void Evaluator::sub_plain_inplace()

in native/src/seal/evaluator.cpp [1434:1506]

• 63 lines of code
• 17 McCabe index (conditional complexity)

    void Evaluator::sub_plain_inplace(Ciphertext &encrypted, const Plaintext &plain) const
    {
        // Verify parameters.
        if (!is_metadata_valid_for(encrypted, context_) || !is_buffer_valid(encrypted))
        {
            throw invalid_argument("encrypted is not valid for encryption parameters");
        }
        if (!is_metadata_valid_for(plain, context_) || !is_buffer_valid(plain))
        {
            throw invalid_argument("plain is not valid for encryption parameters");
        }

        auto &context_data = *context_.get_context_data(encrypted.parms_id());
        auto &parms = context_data.parms();
        if (parms.scheme() == scheme_type::bfv && encrypted.is_ntt_form())
        {
            throw invalid_argument("BFV encrypted cannot be in NTT form");
        }
        if (parms.scheme() == scheme_type::ckks && !encrypted.is_ntt_form())
        {
            throw invalid_argument("CKKS encrypted must be in NTT form");
        }
        if (plain.is_ntt_form() != encrypted.is_ntt_form())
        {
            throw invalid_argument("NTT form mismatch");
        }
        if (encrypted.is_ntt_form() && (encrypted.parms_id() != plain.parms_id()))
        {
            throw invalid_argument("encrypted and plain parameter mismatch");
        }
        if (!are_same_scale(encrypted, plain))
        {
            throw invalid_argument("scale mismatch");
        }

        // Extract encryption parameters.
        auto &coeff_modulus = parms.coeff_modulus();
        size_t coeff_count = parms.poly_modulus_degree();
        size_t coeff_modulus_size = coeff_modulus.size();

        // Size check
        if (!product_fits_in(coeff_count, coeff_modulus_size))
        {
            throw logic_error("invalid parameters");
        }

        switch (parms.scheme())
        {
        case scheme_type::bfv:
        {
            multiply_sub_plain_with_scaling_variant(plain, context_data, *iter(encrypted));
            break;
        }

        case scheme_type::ckks:
        {
            RNSIter encrypted_iter(encrypted.data(), coeff_count);
            ConstRNSIter plain_iter(plain.data(), coeff_count);
            sub_poly_coeffmod(encrypted_iter, plain_iter, coeff_modulus_size, coeff_modulus, encrypted_iter);
            break;
        }

        default:
            throw invalid_argument("unsupported scheme");
        }
#ifdef SEAL_THROW_ON_TRANSPARENT_CIPHERTEXT
        // Transparent ciphertext output is not allowed.
        if (encrypted.is_transparent())
        {
            throw logic_error("result ciphertext is transparent");
        }
#endif
    }