Ejemplo n.º 1
0
    void KeyGenerator::generate()
    {
        // Handle test-mode case.
        if (mode_ == TEST_MODE)
        {
            public_key_.set_zero();
            public_key_[0] = 1;
            secret_key_.set_zero();
            secret_key_[0] = 1;
            for (int i = 0; i < evaluation_keys_.count(); ++i)
            {
                evaluation_keys_[i].set_zero();
                evaluation_keys_[i][0] = 1;
            }
            return;
        }

        // Extract encryption parameters.
        int coeff_count = poly_modulus_.coeff_count();
        int coeff_bit_count = poly_modulus_.coeff_bit_count();
        int coeff_uint64_count = divide_round_up(coeff_bit_count, bits_per_uint64);

        // Loop until find a valid secret key.
        uint64_t *secret_key = secret_key_.pointer();
        set_zero_poly(coeff_count, coeff_uint64_count, secret_key);
        Pointer secret_key_inv(allocate_poly(coeff_count, coeff_uint64_count, pool_));
        while (true)
        {
            // Create noise with random [-1, 1] coefficients.
            set_poly_coeffs_zero_one_negone(secret_key);

            // Calculate secret_key * plaintext_modulus + 1.
            multiply_poly_scalar_coeffmod(secret_key, coeff_count, plain_modulus_.pointer(), mod_, secret_key, pool_);

            uint64_t *constant_coeff = get_poly_coeff(secret_key, 0, coeff_uint64_count);
            increment_uint_mod(constant_coeff, coeff_modulus_.pointer(), coeff_uint64_count, constant_coeff);

            // Attempt to invert secret_key.
            if (try_invert_poly_coeffmod(secret_key, poly_modulus_.pointer(), coeff_count, mod_, secret_key_inv.get(), pool_))
            {
                // Secret_key is invertible, so is valid
                break;
            }
        }

        // Calculate plaintext_modulus * noise * secret_key_inv.
        Pointer noise(allocate_poly(coeff_count, coeff_uint64_count, pool_));
        set_poly_coeffs_zero_one_negone(noise.get());
        uint64_t *public_key = public_key_.pointer();
        multiply_poly_poly_polymod_coeffmod(noise.get(), secret_key_inv.get(), polymod_, mod_, noise.get(), pool_);
        multiply_poly_scalar_coeffmod(noise.get(), coeff_count, plain_modulus_.pointer(), mod_, public_key, pool_);

        // Create evaluation keys.
        Pointer evaluation_factor(allocate_uint(coeff_uint64_count, pool_));
        set_uint(1, coeff_uint64_count, evaluation_factor.get());
        for (int i = 0; i < evaluation_keys_.count(); ++i)
        {
            // Multiply secret_key by evaluation_factor (mod coeff modulus).
            uint64_t *evaluation_key = evaluation_keys_[i].pointer();
            multiply_poly_scalar_coeffmod(secret_key, coeff_count, evaluation_factor.get(), mod_, evaluation_key, pool_);

            // Multiply public_key*normal noise and add into evaluation_key.
            set_poly_coeffs_normal(noise.get());
            multiply_poly_poly_polymod_coeffmod(noise.get(), public_key, polymod_, mod_, noise.get(), pool_);
            add_poly_poly_coeffmod(noise.get(), evaluation_key, coeff_count, coeff_modulus_.pointer(), coeff_uint64_count, evaluation_key);

            // Add-in more normal noise to evaluation_key.
            set_poly_coeffs_normal(noise.get());
            add_poly_poly_coeffmod(noise.get(), evaluation_key, coeff_count, coeff_modulus_.pointer(), coeff_uint64_count, evaluation_key);

            // Left shift evaluation factor.
            left_shift_uint(evaluation_factor.get(), decomposition_bit_count_, coeff_uint64_count, evaluation_factor.get());
        }
    }
Ejemplo n.º 2
0
    void KeyGenerator::generate(const BigPoly &secret_key, uint64_t power)
    {
        // Validate arguments.
        if (secret_key.is_zero())
        {
            throw invalid_argument("secret_key cannot be zero");
        }
        if (power == 0)
        {
            throw invalid_argument("power cannot be zero");
        }

        // Handle test-mode case.
        if (mode_ == TEST_MODE)
        {
            public_key_.set_zero();
            public_key_[0] = 1;
            secret_key_.set_zero();
            secret_key_[0] = 1;
            for (int i = 0; i < evaluation_keys_.count(); ++i)
            {
                evaluation_keys_[i].set_zero();
                evaluation_keys_[i][0] = 1;
            }
            return;
        }

        // Extract encryption parameters.
        int coeff_count = poly_modulus_.coeff_count();
        int coeff_bit_count = poly_modulus_.coeff_bit_count();
        int coeff_uint64_count = divide_round_up(coeff_bit_count, bits_per_uint64);

        // Verify secret key looks valid.
        secret_key_ = secret_key;
        if (secret_key_.coeff_count() != coeff_count || secret_key_.coeff_bit_count() != coeff_bit_count)
        {
            throw invalid_argument("secret_key is not valid for encryption parameters");
        }
#ifdef _DEBUG
        if (secret_key_.significant_coeff_count() == coeff_count || !are_poly_coefficients_less_than(secret_key_, coeff_modulus_))
        {
            throw invalid_argument("secret_key is not valid for encryption parameters");
        }
#endif

        // Raise level of secret key.
        if (power > 1)
        {
            exponentiate_poly_polymod_coeffmod(secret_key_.pointer(), &power, 1, polymod_, mod_, secret_key_.pointer(), pool_);
        }

        // Attempt to invert secret_key.
        Pointer secret_key_inv(allocate_poly(coeff_count, coeff_uint64_count, pool_));
        if (!try_invert_poly_coeffmod(secret_key_.pointer(), poly_modulus_.pointer(), coeff_count, mod_, secret_key_inv.get(), pool_))
        {
            // Secret_key is not invertible, so not valid.
            throw invalid_argument("secret_key is not valid for encryption parameters");
        }

        // Calculate plaintext_modulus * noise * secret_key_inv.
        Pointer noise(allocate_poly(coeff_count, coeff_uint64_count, pool_));
        set_poly_coeffs_zero_one_negone(noise.get());
        uint64_t *public_key = public_key_.pointer();
        multiply_poly_poly_polymod_coeffmod(noise.get(), secret_key_inv.get(), polymod_, mod_, noise.get(), pool_);
        multiply_poly_scalar_coeffmod(noise.get(), coeff_count, plain_modulus_.pointer(), mod_, public_key, pool_);

        // Create evaluation keys.
        Pointer evaluation_factor(allocate_uint(coeff_uint64_count, pool_));
        set_uint(1, coeff_uint64_count, evaluation_factor.get());
        for (int i = 0; i < evaluation_keys_.count(); ++i)
        {
            // Multiply secret_key by evaluation_factor (mod coeff modulus).
            uint64_t *evaluation_key = evaluation_keys_[i].pointer();
            multiply_poly_scalar_coeffmod(secret_key_.pointer(), coeff_count, evaluation_factor.get(), mod_, evaluation_key, pool_);

            // Multiply public_key*normal noise and add into evaluation_key.
            set_poly_coeffs_normal(noise.get());
            multiply_poly_poly_polymod_coeffmod(noise.get(), public_key, polymod_, mod_, noise.get(), pool_);
            add_poly_poly_coeffmod(noise.get(), evaluation_key, coeff_count, coeff_modulus_.pointer(), coeff_uint64_count, evaluation_key);

            // Add-in more normal noise to evaluation_key.
            set_poly_coeffs_normal(noise.get());
            add_poly_poly_coeffmod(noise.get(), evaluation_key, coeff_count, coeff_modulus_.pointer(), coeff_uint64_count, evaluation_key);

            // Left shift evaluation factor.
            left_shift_uint(evaluation_factor.get(), decomposition_bit_count_, coeff_uint64_count, evaluation_factor.get());
        }
    }
Ejemplo n.º 3
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_);
        }
    }