())
    {
        // Verify required parameters are non-zero and non-nullptr.
        if (poly_modulus_.is_zero())
        {
            throw invalid_argument("poly_modulus cannot be zero");
        }
        if (coeff_modulus_.is_zero())
        {
            throw invalid_argument("coeff_modulus cannot be zero");
        }
        if (plain_modulus_.is_zero())
        {
            throw invalid_argument("plain_modulus cannot be zero");
        }
        if (noise_standard_deviation_ < 0)
        {
            throw invalid_argument("noise_standard_deviation must be non-negative");
        }
        if (noise_max_deviation_ < 0)
        {
            throw invalid_argument("noise_max_deviation must be non-negative");
        }
        if (decomposition_bit_count_ <= 0)
        {
            throw invalid_argument("decomposition_bit_count must be positive");
        }

        // Verify parameters.
        if (plain_modulus_ >= coeff_modulus_)
        {
            throw invalid_argument("plain_modulus must be smaller than coeff_modulus");
        }
        if (!are_poly_coefficients_less_than(poly_modulus_, coeff_modulus_))
        {
            throw invalid_argument("poly_modulus cannot have coefficients larger than coeff_modulus");
        }

        // Resize encryption parameters to consistent size.
        int coeff_count = poly_modulus_.significant_coeff_count();
        int coeff_bit_count = coeff_modulus_.significant_bit_count();
        int coeff_uint64_count = divide_round_up(coeff_bit_count, bits_per_uint64);
        if (poly_modulus_.coeff_count() != coeff_count || poly_modulus_.coeff_bit_count() != coeff_bit_count)
        {
            poly_modulus_.resize(coeff_count, coeff_bit_count);
        }
        if (coeff_modulus_.bit_count() != coeff_bit_count)
        {
            coeff_modulus_.resize(coeff_bit_count);
        }
        if (plain_modulus_.bit_count() != coeff_bit_count)
        {
            plain_modulus_.resize(coeff_bit_count);
        }
        if (decomposition_bit_count_ > coeff_bit_count)
        {
            decomposition_bit_count_ = coeff_bit_count;
        }

        // Calculate -1 (mod coeff_modulus).
        coeff_modulus_minus_one_.resize(coeff_bit_count);
        decrement_uint(coeff_modulus_.pointer(), coeff_uint64_count, coeff_modulus_minus_one_.pointer());

        // Initialize public and secret key.
        public_key_.resize(coeff_count, coeff_bit_count);
        secret_key_.resize(coeff_count, coeff_bit_count);

        // Initialize evaluation keys.
        int evaluation_key_count = 0;
        Pointer evaluation_factor(allocate_uint(coeff_uint64_count, pool_));
        set_uint(1, coeff_uint64_count, evaluation_factor.get());
        while (!is_zero_uint(evaluation_factor.get(), coeff_uint64_count) && is_less_than_uint_uint(evaluation_factor.get(), coeff_modulus_.pointer(), coeff_uint64_count))
        {
            left_shift_uint(evaluation_factor.get(), decomposition_bit_count_, coeff_uint64_count, evaluation_factor.get());
            evaluation_key_count++;
        }
        evaluation_keys_.resize(evaluation_key_count);
        for (int i = 0; i < evaluation_key_count; ++i)
        {
            evaluation_keys_[i].resize(coeff_count, coeff_bit_count);
        }

        // Initialize moduli.
        polymod_ = PolyModulus(poly_modulus_.pointer(), coeff_count, coeff_uint64_count);
        mod_ = Modulus(coeff_modulus_.pointer(), coeff_uint64_count, pool_);
    }
    Evaluator::Evaluator(const EncryptionParameters &parms, const EvaluationKeys &evaluation_keys) :
        poly_modulus_(parms.poly_modulus()), coeff_modulus_(parms.coeff_modulus()), plain_modulus_(parms.plain_modulus()),
        decomposition_bit_count_(parms.decomposition_bit_count()), evaluation_keys_(evaluation_keys), mode_(parms.mode())
    {
        // Verify required parameters are non-zero and non-nullptr.
        if (poly_modulus_.is_zero())
        {
            throw invalid_argument("poly_modulus cannot be zero");
        }
        if (coeff_modulus_.is_zero())
        {
            throw invalid_argument("coeff_modulus cannot be zero");
        }
        if (plain_modulus_.is_zero())
        {
            throw invalid_argument("plain_modulus cannot be zero");
        }
        if (decomposition_bit_count_ <= 0)
        {
            throw invalid_argument("decomposition_bit_count must be positive");
        }
        if (evaluation_keys_.count() == 0)
        {
            throw invalid_argument("evaluation_keys cannot be empty");
        }

        // Verify parameters.
        if (plain_modulus_ >= coeff_modulus_)
        {
            throw invalid_argument("plain_modulus must be smaller than coeff_modulus");
        }
        if (!are_poly_coefficients_less_than(poly_modulus_, coeff_modulus_))
        {
            throw invalid_argument("poly_modulus cannot have coefficients larger than coeff_modulus");
        }

        // Resize encryption parameters to consistent size.
        int coeff_count = poly_modulus_.significant_coeff_count();
        int coeff_bit_count = coeff_modulus_.significant_bit_count();
        int coeff_uint64_count = divide_round_up(coeff_bit_count, bits_per_uint64);
        if (poly_modulus_.coeff_count() != coeff_count || poly_modulus_.coeff_bit_count() != coeff_bit_count)
        {
            poly_modulus_.resize(coeff_count, coeff_bit_count);
        }
        if (coeff_modulus_.bit_count() != coeff_bit_count)
        {
            coeff_modulus_.resize(coeff_bit_count);
        }
        if (plain_modulus_.bit_count() != coeff_bit_count)
        {
            plain_modulus_.resize(coeff_bit_count);
        }
        if (decomposition_bit_count_ > coeff_bit_count)
        {
            decomposition_bit_count_ = coeff_bit_count;
        }

        // Determine correct number of evaluation keys.
        int evaluation_key_count = 0;
        Pointer evaluation_factor(allocate_uint(coeff_uint64_count, pool_));
        set_uint(1, coeff_uint64_count, evaluation_factor.get());
        while (!is_zero_uint(evaluation_factor.get(), coeff_uint64_count) && is_less_than_uint_uint(evaluation_factor.get(), coeff_modulus_.pointer(), coeff_uint64_count))
        {
            left_shift_uint(evaluation_factor.get(), decomposition_bit_count_, coeff_uint64_count, evaluation_factor.get());
            evaluation_key_count++;
        }

        // Verify evaluation keys.
        if (evaluation_keys_.count() != evaluation_key_count)
        {
            throw invalid_argument("evaluation_keys is not valid for encryption parameters");
        }
        for (int i = 0; i < evaluation_keys_.count(); ++i)
        {
            BigPoly &evaluation_key = evaluation_keys_[i];
            if (evaluation_key.coeff_count() != coeff_count || evaluation_key.coeff_bit_count() != coeff_bit_count ||
                evaluation_key.significant_coeff_count() == coeff_count || !are_poly_coefficients_less_than(evaluation_key, coeff_modulus_))
            {
                throw invalid_argument("evaluation_keys is not valid for encryption parameters");
            }
        }

        // Calculate coeff_modulus / plain_modulus.
        coeff_div_plain_modulus_.resize(coeff_bit_count);
        Pointer temp(allocate_uint(coeff_uint64_count, pool_));
        divide_uint_uint(coeff_modulus_.pointer(), plain_modulus_.pointer(), coeff_uint64_count, coeff_div_plain_modulus_.pointer(), temp.get(), pool_);

        // Calculate (plain_modulus + 1) / 2.
        plain_upper_half_threshold_.resize(coeff_bit_count);
        half_round_up_uint(plain_modulus_.pointer(), coeff_uint64_count, plain_upper_half_threshold_.pointer());

        // Calculate coeff_modulus - plain_modulus.
        plain_upper_half_increment_.resize(coeff_bit_count);
        sub_uint_uint(coeff_modulus_.pointer(), plain_modulus_.pointer(), coeff_uint64_count, plain_upper_half_increment_.pointer());

        // Calculate (plain_modulus + 1) / 2 * coeff_div_plain_modulus.
        upper_half_threshold_.resize(coeff_bit_count);
        multiply_truncate_uint_uint(plain_upper_half_threshold_.pointer(), coeff_div_plain_modulus_.pointer(), coeff_uint64_count, upper_half_threshold_.pointer());

        // Calculate upper_half_increment.
        upper_half_increment_.resize(coeff_bit_count);
        multiply_truncate_uint_uint(plain_modulus_.pointer(), coeff_div_plain_modulus_.pointer(), coeff_uint64_count, upper_half_increment_.pointer());
        sub_uint_uint(coeff_modulus_.pointer(), upper_half_increment_.pointer(), coeff_uint64_count, upper_half_increment_.pointer());

        // Widen coeff modulus.
        int product_coeff_bit_count = coeff_bit_count + coeff_bit_count + get_significant_bit_count(static_cast<uint64_t>(coeff_count));
        int plain_modulus_bit_count = plain_modulus_.significant_bit_count();
        int wide_bit_count = product_coeff_bit_count + plain_modulus_bit_count;
        int wide_uint64_count = divide_round_up(wide_bit_count, bits_per_uint64);
        wide_coeff_modulus_.resize(wide_bit_count);
        wide_coeff_modulus_ = coeff_modulus_;

        // Calculate wide_coeff_modulus_ / 2.
        wide_coeff_modulus_div_two_.resize(wide_bit_count);
        right_shift_uint(wide_coeff_modulus_.pointer(), 1, wide_uint64_count, wide_coeff_modulus_div_two_.pointer());

        // Initialize moduli.
        polymod_ = PolyModulus(poly_modulus_.pointer(), coeff_count, coeff_uint64_count);
        if (mode_ == TEST_MODE)
        {
            mod_ = Modulus(plain_modulus_.pointer(), coeff_uint64_count, pool_);
        }
        else
        {
            mod_ = Modulus(coeff_modulus_.pointer(), coeff_uint64_count, pool_);
        }
    }