int get_significant_coeff_count_poly(const uint64_t *poly, int coeff_count, int coeff_uint64_count)
{
#ifdef _DEBUG
if (poly == nullptr && coeff_count > 0 && coeff_uint64_count > 0)
{
throw invalid_argument("poly");
}
if (coeff_count < 0)
{
throw invalid_argument("coeff_count");
}
if (coeff_uint64_count < 0)
{
throw invalid_argument("coeff_uint64_count");
}
#endif
poly += coeff_count * coeff_uint64_count;
for (int i = coeff_count; i > 0; --i)
{
poly -= coeff_uint64_count;
if (!is_zero_uint(poly, coeff_uint64_count))
{
return i;
}
}
return 0;
}
Modulus::Modulus(const std::uint64_t *modulus, int uint64_count, MemoryPool &pool) :
modulus_(modulus), uint64_count_(uint64_count)
{
#ifdef SEAL_DEBUG
if (modulus == nullptr)
{
throw invalid_argument("modulus");
}
if (uint64_count <= 0)
{
throw invalid_argument("uint64_count");
}
if (is_zero_uint(modulus, uint64_count))
{
throw invalid_argument("modulus");
}
#endif
significant_bit_count_ = get_significant_bit_count_uint(modulus, uint64_count);
power_of_two_minus_one_ = get_power_of_two_minus_one_uint(modulus, uint64_count);
if (is_inverse_small(modulus, significant_bit_count_))
{
// Calculate inverse modulus (clipped to modulus_bits).
inverse_modulus_ = allocate_uint(uint64_count, pool);
negate_uint(modulus, uint64_count, inverse_modulus_.get());
filter_highbits_uint(inverse_modulus_.get(), uint64_count, significant_bit_count_ - 1);
inverse_significant_bit_count_ = get_significant_bit_count_uint(inverse_modulus_.get(), uint64_count);
}
}
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_);
}
void exponentiate_poly(const std::uint64_t *poly,
int poly_coeff_count, int poly_coeff_uint64_count,
const uint64_t *exponent, int exponent_uint64_count,
int result_coeff_count, int result_coeff_uint64_count,
std::uint64_t *result, MemoryPool &pool)
{
#ifdef SEAL_DEBUG
if (poly == nullptr)
{
throw invalid_argument("poly");
}
if (poly_coeff_count <= 0)
{
throw invalid_argument("poly_coeff_count");
}
if (poly_coeff_count <= 0)
{
throw invalid_argument("poly_coeff_uint64_count");
}
if (exponent == nullptr)
{
throw invalid_argument("exponent");
}
if (exponent_uint64_count <= 0)
{
throw invalid_argument("exponent_uint64_count");
}
if (result == nullptr)
{
throw invalid_argument("result");
}
if (result_coeff_count <= 0)
{
throw invalid_argument("result_coeff_count");
}
if (result_coeff_uint64_count <= 0)
{
throw invalid_argument("result_coeff_uint64_count");
}
#endif
// Fast cases
if (is_zero_uint(exponent, exponent_uint64_count))
{
set_zero_poly(result_coeff_count, result_coeff_uint64_count, result);
*result = 1;
return;
}
if (is_equal_uint(exponent, exponent_uint64_count, 1))
{
set_poly_poly(poly, poly_coeff_count, poly_coeff_uint64_count,
result_coeff_count, result_coeff_uint64_count, result);
return;
}
// Need to make a copy of exponent
Pointer exponent_copy(allocate_uint(exponent_uint64_count, pool));
set_uint_uint(exponent, exponent_uint64_count, exponent_copy.get());
// Perform binary exponentiation.
Pointer big_alloc(allocate_uint((static_cast<int64_t>(result_coeff_count) +
result_coeff_count + result_coeff_count) * result_coeff_uint64_count, pool));
uint64_t *powerptr = big_alloc.get();
uint64_t *productptr = get_poly_coeff(powerptr, result_coeff_count, result_coeff_uint64_count);
uint64_t *intermediateptr = get_poly_coeff(productptr, result_coeff_count, result_coeff_uint64_count);
set_poly_poly(poly, poly_coeff_count, poly_coeff_uint64_count, result_coeff_count, result_coeff_uint64_count, powerptr);
set_zero_poly(result_coeff_count, result_coeff_uint64_count, intermediateptr);
*intermediateptr = 1;
// Initially: power = operand and intermediate = 1, product is not initialized.
while (true)
{
if ((*exponent_copy.get() % 2) == 1)
{
multiply_poly_poly(powerptr, result_coeff_count, result_coeff_uint64_count, intermediateptr, result_coeff_count, result_coeff_uint64_count,
result_coeff_count, result_coeff_uint64_count, productptr, pool);
swap(productptr, intermediateptr);
}
right_shift_uint(exponent_copy.get(), 1, exponent_uint64_count, exponent_copy.get());
if (is_zero_uint(exponent_copy.get(), exponent_uint64_count))
{
break;
}
multiply_poly_poly(powerptr, result_coeff_count, result_coeff_uint64_count, powerptr, result_coeff_count, result_coeff_uint64_count,
result_coeff_count, result_coeff_uint64_count, productptr, pool);
swap(productptr, powerptr);
}
set_poly_poly(intermediateptr, result_coeff_count, result_coeff_uint64_count, result);
}
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_);
}
}
