HkeyGen::HkeyGen(const EncryptionParameters &parms, const BigPoly &secret_key) :
poly_modulus_(parms.poly_modulus()), coeff_modulus_(parms.coeff_modulus()), plain_modulus_(parms.plain_modulus()), secret_key_(secret_key), orig_plain_modulus_bit_count_(parms.plain_modulus().significant_bit_count())
{
// 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 (secret_key_.is_zero())
{
throw invalid_argument("secret_key cannot be zero");
}
// 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 (secret_key_.coeff_count() != coeff_count || secret_key_.coeff_bit_count() != coeff_bit_count ||
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");
}
// Set the secret_key_array to have size 1 (first power of secret)
secret_key_array_.resize(1, coeff_count, coeff_bit_count);
set_poly_poly(secret_key_.pointer(), coeff_count, coeff_uint64_count, secret_key_array_.pointer(0));
MemoryPool &pool = *MemoryPool::default_pool();
// 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 coeff_modulus / plain_modulus / 2.
coeff_div_plain_modulus_div_two_.resize(coeff_bit_count);
right_shift_uint(coeff_div_plain_modulus_.pointer(), 1, coeff_uint64_count, coeff_div_plain_modulus_div_two_.pointer());
// Calculate coeff_modulus / 2.
upper_half_threshold_.resize(coeff_bit_count);
half_round_up_uint(coeff_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());
// 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_);
}
}
