eddsa

Documentation

Index

• Variables
• func PackSignY(sign bool, y *big.Int) [32]byte
• func PointCoordSign(c *big.Int) bool
• func SkToBigInt(k *PrivateKey) *big.Int
• func UnpackSignY(leBuf [32]byte) (bool, *big.Int)
• type Point
  • func NewPoint() *Point
  • func PointFromSignAndY(sign bool, y *big.Int) (*Point, error)
  • func (p *Point) Compress() [32]byte
  • func (p *Point) Decompress(leBuf [32]byte) (*Point, error)
  • func (p *Point) Mul(s *big.Int, q *Point) *Point
  • func (p *Point) Projective() *PointProjective
• type PointProjective
  • func NewPointProjective() *PointProjective
  • func (p *PointProjective) Add(q *PointProjective, o *PointProjective) *PointProjective
  • func (p *PointProjective) Affine() *Point
• type PrivKeyScalar
  • func NewPrivKeyScalar(s *big.Int) *PrivKeyScalar
  • func (s *PrivKeyScalar) BigInt() *big.Int
  • func (s *PrivKeyScalar) Public() *PublicKey
• type PrivateKey
  • func (k *PrivateKey) Public() *PublicKey
  • func (k *PrivateKey) Scalar() *PrivKeyScalar
  • func (k *PrivateKey) SignPoseidon(msg *big.Int) *Signature
• type PublicKey
  • func (pk *PublicKey) Point() *Point
  • func (pk *PublicKey) VerifyPoseidon(msg *big.Int, sig *Signature) bool
• type Signature
  • func (s *Signature) Compress() SignatureComp
  • func (s *Signature) Decompress(buf [64]byte) (*Signature, error)
• type SignatureComp

Variables

var A *big.Int

A is one of the babyjub constants.

var Aff *ff.Element

Aff is A value in *ff.Element representation

var C *big.Int

Cofactor.

var D *big.Int

D is one of the babyjub constants.

var Dff *ff.Element

Dff is D value in *ff.Element representation

var L *big.Int

L*B = 0, and (2^C)*L == #E

var Order *big.Int

Order of the babyjub curve.

var SubOrder *big.Int

SubOrder is the order of the subgroup of the babyjub curve that contains the points that we use.

Functions

func PackSignY

func PackSignY(sign bool, y *big.Int) [32]byte

PackSignY packs the given sign and the coordinate Y of a point into a 32 byte array. This method does not check that the values belong to a valid Point in the curve.

func PointCoordSign

func PointCoordSign(c *big.Int) bool

PointCoordSign returns the sign of the curve point coordinate. It returns false if the sign is positive and false if the sign is negative.

func SkToBigInt

func SkToBigInt(k *PrivateKey) *big.Int

SkToBigInt converts a private key into the *big.Int value following the EdDSA standard, and using blake-512 hash

func UnpackSignY

func UnpackSignY(leBuf [32]byte) (bool, *big.Int)

UnpackSignY returns the sign and coordinate Y from a given compressed point. This method does not check that the Point belongs to the BabyJubJub curve, thus does not return error in such case. This method is intended to obtain the sign and the Y coordinate without checking if the point belongs to the curve, if the objective is to uncompress a point, Decompress method should be used instead.

Types

type Point

type Point struct {
	X *big.Int
	Y *big.Int
}

Point represents a point of the babyjub curve.

var B8 *Point

B8 is a base point of the babyjub multiplied by 8 to make it a base point of the subgroup in the curve.

func NewPoint

func NewPoint() *Point

NewPoint creates a new Point.

func PointFromSignAndY

func PointFromSignAndY(sign bool, y *big.Int) (*Point, error)

PointFromSignAndY returns a Point from a Sign and the Y coordinate

func (*Point) Compress

func (p *Point) Compress() [32]byte

Compress the point into a 32 byte array that contains the y coordinate in little endian and the sign of the x coordinate.

func (*Point) Decompress

func (p *Point) Decompress(leBuf [32]byte) (*Point, error)

Decompress a compressed Point into p, and also returns the decompressed Point. Returns error if the compressed Point is invalid.

func (*Point) Mul

func (p *Point) Mul(s *big.Int, q *Point) *Point

Mul multiplies the Point q by the scalar s and stores the result in p, which is also returned.

func (*Point) Projective

func (p *Point) Projective() *PointProjective

Projective returns a PointProjective from the Point

type PointProjective

type PointProjective struct {
	X *ff.Element
	Y *ff.Element
	Z *ff.Element
}

PointProjective is the Point representation in projective coordinates

func NewPointProjective

func NewPointProjective() *PointProjective

NewPointProjective creates a new Point in projective coordinates.

func (*PointProjective) Add

func (p *PointProjective) Add(q *PointProjective, o *PointProjective) *PointProjective

Add computes the addition of two points in projective coordinates representation

func (*PointProjective) Affine

func (p *PointProjective) Affine() *Point

Affine returns the Point from the projective representation

type PrivKeyScalar

type PrivKeyScalar big.Int

PrivKeyScalar represents the scalar s output of a private key

func NewPrivKeyScalar

func NewPrivKeyScalar(s *big.Int) *PrivKeyScalar

NewPrivKeyScalar creates a new PrivKeyScalar from a big.Int

func (*PrivKeyScalar) BigInt

func (s *PrivKeyScalar) BigInt() *big.Int

BigInt returns the big.Int corresponding to a PrivKeyScalar.

func (*PrivKeyScalar) Public

func (s *PrivKeyScalar) Public() *PublicKey

Public returns the public key corresponding to the scalar value s of a private key.

type PrivateKey

type PrivateKey [32]byte

PrivateKey is an EdDSA private key, which is a 32byte buffer.

func (*PrivateKey) Public

func (k *PrivateKey) Public() *PublicKey

Public returns the public key corresponding to a private key.

func (*PrivateKey) Scalar

func (k *PrivateKey) Scalar() *PrivKeyScalar

Scalar converts a private key into the scalar value s following the EdDSA standard, and using blake-512 hash.

func (*PrivateKey) SignPoseidon

func (k *PrivateKey) SignPoseidon(msg *big.Int) *Signature

SignPoseidon signs a message encoded as a big.Int in Zq using blake-512 hash for buffer hashing and Poseidon for big.Int hashing.

type PublicKey

type PublicKey Point

PublicKey represents an EdDSA public key, which is a curve point.

func (*PublicKey) Point

func (pk *PublicKey) Point() *Point

Point returns the Point corresponding to a PublicKey.

func (*PublicKey) VerifyPoseidon

func (pk *PublicKey) VerifyPoseidon(msg *big.Int, sig *Signature) bool

VerifyPoseidon verifies the signature of a message encoded as a big.Int in Zq using blake-512 hash for buffer hashing and Poseidon for big.Int hashing.

type Signature

type Signature struct {
	R8 *Point
	S  *big.Int
}

Signature represents an EdDSA uncompressed signature.

func (*Signature) Compress

func (s *Signature) Compress() SignatureComp

Compress an EdDSA signature by concatenating the compression of the point R8 and the Little-Endian encoding of S.

func (*Signature) Decompress

func (s *Signature) Decompress(buf [64]byte) (*Signature, error)

Decompress a compressed signature into s, and also returns the decompressed signature. Returns error if the Point decompression fails.

type SignatureComp

type SignatureComp [64]byte

SignatureComp represents a compressed EdDSA signature.