lbcrypto::BluesteinFFT< VecType > Class Template Reference

Bluestein Fast Fourier Transform implemetation. More...

#include <transfrm.h>

Static Public Member Functions
static VecType	ForwardTransform (const VecType &element, const IntType &root, const usint cycloOrder)
static VecType	ForwardTransform (const VecType &element, const IntType &root, const usint cycloOrder, const ModulusRoot< IntType > &nttModulusRoot)
static VecType	PadZeros (const VecType &a, const usint finalSize)
static VecType	Resize (const VecType &a, usint lo, usint hi)
static void	PreComputeDefaultNTTModulusRoot (usint cycloOrder, const IntType &modulus)
	Precomputes the modulus needed for NTT operation in forward Bluestein transform. More...
static void	PreComputeRootTableForNTT (usint cycloOrder, const ModulusRoot< IntType > &nttModulusRoot)
	Precomputes the root of unity table needed for NTT operation in forward Bluestein transform. More...
static void	PreComputePowers (usint cycloOrder, const ModulusRoot< IntType > &modulusRoot)
	precomputes the powers of root used in forward Bluestein transform. More...
static void	PreComputeRBTable (usint cycloOrder, const ModulusRootPair< IntType > &modulusRootPair)
	precomputes the NTT transform of the power of root of unity used in the Bluestein transform. More...
static void	Reset ()

Static Public Attributes
static std::map< ModulusRoot< IntType >, VecType >	m_rootOfUnityTableByModulusRoot
static std::map< ModulusRoot< IntType >, VecType >	m_rootOfUnityInverseTableByModulusRoot
static std::map< ModulusRoot< IntType >, VecType >	m_powersTableByModulusRoot
static std::map< ModulusRootPair< IntType >, VecType >	m_RBTableByModulusRootPair

Detailed Description

template<typename VecType>
class lbcrypto::BluesteinFFT< VecType >

Bluestein Fast Fourier Transform implemetation.

Member Function Documentation

ForwardTransform()

template<typename VecType >

VecType lbcrypto::BluesteinFFT< VecType >::ForwardTransform ( const VecType &  element, const IntType &  root, const usint  cycloOrder  )

static

Forward transform.

Parameters

element	is the element to perform the transform on.
rootOfUnityTable	the root of unity table.
cycloOrder	is the cyclotomic order.

Returns

is the output result of the transform.

PadZeros()

template<typename VecType >

VecType lbcrypto::BluesteinFFT< VecType >::PadZeros ( const VecType &  a, const usint  finalSize  )

static

Parameters

a	is the input vector to be padded with zeros.
finalSize	is the length of the output vector.

Returns

output vector padded with (finalSize - initial size)additional zeros.

PreComputeDefaultNTTModulusRoot()

template<typename VecType >

void lbcrypto::BluesteinFFT< VecType >::PreComputeDefaultNTTModulusRoot ( usint  cycloOrder, const IntType &  modulus  )

static

Precomputes the modulus needed for NTT operation in forward Bluestein transform.

Parameters

cycloOrder	is the cyclotomic order of the polynomial.
modulus	is the modulus of the polynomial.

PreComputePowers()

template<typename VecType >

void lbcrypto::BluesteinFFT< VecType >::PreComputePowers ( usint  cycloOrder, const ModulusRoot< IntType > &  modulusRoot  )

static

precomputes the powers of root used in forward Bluestein transform.

Parameters

cycloOrder	is the cyclotomic order of the polynomial ring.
modulus	is the modulus of the polynomial ring.
root	is the root of unity s.t. root^2m = 1.

PreComputeRBTable()

template<typename VecType >

void lbcrypto::BluesteinFFT< VecType >::PreComputeRBTable ( usint  cycloOrder, const ModulusRootPair< IntType > &  modulusRootPair  )

static

precomputes the NTT transform of the power of root of unity used in the Bluestein transform.

Parameters

cycloOrder	is the cyclotomic order of the polynomial ring.
modulus	is the modulus of the polynomial ring.
root	is the root of unity s.t. root^2m = 1.
bigMod	is the modulus required for the NTT transform.
bigRoot	is the root of unity required for the NTT transform.

PreComputeRootTableForNTT()

template<typename VecType >

void lbcrypto::BluesteinFFT< VecType >::PreComputeRootTableForNTT ( usint  cycloOrder, const ModulusRoot< IntType > &  nttModulusRoot  )

static

Precomputes the root of unity table needed for NTT operation in forward Bluestein transform.

Parameters

cycloOrder	is the cyclotomic order of the polynomial ring.
modulus	is the modulus of the polynomial.

Reset()

template<typename VecType >

void lbcrypto::BluesteinFFT< VecType >::Reset ( )

static

Reset cached values for the transform to empty.

Resize()

template<typename VecType >

VecType lbcrypto::BluesteinFFT< VecType >::Resize ( const VecType &  a, usint  lo, usint  hi  )

static

Parameters

a	is the input vector to be resized.
lo	is lower coefficient index.
hi	is higher coefficient index.

Returns

output vector s.t output vector = a[lo]...a[hi].

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The documentation for this class was generated from the following files:

• src/core/include/math/transfrm.h
• src/core/lib/math/transfrm.cpp