Class Field2n

• Defined in File field2n.h

Inheritance Relationships

Base Types

• public std::vector< std::complex< double > >

• public lbcrypto::Serializable (Class Serializable)

Class Documentation

class lbcrypto::Field2n : public std::vector<std::complex<double>>, public lbcrypto::Serializable

Inheritence diagram for lbcrypto::Field2n:

Collaboration diagram for lbcrypto::Field2n:

A class to represent field elements with power-of-2 dimension.

Public Functions

Field2n() noexcept = default

Default Constructor.

inline explicit Field2n(Format f)

inline Field2n(usint size, Format f = Format::EVALUATION, bool initializeElementToZero = false)

Constructor for field element.

Parameters

• size – element size

• f – format/representation of the element. Initially set to Format::EVALUATION representation.

• initializeElementToZero – flag for initializing values to zero. It is set to false by default.

explicit Field2n(const Poly &element)

Constructor from ring element.

Parameters

& – element ring element

explicit Field2n(const NativePoly &element)

Constructor from ring element.

Parameters

& – element ring element

explicit Field2n(const DCRTPoly &element)

Constructor from DCRTPoly ring element.

Parameters

& – element ring element

explicit Field2n(const Matrix<int64_t> &element)

Constructor from a ring element matrix.

Parameters

&element – ring element matrix

inline Format GetFormat() const

Method for getting the format/representation of the element.

Returns

format/representation of the field element

Field2n Inverse() const

Inverse operation for the field elements.

Returns

the inverse field element

Field2n Plus(const Field2n &rhs) const

Addition operation for field elements.

Parameters

&rhs – right hand side element for operation

Returns

result of the operation

Field2n Plus(double rhs) const

Scalar addition operation for field elements.

Parameters

&rhs – right hand side element for operation

Returns

result of the operation

Field2n Minus(const Field2n &rhs) const

Substraction operation for field elements.

Parameters

&rhs – right hand side element for operation

Returns

result of the operation

Field2n Times(const Field2n &rhs) const

Multiplication operation for field elements.

Parameters

&rhs – right hand side element for operation

Returns

result of the operation

Field2n ShiftRight()

Right shift operation for the field element.

Returns

the shifted field element

Field2n AutomorphismTransform(size_t i) const

Performs an automorphism transform operation and returns the result.

Parameters

&i – is the element to perform the automorphism transform with.

Returns

is the result of the automorphism transform.

Field2n Transpose() const

Transpose operation defined in section VI.B4 of https://eprint.iacr.org/2017/844.pdf.

Returns

the transpose of the element

Field2n ExtractOdd() const

Function for extracting odd factors of the field element.

Returns

the field element with odd parts of the initial element

Field2n ExtractEven() const

Function for extracting even factors of the field element.

Returns

the field element with even parts of the initial element

Field2n Permute() const

Permutation operation defined in Algorithm 4 of https://eprint.iacr.org/2017/844.pdf.

Returns

permuted new field element

Field2n InversePermute() const

Inverse operation for permutation operation defined in Algorithm 4 of https://eprint.iacr.org/2017/844.pdf.

Returns

non permuted version of the element

Field2n ScalarMult(double d)

Operation for scalar multiplication.

Parameters

d – scalar for multiplication

Returns

the field element with the scalar multiplication

void SwitchFormat()

Method for switching format of the field elements.

inline void SetFormat(Format f)

Sets the evaluation or coefficient representation of the field elements.

Parameters

&format – the enum value corresponding to coefficient or evaluation representation

inline size_t Size() const

Method for getting the size of the element.

Returns

the size of the element

inline std::complex<double> &operator[](size_t idx)

Indexing operator for field elements.

Parameters

idx – index of the element

Returns

element at the index

inline const std::complex<double> &operator[](size_t idx) const

Indexing operator for field elements.

Parameters

idx – index of the element

Returns

element at the index

inline Field2n &operator+=(const Field2n &element)

In-place addition operation for field elements.

Parameters

&element – right hand side element for operation

Returns

result of the operation

inline Field2n &operator-=(const Field2n &element)

In-place subtraction operation for field elements.

Parameters

&element – right hand side element for operation

Returns

result of the operation

inline Field2n operator-() const

Unary minus on a field element.

Returns

negation of the field element.

template<class Archive>
inline void save(Archive &ar, std::uint32_t const version) const

template<class Archive>
inline void load(Archive &ar, std::uint32_t const version)

inline virtual std::string SerializedObjectName() const override

Public Static Functions

static inline uint32_t SerializedVersion()

Friends

inline friend Field2n operator-(const Field2n &a, const Field2n &b)

Substraction operator for field elements.

Parameters

• &a – left hand side field element

• &b – right hand side field element

Returns

result of the substraction operation

inline friend Field2n operator+(const Field2n &a, const Field2n &b)

Addition operator for field elements.

Parameters

• &a – left hand side field element

• &b – right hand side field element

Returns

result of the addition operation

inline friend Field2n operator+(const Field2n &a, double scalar)

Scalar addition operator for field elements.

Parameters

• &a – left hand side field element

• &b – the scalar to be added

Returns

result of the addition operation

inline friend Field2n operator*(const Field2n &a, const Field2n &b)

Multiplication operator for field elements.

Parameters

• &a – left hand side field element

• &b – right hand side field element

Returns

result of the multiplication operation