lattigo/bfv/plaintext.go

package bfv

import (
	"github.com/ldsec/lattigo/v2/ring"
)

// Plaintext is a Element with only one Poly. It represents a Plaintext element in R_q that is the
// result of scaling the corresponding element of R_t up by Q/t. This is a generic all-purpose type
// of plaintext: it will work with for all operations. It is however less compact than PlaintextRingT
// and will result in less efficient Ciphert-Plaintext multiplication than PlaintextMul. See bfv/encoder.go
// for more information on plaintext types.
type Plaintext struct {
	*Element
	value *ring.Poly
}

// PlaintextRingT represents a plaintext element in R_t.
// This is the most compact representation of a plaintext, but performing operations have the extra-cost of performing
// the scaling up by Q/t. See bfv/encoder.go for more information on plaintext types.
type PlaintextRingT Plaintext

// PlaintextMul represents a plaintext element in R_q, in NTT and Montgomerry form, but without scale up by Q/t.
// A PlaintextMul is a special-purpose plaintext for efficient Ciphertext-Plaintext multiplication. However,
// other operations on plaintexts are not supported. See bfv/encoder.go for more information on plaintext types.
type PlaintextMul Plaintext

// NewPlaintext creates and allocates a new plaintext in RingQ (multiple moduli of Q).
// The plaintext will be in RingQ and scaled by Q/t.
// Slower encoding and larger plaintext size
func NewPlaintext(params *Parameters) *Plaintext {
	plaintext := &Plaintext{newPlaintextElement(params), nil}
	plaintext.value = plaintext.Element.value[0]
	return plaintext
}

// NewPlaintextRingT creates and allocates a new plaintext in RingT (single modulus T).
// The plaintext will be in RingT.
func NewPlaintextRingT(params *Parameters) *PlaintextRingT {

	plaintext := &PlaintextRingT{newPlaintextRingTElement(params), nil}
	plaintext.value = plaintext.Element.value[0]
	return plaintext
}

// NewPlaintextMul creates and allocates a new plaintext optimized for ciphertext x plaintext multiplication.
// The plaintext will be in the NTT and Montgomery domain of RingQ and not scaled by Q/t.
func NewPlaintextMul(params *Parameters) *PlaintextMul {
	plaintext := &PlaintextMul{newPlaintextMulElement(params), nil}
	plaintext.value = plaintext.Element.value[0]
	return plaintext
}