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v0.3.0 Latest Latest Go to latest Published: Aug 13, 2021 License: MIT Imports: 8 Imported by: 0

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README ¶

Prime-order Elliptic Curve Groups

Package group exposes operations over prime-order elliptic curve groups and their scalars and elements, and implements the latest hash-to-curve specification to date (https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11).

The following table indexes supported groups with hash-to-curve capability and links each one to the underlying implementations:

ID	Name	Production ready	Implementation
1	Ristretto255	n/a	github.com/gtank/ristretto255
2	Decaf448	n/a	n/a
3	P-256	n/a	github.com/armfazh/h2c-go-ref
4	P-384	n/a	github.com/armfazh/h2c-go-ref
5	P-521	n/a	github.com/armfazh/h2c-go-ref
6	Curve25519	n/a	filippo.io/edwards25519
7	Edwards25519	n/a	filippo.io/edwards25519
8	Curve448	n/a	github.com/armfazh/h2c-go-ref
9	Edwards448	n/a	github.com/armfazh/h2c-go-ref
10	Secp256k1	n/a	github.com/armfazh/h2c-go-ref

Documentation ¶

Overview ¶

Package group exposes a prime-order elliptic curve groups with additional hash-to-curve operations.

It implements the latest hash-to-curve specification to date (https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11).

Package group exposes a prime-order elliptic curve groups with additional hash-to-curve operations.

Constants ¶

This section is empty.

Variables ¶

This section is empty.

Functions ¶

This section is empty.

Types ¶

type Group ¶

type Group byte

Group defines registered groups for use in the implementation.

const (
	// Ristretto255Sha512 identifies the Ristretto255 group with SHA2-512 hash-to-group hashing.
	Ristretto255Sha512 Group = 1 + iota

	// P256Sha256 identifies a group over P256 with SHA2-512 hash-to-group hashing.
	P256Sha256

	// P384Sha512 identifies a group over P384 with SHA2-512 hash-to-group hashing.
	P384Sha512

	// P521Sha512 identifies a group over P521 with SHA2-512 hash-to-group hashing.
	P521Sha512

	// Curve25519Sha512 identifies a group over Curve25519 with SHA2-512 hash-to-group hashing.
	Curve25519Sha512

	// Edwards25519Sha512 identifies a group over Edwards25519 with SHA2-512 hash-to-group hashing.
	Edwards25519Sha512

	// Curve448Sha512 identifies a group over Curve448 with SHA2-512 hash-to-group hashing.
	Curve448Sha512

	// Edwards448Sha512 identifies a group over Edwards448 with SHA2-512 hash-to-group hashing.
	Edwards448Sha512

	// Secp256k1Sha256 identifies a group over Secp256k1 with SHA2-512 hash-to-group hashing.
	Secp256k1Sha256
)

func (Group) Available ¶

func (i Group) Available() bool

Available reports whether the given Group is linked into the binary.

func (Group) Base ¶

func (i Group) Base() *Point

Base returns the group's base point a.k.a. canonical generator.

func (Group) ElementLength ¶

func (i Group) ElementLength() int

ElementLength returns the byte size of an encoded element.

func (Group) HashToGroup ¶

func (i Group) HashToGroup(input, dst []byte) *Point

HashToGroup allows arbitrary input to be safely mapped to the curve of the Group.

func (Group) HashToScalar ¶

func (i Group) HashToScalar(input, dst []byte) *Scalar

HashToScalar allows arbitrary input to be safely mapped to the field.

func (Group) Identity ¶

func (i Group) Identity() *Point

Identity returns the group's identity element.

func (Group) MakeDST ¶

func (i Group) MakeDST(app, version string) ([]byte, error)

MakeDST builds a domain separation tag in the form of <app>-V<version>-CS<id>-<hash-to-curve-ID>, or returns an error.

func (Group) MultBytes ¶

func (i Group) MultBytes(scalar, element []byte) (*Point, error)

MultBytes allows []byte encodings of a scalar and an element of the Group to be multiplied.

func (Group) NewElement ¶

func (i Group) NewElement() *Point

NewElement returns a new, empty, element.

func (Group) NewScalar ¶

func (i Group) NewScalar() *Scalar

NewScalar returns a new, empty, scalar.

func (Group) String ¶

func (i Group) String() string

String returns the hash-to-curve string identifier of the ciphersuite.

type Point ¶

type Point struct {
	internal.Point
}

Point represents a point on the curve of the prime-order group.

func (*Point) Add ¶

func (p *Point) Add(point *Point) *Point

Add returns the sum of the Points, and does not change the receiver.

func (*Point) Bytes ¶

func (p *Point) Bytes() []byte

Bytes returns the compressed byte encoding of the point.

func (*Point) Copy ¶

func (p *Point) Copy() *Point

Copy returns a copy of the point.

func (*Point) Decode ¶

func (p *Point) Decode(in []byte) (*Point, error)

Decode decodes the input an sets the current point to its value, and returns it.

func (*Point) InvertMult ¶

func (p *Point) InvertMult(scalar *Scalar) *Point

InvertMult returns the scalar multiplication of the receiver point with the inverse of the given scalar.

func (*Point) IsIdentity ¶

func (p *Point) IsIdentity() bool

IsIdentity returns whether the point is the Group's identity point.

func (*Point) Mult ¶

func (p *Point) Mult(scalar *Scalar) *Point

Mult returns the scalar multiplication of the receiver point with the given scalar.

func (*Point) Sub ¶

func (p *Point) Sub(point *Point) *Point

Sub returns the difference between the Points, and does not change the receiver.

type Scalar ¶

type Scalar struct {
	internal.Scalar
}

Scalar represents a scalar in the prime-order group.

func (*Scalar) Add ¶

func (s *Scalar) Add(scalar *Scalar) *Scalar

Add returns the sum of the scalars, and does not change the receiver.

func (*Scalar) Bytes ¶

func (s *Scalar) Bytes() []byte

Bytes returns the byte encoding of the element.

func (*Scalar) Copy ¶

func (s *Scalar) Copy() *Scalar

Copy returns a copy of the Scalar.

func (*Scalar) Decode ¶

func (s *Scalar) Decode(in []byte) (*Scalar, error)

Decode decodes the input an sets the current scalar to its value, and returns it.

func (*Scalar) Invert ¶

func (s *Scalar) Invert() *Scalar

Invert returns the scalar's modular inverse ( 1 / scalar ), and does not change the receiver.

func (*Scalar) Mult ¶

func (s *Scalar) Mult(scalar *Scalar) *Scalar

Mult returns the multiplication of the scalars, and does not change the receiver.

func (*Scalar) Random ¶

func (s *Scalar) Random() *Scalar

Random sets the current scalar to a new random scalar and returns it.

func (*Scalar) Sub ¶

func (s *Scalar) Sub(scalar *Scalar) *Scalar

Sub returns the difference between the scalars, and does not change the receiver.

Source Files ¶

View all Source files

Directories ¶

Path	Synopsis
curve25519 Package curve25519 implements a prime-order group over Curve25519 with hash-to-curve.	Package curve25519 implements a prime-order group over Curve25519 with hash-to-curve.
edwards25519 Package edwards25519 wraps filippo.io/edwards25519 and exposes a simple prime-order group API with hash-to-curve.	Package edwards25519 wraps filippo.io/edwards25519 and exposes a simple prime-order group API with hash-to-curve.
hash2curve Package hash2curve provides hash-to-curve compatible hashing over arbitrary input.	Package hash2curve provides hash-to-curve compatible hashing over arbitrary input.
internal Package internal defines simple and abstract APIs to group Elements and Scalars.	Package internal defines simple and abstract APIs to group Elements and Scalars.
other Package other wraps an hash-to-curve implementation and exposes functions for operations on points and scalars.	Package other wraps an hash-to-curve implementation and exposes functions for operations on points and scalars.
ristretto Package ristretto allows simple and abstracted operations in the Ristretto255 group Package ristretto wraps "github.com/gtank/ristretto255" and exposes a simple prime-order group API with hash-to-curve.	Package ristretto allows simple and abstracted operations in the Ristretto255 group Package ristretto wraps "github.com/gtank/ristretto255" and exposes a simple prime-order group API with hash-to-curve.

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