edwards

package
v0.0.0-...-5e9972d Latest Latest
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 Go to latest Published: Sep 8, 2019 License: GPL-3.0 Imports: 13 Imported by: 0

Documentation

Index

Constants

View Source 
const (
	PrivScalarSize  = 32
	PrivKeyBytesLen = 64
)

These constants define the lengths of serialized private keys.

View Source 
const (
	PubKeyBytesLen = 32
)

These constants define the lengths of serialized public keys.

View Source 
const SignatureSize = 64

SignatureSize is the size of an encoded ECDSA signature.

Variables

View Source 
var Sha512VersionStringRFC6979 = []byte("Edwards+SHA512  ")

Sha512VersionStringRFC6979 is the RFC6979 nonce version for a Schnorr signature over the Curve25519 curve using BLAKE256 as the hash function.

Functions

func GenerateKeyPair 

func GenerateKeyPair() (*PrivateKey, *PublicKey, error)

GenerateKeyPair is a wrapper for ecdsa.GenerateKey that returns a PrivateKey instead of the normal ecdsa.PrivateKey.

func GetRFC6979Nonce 

func GetRFC6979Nonce(prv *PrivateKey, hash []byte) []byte

GetRFC6979Nonce -- returns the deterministic nonce.

func NewKeyFromSeed 

func NewKeyFromSeed(seed []byte) (*PrivateKey, *PublicKey, error)

NewKeyFromSeed calculates a private key from a seed.

func NonceRFC6979 

func NonceRFC6979(privkey *big.Int, hash []byte, extra []byte, version []byte) *big.Int

NonceRFC6979 generates an ECDSA nonce (`k`) deterministically according to RFC 6979. It takes a 32-byte hash as an input and returns 32-byte nonce to be used in ECDSA algorithm.

func PartialSign 

func PartialSign(hash []byte, prv *PrivateKey, groupPubkey *PublicKey, prvNonce *PrivateKey, pubNonce *PublicKey) (*big.Int, *big.Int, error)

PartialSign -- returns the partial signature of this private key.

func PrivKeyFromBytes 

func PrivKeyFromBytes(pkBytes []byte) (*PrivateKey, *PublicKey)

PrivKeyFromBytes returns a private and public key for `curve' based on the private key passed as an argument as a byte slice.

func PrivKeyFromScalar 

func PrivKeyFromScalar(p []byte) (*PrivateKey, *PublicKey, error)

PrivKeyFromScalar returns a private and public key for `curve' based on the 32-byte private scalar passed as an argument as a byte slice (encoded big endian int).

func PrivKeyFromSecret 

func PrivKeyFromSecret(s []byte) (*PrivateKey, *PublicKey)

PrivKeyFromSecret returns a private and public key for `curve' based on the 32-byte private key secret passed as an argument as a byte slice.

func Sign 

func Sign(priv *PrivateKey, hash []byte) (r, s *big.Int, err error)

Sign is the generalized and exported version of Ed25519 signing, that handles both standard private secrets and non-standard scalars.

func SignFromScalar 

func SignFromScalar(priv *PrivateKey, nonce []byte, hash []byte) (r, s *big.Int, err error)

SignFromScalar signs a message 'hash' using the given private scalar priv. It uses RFC6979 to generate a deterministic nonce. Considered experimental. r = kG, where k is the RFC6979 nonce s = r + hash512(k || A || M) * a

func SignFromSecretNoReader 

func SignFromSecretNoReader(priv *PrivateKey, hash []byte) (r, s *big.Int, err error)

SignFromSecretNoReader signs a message 'hash' using the given private key priv. It doesn't actually user the random reader.

func SignThreshold 

func SignThreshold(priv *PrivateKey, groupPub *PublicKey, hash []byte, privNonce *PrivateKey,
	pubNonceSum *PublicKey) (r, s *big.Int, err error)

SignThreshold signs a message 'hash' using the given private scalar priv in a threshold group signature. It uses RFC6979 to generate a deterministic nonce. Considered experimental. As opposed to the threshold signing function for secp256k1, this function takes the entirety of the public nonce point (all points added) instead of the public nonce point with n-1 keys added. r = K_Sum s = r + hash512(k || A || M) * a

func Verify 

func Verify(pub *PublicKey, hash []byte, r, s *big.Int) bool

Verify verifies a message 'hash' using the given public keys and signature.

Types

type PrivateKey 

type PrivateKey struct {
	// contains filtered or unexported fields
}

PrivateKey wraps an ecdsa.PrivateKey as a convenience mainly for signing things with the private key without having to directly import the ecdsa package.

func (PrivateKey) GetD 

func (p PrivateKey) GetD() *big.Int

GetD satisfies the chainec PrivateKey interface.

func (*PrivateKey) PubKey 

func (p *PrivateKey) PubKey() *PublicKey

PubKey returns the PublicKey corresponding to this private key.

func (PrivateKey) Public 

func (p PrivateKey) Public() (*big.Int, *big.Int)

Public returns the PublicKey corresponding to this private key.

func (PrivateKey) Serialize 

func (p PrivateKey) Serialize() []byte

Serialize returns the private key as a 32 byte big endian number.

func (PrivateKey) SerializeSecret 

func (p PrivateKey) SerializeSecret() []byte

SerializeSecret returns the 32 byte secret along with its public key as 64 bytes.

func (PrivateKey) Sign 

func (p PrivateKey) Sign(hash []byte) (*Signature, error)

Sign is the generalized and exported version of Ed25519 signing, that handles both standard private secrets and non-standard scalars.

func (PrivateKey) ToECDSA 

func (p PrivateKey) ToECDSA() *ecdsa.PrivateKey

ToECDSA returns the private key as a *ecdsa.PrivateKey.

type PublicKey 

type PublicKey ecdsa.PublicKey

PublicKey is an ecdsa.PublicKey with an additional function to serialize.

func NewPublicKey 

func NewPublicKey(x *big.Int, y *big.Int) *PublicKey

NewPublicKey instantiates a new public key.

func ParsePubKey 

func ParsePubKey(pubKeyStr []byte) (key *PublicKey, err error)

ParsePubKey parses a public key for an edwards curve from a bytestring into a ecdsa.Publickey, verifying that it is valid.

func PubkeyAdd 

func PubkeyAdd(pks []*PublicKey) *PublicKey

PubkeyAdd -- returns the aggregate of the pubkeys.

func (PublicKey) GetX 

func (p PublicKey) GetX() *big.Int

GetX satisfies the chainec PublicKey interface.

func (PublicKey) GetY 

func (p PublicKey) GetY() *big.Int

GetY satisfies the chainec PublicKey interface.

func (PublicKey) Serialize 

func (p PublicKey) Serialize() []byte

Serialize serializes a public key in a 32-byte compressed little endian format.

func (PublicKey) ToECDSA 

func (p PublicKey) ToECDSA() *ecdsa.PublicKey

ToECDSA returns the public key as a *ecdsa.PublicKey.

type Signature 

type Signature struct {
	R *big.Int
	S *big.Int
}

Signature is a type representing an ecdsa signature.

func CombinePartialSigs 

func CombinePartialSigs(sigs []*Signature) (*Signature, error)

CombinePartialSigs -- returns the signature of aggragation.

func NewSignature 

func NewSignature(r, s *big.Int) *Signature

NewSignature instantiates a new signature given some R,S values.

func ParseSignature 

func ParseSignature(sigStr []byte) (*Signature, error)

ParseSignature parses a signature in BER format for the curve type `curve' into a Signature type, performing some basic sanity checks.

func (Signature) GetR 

func (sig Signature) GetR() *big.Int

GetR satisfies the chainec Signature interface.

func (Signature) GetS 

func (sig Signature) GetS() *big.Int

GetS satisfies the chainec Signature interface.

func (*Signature) IsEqual 

func (sig *Signature) IsEqual(otherSig *Signature) bool

IsEqual compares this Signature instance to the one passed, returning true if both Signatures are equivalent. A signature is equivalent to another, if they both have the same scalar value for R and S.

func (Signature) Serialize 

func (sig Signature) Serialize() []byte

Serialize returns the ECDSA signature in the more strict format.

The signatures are encoded as 

sig[0:32]  R, a point encoded as little endian
sig[32:64] S, scalar multiplication/addition results = (ab+c) mod l
  encoded also as little endian

type TwistedEdwardsCurve 

type TwistedEdwardsCurve struct {
	*elliptic.CurveParams
	H int // Cofactor of the curve

	A, D, I *big.Int // Edwards curve equation parameter constants
	// contains filtered or unexported fields
}

TwistedEdwardsCurve extended an elliptical curve set of parameters to satisfy the interface of the elliptic package.

func Edwards 

func Edwards() *TwistedEdwardsCurve

Edwards returns a Curve which implements Ed25519.

func (*TwistedEdwardsCurve) Add 

func (curve *TwistedEdwardsCurve) Add(x1, y1, x2, y2 *big.Int) (x, y *big.Int)

Add adds two points represented by pairs of big integers on the elliptical curve.

func (*TwistedEdwardsCurve) Double 

func (curve *TwistedEdwardsCurve) Double(x1, y1 *big.Int) (x, y *big.Int)

Double adds the same pair of big integer coordinates to itself on the elliptical curve.

func (*TwistedEdwardsCurve) IsOnCurve 

func (curve *TwistedEdwardsCurve) IsOnCurve(x *big.Int, y *big.Int) bool

IsOnCurve returns bool to say if the point (x,y) is on the curve by checking (y^2 - x^2 - 1 - dx^2y^2) % P == 0.

func (TwistedEdwardsCurve) Params 

func (curve TwistedEdwardsCurve) Params() *elliptic.CurveParams

Params returns the parameters for the curve.

func (*TwistedEdwardsCurve) ScalarBaseMult 

func (curve *TwistedEdwardsCurve) ScalarBaseMult(k []byte) (x, y *big.Int)

ScalarBaseMult returns k*G, where G is the base point of the group and k is an integer in big-endian form. TODO Optimize this with field elements

func (*TwistedEdwardsCurve) ScalarMult 

func (curve *TwistedEdwardsCurve) ScalarMult(x1, y1 *big.Int, k []byte) (x, y *big.Int)

ScalarMult returns k*(Bx,By) where k is a number in big-endian form. This uses the repeated doubling method, which is variable time. TODO use a constant time method to prevent side channel attacks.

Source Files

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