edwards25519

Documentation

Overview

Package edwards25519 provides an optimized Go implementation of a Twisted Edwards curve that is isomorphic to Curve25519. For details see: http://ed25519.cr.yp.to/.

This code is based on Adam Langley's Go port of the public domain, "ref10" implementation of the ed25519 signing scheme in C from SUPERCOP. It was generalized and extended to support full kyber.Group arithmetic by the DEDIS lab at Yale and EPFL.

Due to the field element and group arithmetic optimizations described in the Ed25519 paper, this implementation generally performs extremely well, typically comparable to native C implementations. The tradeoff is that this code is completely specialized to a single curve.

Index

• type Curve
  • func (c *Curve) NewKey(stream cipher.Stream) kyber.Scalar
  • func (c *Curve) NewKeyAndSeed(stream cipher.Stream) (kyber.Scalar, []byte, []byte)
  • func (c *Curve) NewKeyAndSeedWithInput(buffer []byte) (kyber.Scalar, []byte, []byte)
  • func (c *Curve) Point() kyber.Point
  • func (c *Curve) PointLen() int
  • func (c *Curve) Scalar() kyber.Scalar
  • func (c *Curve) ScalarLen() int
  • func (c *Curve) String() string
• type SuiteEd25519
  • func NewBlakeSHA256Ed25519() *SuiteEd25519
  • func NewBlakeSHA256Ed25519WithRand(r cipher.Stream) *SuiteEd25519
  • func (s *SuiteEd25519) Hash() hash.Hash
  • func (s *SuiteEd25519) New(t reflect.Type) interface{}
  • func (s *SuiteEd25519) RandomStream() cipher.Stream
  • func (s *SuiteEd25519) Read(r io.Reader, objs ...interface{}) error
  • func (s *SuiteEd25519) Write(w io.Writer, objs ...interface{}) error
  • func (s *SuiteEd25519) XOF(key []byte) kyber.XOF

Types

type Curve

type Curve struct {
}

Curve represents the Ed25519 group. There are no parameters and no initialization is required because it supports only this one specific curve.

func (*Curve) NewKey

func (c *Curve) NewKey(stream cipher.Stream) kyber.Scalar

NewKey returns a formatted Ed25519 key (avoiding subgroup attack by requiring it to be a multiple of 8). NewKey implements the kyber/util/key.Generator interface.

func (*Curve) NewKeyAndSeed

func (c *Curve) NewKeyAndSeed(stream cipher.Stream) (kyber.Scalar, []byte, []byte)

NewKeyAndSeed returns a formatted Ed25519 key (avoid subgroup attack by requiring it to be a multiple of 8). It also returns the seed and the input used to generate the key.

func (*Curve) NewKeyAndSeedWithInput

func (c *Curve) NewKeyAndSeedWithInput(buffer []byte) (kyber.Scalar, []byte, []byte)

NewKeyAndSeedWithInput returns a formatted Ed25519 key (avoid subgroup attack by requiring it to be a multiple of 8). It also returns the input and the digest used to generate the key.

func (*Curve) Point

func (c *Curve) Point() kyber.Point

Point creates a new Point on the Ed25519 curve.

func (*Curve) PointLen

func (c *Curve) PointLen() int

PointLen returns 32, the size in bytes of an encoded Point on the Ed25519 curve.

func (*Curve) Scalar

func (c *Curve) Scalar() kyber.Scalar

Scalar creates a new Scalar for the prime-order subgroup of the Ed25519 curve. The scalars in this package implement kyber.Scalar's SetBytes method, interpreting the bytes as a little-endian integer, in order to remain compatible with other Ed25519 implementations, and with the standard implementation of the EdDSA signature.

func (*Curve) ScalarLen

func (c *Curve) ScalarLen() int

ScalarLen returns 32, the size in bytes of an encoded Scalar for the Ed25519 curve.

func (*Curve) String

func (c *Curve) String() string

Return the name of the curve, "Ed25519".

type SuiteEd25519

type SuiteEd25519 struct {
	Curve
	// contains filtered or unexported fields
}

SuiteEd25519 implements some basic functionalities such as Group, HashFactory, and XOFFactory.

func NewBlakeSHA256Ed25519

func NewBlakeSHA256Ed25519() *SuiteEd25519

NewBlakeSHA256Ed25519 returns a cipher suite based on package github.com/drand/kyber/xof/blake2xb, SHA-256, and the Ed25519 curve. It produces cryptographically random numbers via package crypto/rand.

func NewBlakeSHA256Ed25519WithRand

func NewBlakeSHA256Ed25519WithRand(r cipher.Stream) *SuiteEd25519

NewBlakeSHA256Ed25519WithRand returns a cipher suite based on package github.com/drand/kyber/xof/blake2xb, SHA-256, and the Ed25519 curve. It produces cryptographically random numbers via the provided stream r.

func (*SuiteEd25519) Hash

func (s *SuiteEd25519) Hash() hash.Hash

Hash returns a newly instanciated sha256 hash function.

func (*SuiteEd25519) New

func (s *SuiteEd25519) New(t reflect.Type) interface{}

New implements the kyber.Encoding interface

func (*SuiteEd25519) RandomStream

func (s *SuiteEd25519) RandomStream() cipher.Stream

RandomStream returns a cipher.Stream that returns a key stream from crypto/rand.

func (*SuiteEd25519) Read

func (s *SuiteEd25519) Read(r io.Reader, objs ...interface{}) error

func (*SuiteEd25519) Write

func (s *SuiteEd25519) Write(w io.Writer, objs ...interface{}) error

func (*SuiteEd25519) XOF

func (s *SuiteEd25519) XOF(key []byte) kyber.XOF

XOF returns an XOF which is implemented via the Blake2b hash.