seal_fhe 0.8.1

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license.

#pragma once

#include "seal/context.h"
#include "seal/dynarray.h"
#include "seal/encryptionparams.h"
#include "seal/memorymanager.h"
#include "seal/valcheck.h"
#include "seal/version.h"
#include "seal/util/common.h"
#include "seal/util/defines.h"
#include "seal/util/polycore.h"
#include <algorithm>
#include <functional>
#include <stdexcept>
#include <string>
#ifdef SEAL_USE_MSGSL
#include "gsl/span"
#endif

namespace seal
{
    /**
    Class to store a plaintext element. The data for the plaintext is a polynomial
    with coefficients modulo the plaintext modulus. The degree of the plaintext
    polynomial must be one less than the degree of the polynomial modulus. The
    backing array always allocates one 64-bit word per each coefficient of the
    polynomial.

    @par Memory Management
    The coefficient count of a plaintext refers to the number of word-size
    coefficients in the plaintext, whereas its capacity refers to the number of
    word-size coefficients that fit in the current memory allocation. In high-
    performance applications unnecessary re-allocations should be avoided by
    reserving enough memory for the plaintext to begin with either by providing
    the desired capacity to the constructor as an extra argument, or by calling
    the reserve function at any time.

    When the scheme is scheme_type::bfv each coefficient of a plaintext is a 64-bit
    word, but when the scheme is scheme_type::ckks the plaintext is by default
    stored in an NTT transformed form with respect to each of the primes in the
    coefficient modulus. Thus, the size of the allocation that is needed is the
    size of the coefficient modulus (number of primes) times the degree of the
    polynomial modulus. In addition, a valid CKKS plaintext also store the parms_id
    for the corresponding encryption parameters.

    @par Thread Safety
    In general, reading from plaintext is thread-safe as long as no other thread
    is concurrently mutating it. This is due to the underlying data structure
    storing the plaintext not being thread-safe.

    @see Ciphertext for the class that stores ciphertexts.
    */
    class Plaintext
    {
    public:
        using pt_coeff_type = std::uint64_t;

        /**
        Constructs an empty plaintext allocating no memory.

        @param[in] pool The MemoryPoolHandle pointing to a valid memory pool
        @throws std::invalid_argument if pool is uninitialized
        */
        Plaintext(MemoryPoolHandle pool = MemoryManager::GetPool()) : data_(std::move(pool))
        {}

        /**
        Constructs a plaintext representing a constant polynomial 0. The coefficient
        count of the polynomial is set to the given value. The capacity is set to
        the same value.

        @param[in] coeff_count The number of (zeroed) coefficients in the plaintext
        polynomial
        @param[in] pool The MemoryPoolHandle pointing to a valid memory pool
        @throws std::invalid_argument if coeff_count is negative
        @throws std::invalid_argument if pool is uninitialized
        */
        explicit Plaintext(std::size_t coeff_count, MemoryPoolHandle pool = MemoryManager::GetPool())
            : coeff_count_(coeff_count), data_(coeff_count_, std::move(pool))
        {}

        /**
        Constructs a plaintext representing a constant polynomial 0. The coefficient
        count of the polynomial and the capacity are set to the given values.

        @param[in] capacity The capacity
        @param[in] coeff_count The number of (zeroed) coefficients in the plaintext
        polynomial
        @param[in] pool The MemoryPoolHandle pointing to a valid memory pool
        @throws std::invalid_argument if capacity is less than coeff_count
        @throws std::invalid_argument if coeff_count is negative
        @throws std::invalid_argument if pool is uninitialized
        */
        explicit Plaintext(
            std::size_t capacity, std::size_t coeff_count, MemoryPoolHandle pool = MemoryManager::GetPool())
            : coeff_count_(coeff_count), data_(capacity, coeff_count_, std::move(pool))
        {}
#ifdef SEAL_USE_MSGSL
        /**
        Constructs a plaintext representing a polynomial with given coefficient
        values. The coefficient count of the polynomial is set to the number of
        coefficient values provided, and the capacity is set to the given value.

        @param[in] coeffs Desired values of the plaintext coefficients
        @param[in] capacity The capacity
        @param[in] pool The MemoryPoolHandle pointing to a valid memory pool
        @throws std::invalid_argument if capacity is less than the size of coeffs
        @throws std::invalid_argument if pool is uninitialized
        */
        explicit Plaintext(
            gsl::span<const pt_coeff_type> coeffs, std::size_t capacity,
            MemoryPoolHandle pool = MemoryManager::GetPool())
            : coeff_count_(coeffs.size()), data_(coeffs, capacity, std::move(pool))
        {}

        /**
        Constructs a plaintext representing a polynomial with given coefficient
        values. The coefficient count of the polynomial is set to the number of
        coefficient values provided, and the capacity is set to the same value.

        @param[in] coeffs Desired values of the plaintext coefficients
        @param[in] pool The MemoryPoolHandle pointing to a valid memory pool
        @throws std::invalid_argument if pool is uninitialized
        */
        explicit Plaintext(gsl::span<const pt_coeff_type> coeffs, MemoryPoolHandle pool = MemoryManager::GetPool())
            : coeff_count_(coeffs.size()), data_(coeffs, std::move(pool))
        {}
#endif
        /**
        Constructs a plaintext from a given hexadecimal string describing the
        plaintext polynomial.

        The string description of the polynomial must adhere to the format returned
        by to_string(),
        which is of the form "7FFx^3 + 1x^1 + 3" and summarized by the following
        rules:
        1. Terms are listed in order of strictly decreasing exponent
        2. Coefficient values are non-negative and in hexadecimal format (upper
        and lower case letters are both supported)
        3. Exponents are positive and in decimal format
        4. Zero coefficient terms (including the constant term) may be (but do
        not have to be) omitted
        5. Term with the exponent value of one must be exactly written as x^1
        6. Term with the exponent value of zero (the constant term) must be written
        as just a hexadecimal number without exponent
        7. Terms must be separated by exactly <space>+<space> and minus is not
        allowed
        8. Other than the +, no other terms should have whitespace

        @param[in] hex_poly The formatted polynomial string specifying the plaintext
        polynomial
        @param[in] pool The MemoryPoolHandle pointing to a valid memory pool
        @throws std::invalid_argument if hex_poly does not adhere to the expected
        format
        @throws std::invalid_argument if pool is uninitialized
        */
        Plaintext(const std::string &hex_poly, MemoryPoolHandle pool = MemoryManager::GetPool())
            : data_(std::move(pool))
        {
            operator=(hex_poly);
        }

        /**
        Creates a new plaintext by copying a given one.

        @param[in] copy The plaintext to copy from
        */
        Plaintext(const Plaintext &copy) = default;

        /**
        Creates a new plaintext by moving a given one.

        @param[in] source The plaintext to move from
        */
        Plaintext(Plaintext &&source) = default;

        /**
        Creates a new plaintext by copying a given one.

        @param[in] copy The plaintext to copy from
        @param[in] pool The MemoryPoolHandle pointing to a valid memory pool
        @throws std::invalid_argument if pool is uninitialized
        */
        Plaintext(const Plaintext &copy, MemoryPoolHandle pool) : Plaintext(std::move(pool))
        {
            *this = copy;
        }

        /**
        Allocates enough memory to accommodate the backing array of a plaintext
        with given capacity.

        @param[in] capacity The capacity
        @throws std::invalid_argument if capacity is negative
        @throws std::logic_error if the plaintext is NTT transformed
        */
        void reserve(std::size_t capacity)
        {
            if (is_ntt_form())
            {
                throw std::logic_error("cannot reserve for an NTT transformed Plaintext");
            }
            data_.reserve(capacity);
            coeff_count_ = data_.size();
        }

        /**
        Allocates enough memory to accommodate the backing array of the current
        plaintext and copies it over to the new location. This function is meant
        to reduce the memory use of the plaintext to smallest possible and can be
        particularly important after modulus switching.
        */
        inline void shrink_to_fit()
        {
            data_.shrink_to_fit();
        }

        /**
        Resets the plaintext. This function releases any memory allocated by the
        plaintext, returning it to the memory pool.
        */
        inline void release() noexcept
        {
            parms_id_ = parms_id_zero;
            coeff_count_ = 0;
            scale_ = 1.0;
            data_.release();
        }

        /**
        Resizes the plaintext to have a given coefficient count. The plaintext
        is automatically reallocated if the new coefficient count does not fit in
        the current capacity.

        @param[in] coeff_count The number of coefficients in the plaintext polynomial
        @throws std::invalid_argument if coeff_count is negative
        @throws std::logic_error if the plaintext is NTT transformed
        */
        inline void resize(std::size_t coeff_count)
        {
            if (is_ntt_form())
            {
                throw std::logic_error("cannot reserve for an NTT transformed Plaintext");
            }
            data_.resize(coeff_count);
            coeff_count_ = coeff_count;
        }

        /**
        Copies a given plaintext to the current one.

        @param[in] assign The plaintext to copy from
        */
        Plaintext &operator=(const Plaintext &assign) = default;

        /**
        Moves a given plaintext to the current one.

        @param[in] assign The plaintext to move from
        */
        Plaintext &operator=(Plaintext &&assign) = default;

        /**
        Sets the value of the current plaintext to the polynomial represented by
        the a given hexadecimal string.

        The string description of the polynomial must adhere to the format returned
        by to_string(), which is of the form "7FFx^3 + 1x^1 + 3" and summarized
        by the following rules:
        1. Terms are listed in order of strictly decreasing exponent
        2. Coefficient values are non-negative and in hexadecimal format (upper
        and lower case letters are both supported)
        3. Exponents are positive and in decimal format
        4. Zero coefficient terms (including the constant term) may be (but do
        not have to be) omitted
        5. Term with the exponent value of one must be exactly written as x^1
        6. Term with the exponent value of zero (the constant term) must be
        written as just a hexadecimal number without exponent
        7. Terms must be separated by exactly <space>+<space> and minus is not
        allowed
        8. Other than the +, no other terms should have whitespace

        @param[in] hex_poly The formatted polynomial string specifying the plaintext
        polynomial
        @throws std::invalid_argument if hex_poly does not adhere to the expected
        format
        @throws std::invalid_argument if the coefficients of hex_poly are too wide
        */
        Plaintext &operator=(const std::string &hex_poly);

        /**
        Sets the value of the current plaintext to a given constant polynomial and
        sets the parms_id to parms_id_zero, effectively marking the plaintext as
        not NTT transformed. The coefficient count is set to one.

        @param[in] const_coeff The constant coefficient
        */
        Plaintext &operator=(pt_coeff_type const_coeff)
        {
            data_.resize(1);
            data_[0] = const_coeff;
            coeff_count_ = 1;
            parms_id_ = parms_id_zero;
            return *this;
        }
#ifdef SEAL_USE_MSGSL
        /**
        Sets the coefficients of the current plaintext to given values and sets
        the parms_id to parms_id_zero, effectively marking the plaintext as not
        NTT transformed.

        @param[in] coeffs Desired values of the plaintext coefficients
        */
        Plaintext &operator=(gsl::span<const pt_coeff_type> coeffs)
        {
            data_ = coeffs;
            coeff_count_ = coeffs.size();
            parms_id_ = parms_id_zero;
            return *this;
        }
#endif
        /**
        Sets a given range of coefficients of a plaintext polynomial to zero; does
        nothing if length is zero.

        @param[in] start_coeff The index of the first coefficient to set to zero
        @param[in] length The number of coefficients to set to zero
        @throws std::out_of_range if start_coeff + length - 1 is not within [0, coeff_count)
        */
        inline void set_zero(std::size_t start_coeff, std::size_t length)
        {
            if (!length)
            {
                return;
            }
            if (start_coeff + length - 1 >= coeff_count_)
            {
                throw std::out_of_range(
                    "length must be non-negative and start_coeff + length - 1 must be within [0, coeff_count)");
            }
            std::fill_n(data_.begin() + start_coeff, length, pt_coeff_type(0));
        }

        /**
        Sets the plaintext polynomial coefficients to zero starting at a given index.

        @param[in] start_coeff The index of the first coefficient to set to zero
        @throws std::out_of_range if start_coeff is not within [0, coeff_count)
        */
        inline void set_zero(std::size_t start_coeff)
        {
            if (start_coeff >= coeff_count_)
            {
                throw std::out_of_range("start_coeff must be within [0, coeff_count)");
            }
            std::fill(data_.begin() + start_coeff, data_.end(), pt_coeff_type(0));
        }

        /**
        Sets the plaintext polynomial to zero.
        */
        inline void set_zero()
        {
            std::fill(data_.begin(), data_.end(), pt_coeff_type(0));
        }

        /**
        Returns a reference to the backing DynArray object.
        */
        SEAL_NODISCARD inline const auto &dyn_array() const noexcept
        {
            return data_;
        }

        /**
        Returns a pointer to the beginning of the plaintext polynomial.
        */
        SEAL_NODISCARD inline pt_coeff_type *data()
        {
            return data_.begin();
        }

        /**
        Returns a const pointer to the beginning of the plaintext polynomial.
        */
        SEAL_NODISCARD inline const pt_coeff_type *data() const
        {
            return data_.cbegin();
        }
#ifdef SEAL_USE_MSGSL
        /**
        Returns a span pointing to the beginning of the text polynomial.
        */
        SEAL_NODISCARD inline gsl::span<pt_coeff_type> data_span()
        {
            return gsl::span<pt_coeff_type>(data_.begin(), coeff_count_);
        }

        /**
        Returns a span pointing to the beginning of the text polynomial.
        */
        SEAL_NODISCARD inline gsl::span<const pt_coeff_type> data_span() const
        {
            return gsl::span<const pt_coeff_type>(data_.cbegin(), coeff_count_);
        }
#endif
        /**
        Returns a pointer to a given coefficient of the plaintext polynomial.

        @param[in] coeff_index The index of the coefficient in the plaintext polynomial
        @throws std::out_of_range if coeff_index is not within [0, coeff_count)
        */
        SEAL_NODISCARD inline pt_coeff_type *data(std::size_t coeff_index)
        {
            if (!coeff_count_)
            {
                return nullptr;
            }
            if (coeff_index >= coeff_count_)
            {
                throw std::out_of_range("coeff_index must be within [0, coeff_count)");
            }
            return data_.begin() + coeff_index;
        }

        /**
        Returns a const pointer to a given coefficient of the plaintext polynomial.

        @param[in] coeff_index The index of the coefficient in the plaintext polynomial
        */
        SEAL_NODISCARD inline const pt_coeff_type *data(std::size_t coeff_index) const
        {
            if (!coeff_count_)
            {
                return nullptr;
            }
            if (coeff_index >= coeff_count_)
            {
                throw std::out_of_range("coeff_index must be within [0, coeff_count)");
            }
            return data_.cbegin() + coeff_index;
        }

        /**
        Returns a const reference to a given coefficient of the plaintext polynomial.

        @param[in] coeff_index The index of the coefficient in the plaintext polynomial
        @throws std::out_of_range if coeff_index is not within [0, coeff_count)
        */
        SEAL_NODISCARD inline const pt_coeff_type &operator[](std::size_t coeff_index) const
        {
            return data_.at(coeff_index);
        }

        /**
        Returns a reference to a given coefficient of the plaintext polynomial.

        @param[in] coeff_index The index of the coefficient in the plaintext polynomial
        @throws std::out_of_range if coeff_index is not within [0, coeff_count)
        */
        SEAL_NODISCARD inline pt_coeff_type &operator[](std::size_t coeff_index)
        {
            return data_.at(coeff_index);
        }

        /**
        Returns whether or not the plaintext has the same semantic value as a given
        plaintext. Leading zero coefficients are ignored by the comparison.

        @param[in] compare The plaintext to compare against
        */
        SEAL_NODISCARD inline bool operator==(const Plaintext &compare) const
        {
            std::size_t sig_coeff_count = significant_coeff_count();
            std::size_t sig_coeff_count_compare = compare.significant_coeff_count();
            bool parms_id_compare = (is_ntt_form() && compare.is_ntt_form() && (parms_id_ == compare.parms_id_)) ||
                                    (!is_ntt_form() && !compare.is_ntt_form());
            return parms_id_compare && (sig_coeff_count == sig_coeff_count_compare) &&
                   std::equal(
                       data_.cbegin(), data_.cbegin() + sig_coeff_count, compare.data_.cbegin(),
                       compare.data_.cbegin() + sig_coeff_count) &&
                   std::all_of(data_.cbegin() + sig_coeff_count, data_.cend(), util::is_zero<pt_coeff_type>) &&
                   std::all_of(
                       compare.data_.cbegin() + sig_coeff_count, compare.data_.cend(), util::is_zero<pt_coeff_type>) &&
                   util::are_close(scale_, compare.scale_);
        }

        /**
        Returns whether or not the plaintext has a different semantic value than
        a given plaintext. Leading zero coefficients are ignored by the comparison.

        @param[in] compare The plaintext to compare against
        */
        SEAL_NODISCARD inline bool operator!=(const Plaintext &compare) const
        {
            return !operator==(compare);
        }

        /**
        Returns whether the current plaintext polynomial has all zero coefficients.
        */
        SEAL_NODISCARD inline bool is_zero() const
        {
            return !coeff_count_ || std::all_of(data_.cbegin(), data_.cend(), util::is_zero<pt_coeff_type>);
        }

        /**
        Returns the capacity of the current allocation.
        */
        SEAL_NODISCARD inline std::size_t capacity() const noexcept
        {
            return data_.capacity();
        }

        /**
        Returns the coefficient count of the current plaintext polynomial.
        */
        SEAL_NODISCARD inline std::size_t coeff_count() const noexcept
        {
            return coeff_count_;
        }

        /**
        Returns the significant coefficient count of the current plaintext polynomial.
        */
        SEAL_NODISCARD inline std::size_t significant_coeff_count() const
        {
            if (!coeff_count_)
            {
                return 0;
            }
            return util::get_significant_uint64_count_uint(data_.cbegin(), coeff_count_);
        }

        /**
        Returns the non-zero coefficient count of the current plaintext polynomial.
        */
        SEAL_NODISCARD inline std::size_t nonzero_coeff_count() const
        {
            if (!coeff_count_)
            {
                return 0;
            }
            return util::get_nonzero_uint64_count_uint(data_.cbegin(), coeff_count_);
        }

        /**
        Returns a human-readable string description of the plaintext polynomial.

        The returned string is of the form "7FFx^3 + 1x^1 + 3" with a format
        summarized by the following:
        1. Terms are listed in order of strictly decreasing exponent
        2. Coefficient values are non-negative and in hexadecimal format (hexadecimal
        letters are in upper-case)
        3. Exponents are positive and in decimal format
        4. Zero coefficient terms (including the constant term) are omitted unless
        the polynomial is exactly 0 (see rule 9)
        5. Term with the exponent value of one is written as x^1
        6. Term with the exponent value of zero (the constant term) is written as
        just a hexadecimal number without x or exponent
        7. Terms are separated exactly by <space>+<space>
        8. Other than the +, no other terms have whitespace
        9. If the polynomial is exactly 0, the string "0" is returned

        @throws std::invalid_argument if the plaintext is in NTT transformed form
        */
        SEAL_NODISCARD inline std::string to_string() const
        {
            if (is_ntt_form())
            {
                throw std::invalid_argument("cannot convert NTT transformed plaintext to string");
            }
            return util::poly_to_hex_string(data_.cbegin(), coeff_count_, 1);
        }

        /**
        Returns an upper bound on the size of the plaintext, as if it was written
        to an output stream.

        @param[in] compr_mode The compression mode
        @throws std::invalid_argument if the compression mode is not supported
        @throws std::logic_error if the size does not fit in the return type
        */
        SEAL_NODISCARD inline std::streamoff save_size(
            compr_mode_type compr_mode = Serialization::compr_mode_default) const
        {
            std::size_t members_size = Serialization::ComprSizeEstimate(
                util::add_safe(
                    sizeof(parms_id_),
                    sizeof(std::uint64_t), // coeff_count_
                    sizeof(scale_), util::safe_cast<std::size_t>(data_.save_size(compr_mode_type::none))),
                compr_mode);

            return util::safe_cast<std::streamoff>(util::add_safe(sizeof(Serialization::SEALHeader), members_size));
        }

        /**
        Saves the plaintext to an output stream. The output is in binary format
        and not human-readable. The output stream must have the "binary" flag set.

        @param[out] stream The stream to save the plaintext to
        @param[in] compr_mode The desired compression mode
        @throws std::invalid_argument if the compression mode is not supported
        @throws std::logic_error if the data to be saved is invalid, or if
        compression failed
        @throws std::runtime_error if I/O operations failed
        */
        inline std::streamoff save(
            std::ostream &stream, compr_mode_type compr_mode = Serialization::compr_mode_default) const
        {
            using namespace std::placeholders;
            return Serialization::Save(
                std::bind(&Plaintext::save_members, this, _1), save_size(compr_mode_type::none), stream, compr_mode,
                false);
        }

        /**
        Loads a plaintext from an input stream overwriting the current plaintext.
        No checking of the validity of the plaintext data against encryption
        parameters is performed. This function should not be used unless the
        plaintext comes from a fully trusted source.

        @param[in] context The SEALContext
        @param[in] stream The stream to load the plaintext from
        @throws std::invalid_argument if the encryption parameters are not valid
        @throws std::logic_error if the data cannot be loaded by this version of
        Microsoft SEAL, if the loaded data is invalid, or if decompression failed
        @throws std::runtime_error if I/O operations failed
        */
        inline std::streamoff unsafe_load(const SEALContext &context, std::istream &stream)
        {
            using namespace std::placeholders;
            return Serialization::Load(std::bind(&Plaintext::load_members, this, context, _1, _2), stream, false);
        }

        /**
        Loads a plaintext from an input stream overwriting the current plaintext.
        The loaded plaintext is verified to be valid for the given SEALContext.

        @param[in] context The SEALContext
        @param[in] stream The stream to load the plaintext from
        @throws std::invalid_argument if the encryption parameters are not valid
        @throws std::logic_error if the data cannot be loaded by this version of
        Microsoft SEAL, if the loaded data is invalid, or if decompression failed
        @throws std::runtime_error if I/O operations failed
        */
        inline std::streamoff load(const SEALContext &context, std::istream &stream)
        {
            Plaintext new_data(pool());
            auto in_size = new_data.unsafe_load(context, stream);
            if (!is_valid_for(new_data, context))
            {
                throw std::logic_error("Plaintext data is invalid");
            }
            std::swap(*this, new_data);
            return in_size;
        }

        /**
        Saves the plaintext to a given memory location. The output is in binary
        format and not human-readable.

        @param[out] out The memory location to write the plaintext to
        @param[in] size The number of bytes available in the given memory location
        @param[in] compr_mode The desired compression mode
        @throws std::invalid_argument if out is null or if size is too small to
        contain a SEALHeader, or if the compression mode is not supported
        @throws std::logic_error if the data to be saved is invalid, or if
        compression failed
        @throws std::runtime_error if I/O operations failed
        */
        inline std::streamoff save(
            seal_byte *out, std::size_t size, compr_mode_type compr_mode = Serialization::compr_mode_default) const
        {
            using namespace std::placeholders;
            return Serialization::Save(
                std::bind(&Plaintext::save_members, this, _1), save_size(compr_mode_type::none), out, size, compr_mode,
                false);
        }

        /**
        Loads a plaintext from a given memory location overwriting the current
        plaintext. No checking of the validity of the plaintext data against
        encryption parameters is performed. This function should not be used
        unless the plaintext comes from a fully trusted source.

        @param[in] context The SEALContext
        @param[in] in The memory location to load the plaintext from
        @param[in] size The number of bytes available in the given memory location
        @throws std::invalid_argument if the encryption parameters are not valid
        @throws std::invalid_argument if in is null or if size is too small to
        contain a SEALHeader
        @throws std::logic_error if the data cannot be loaded by this version of
        Microsoft SEAL, if the loaded data is invalid, or if decompression failed
        @throws std::runtime_error if I/O operations failed
        */
        inline std::streamoff unsafe_load(const SEALContext &context, const seal_byte *in, std::size_t size)
        {
            using namespace std::placeholders;
            return Serialization::Load(std::bind(&Plaintext::load_members, this, context, _1, _2), in, size, false);
        }

        /**
        Loads a plaintext from an input stream overwriting the current plaintext.
        The loaded plaintext is verified to be valid for the given SEALContext.

        @param[in] context The SEALContext
        @param[in] in The memory location to load the PublicKey from
        @param[in] size The number of bytes available in the given memory location
        @throws std::invalid_argument if the encryption parameters are not valid
        @throws std::invalid_argument if in is null or if size is too small to
        contain a SEALHeader
        @throws std::logic_error if the data cannot be loaded by this version of
        Microsoft SEAL, if the loaded data is invalid, or if decompression failed
        @throws std::runtime_error if I/O operations failed
        */
        inline std::streamoff load(const SEALContext &context, const seal_byte *in, std::size_t size)
        {
            Plaintext new_data(pool());
            auto in_size = new_data.unsafe_load(context, in, size);
            if (!is_valid_for(new_data, context))
            {
                throw std::logic_error("Plaintext data is invalid");
            }
            std::swap(*this, new_data);
            return in_size;
        }

        /**
        Returns whether the plaintext is in NTT form.
        */
        SEAL_NODISCARD inline bool is_ntt_form() const noexcept
        {
            return (parms_id_ != parms_id_zero);
        }

        /**
        Returns a reference to parms_id. The parms_id must remain zero unless the plaintext polynomial is in NTT form.

        @see EncryptionParameters for more information about parms_id.
        */
        SEAL_NODISCARD inline parms_id_type &parms_id() noexcept
        {
            return parms_id_;
        }

        /**
        Returns a const reference to parms_id. The parms_id must remain zero unless the plaintext polynomial is in NTT
        form.

        @see EncryptionParameters for more information about parms_id.
        */
        SEAL_NODISCARD inline const parms_id_type &parms_id() const noexcept
        {
            return parms_id_;
        }

        /**
        Returns a reference to the scale. This is only needed when using the CKKS encryption scheme. The user should
        have little or no reason to ever change the scale by hand.
        */
        SEAL_NODISCARD inline double &scale() noexcept
        {
            return scale_;
        }

        /**
        Returns a constant reference to the scale. This is only needed when using the CKKS encryption scheme.
        */
        SEAL_NODISCARD inline const double &scale() const noexcept
        {
            return scale_;
        }

        /**
        Returns the currently used MemoryPoolHandle.
        */
        SEAL_NODISCARD inline MemoryPoolHandle pool() const noexcept
        {
            return data_.pool();
        }

        /**
        Enables access to private members of seal::Plaintext for SEAL_C.
        */
        struct PlaintextPrivateHelper;

    private:
        void save_members(std::ostream &stream) const;

        void load_members(const SEALContext &context, std::istream &stream, SEALVersion version);

        parms_id_type parms_id_ = parms_id_zero;

        std::size_t coeff_count_ = 0;

        double scale_ = 1.0;

        DynArray<pt_coeff_type> data_;

        // SecretKey needs access to save_members/load_members
        friend class SecretKey;
    };
} // namespace seal