chainec

Documentation

Overview

Package chainec provides wrapper functions to abstract the ec functions.

Overview

This package provides thin wrappers around the ec or crypto function used to make it easier to go from btcec (btcd) to ed25519 (decred) for example without changing the main body of the code.

Index

• Constants
• Variables
• type DSA
• type PrivateKey
• type PublicKey
• type Signature

Constants

const (
	ECTypeSecp256k1  int = iota // 0
	ECTypeEdwards               // 1
	ECTypeSecSchnorr            // 2
)

-------------------------------------------------------------------------------- Accessible DSA suites for export.

Variables

var Edwards = newEdwardsDSA()

Edwards is the Ed25519 ECDSA signature system.

var SecSchnorr = newSecSchnorrDSA()

SecSchnorr is a Schnorr signature scheme about the secp256k1 curve implemented in libsecp256k1.

var Secp256k1 = newSecp256k1DSA()

Secp256k1 is the secp256k1 curve and ECDSA system used in Bitcoin.

Types

type DSA

type DSA interface {
	// ----------------------------------------------------------------------------
	// Constants
	//
	// GetP gets the prime modulus of the curve.
	GetP() *big.Int

	// GetN gets the prime order of the curve.
	GetN() *big.Int

	// ----------------------------------------------------------------------------
	// EC Math
	//
	// Add adds two points on the curve.
	Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)

	// IsOnCurve checks if a given point is on the curve.
	IsOnCurve(x *big.Int, y *big.Int) bool

	// ScalarMult gives the product of scalar multiplication of scalar k
	// by point (x,y) on the curve.
	ScalarMult(x, y *big.Int, k []byte) (*big.Int, *big.Int)

	// ScalarBaseMult gives the product of scalar multiplication of
	// scalar k by the base point (generator) of the curve.
	ScalarBaseMult(k []byte) (*big.Int, *big.Int)

	// ----------------------------------------------------------------------------
	// Private keys
	//
	// NewPrivateKey instantiates a new private key for the given
	// curve.
	NewPrivateKey(*big.Int) PrivateKey

	// PrivKeyFromBytes calculates the public key from serialized bytes,
	// and returns both it and the private key.
	PrivKeyFromBytes(pk []byte) (PrivateKey, PublicKey)

	// PrivKeyFromScalar calculates the public key from serialized scalar
	// bytes, and returns both it and the private key. Useful for curves
	// like Ed25519, where serialized private keys are different from
	// serialized private scalars.
	PrivKeyFromScalar(pk []byte) (PrivateKey, PublicKey)

	// PrivKeyBytesLen returns the length of a serialized private key.
	PrivKeyBytesLen() int

	// ----------------------------------------------------------------------------
	// Public keys
	//
	// NewPublicKey instantiates a new public key (point) for the
	// given curve.
	NewPublicKey(x *big.Int, y *big.Int) PublicKey

	// ParsePubKey parses a serialized public key for the given
	// curve and returns a public key.
	ParsePubKey(pubKeyStr []byte) (PublicKey, error)

	// PubKeyBytesLen returns the length of the default serialization
	// method for a public key.
	PubKeyBytesLen() int

	// PubKeyBytesLenUncompressed returns the length of the uncompressed
	// serialization method for a public key.
	PubKeyBytesLenUncompressed() int

	// PubKeyBytesLenCompressed returns the length of the compressed
	// serialization method for a public key.
	PubKeyBytesLenCompressed() int

	// ----------------------------------------------------------------------------
	// Signatures
	//
	// NewSignature instantiates a new signature for the given ECDSA
	// method.
	NewSignature(r *big.Int, s *big.Int) Signature

	// ParseDERSignature parses a DER encoded signature for the given
	// ECDSA method. If the method doesn't support DER signatures, it
	// just parses with the default method.
	ParseDERSignature(sigStr []byte) (Signature, error)

	// ParseSignature a default encoded signature for the given ECDSA
	// method.
	ParseSignature(sigStr []byte) (Signature, error)

	// RecoverCompact recovers a public key from an encoded signature
	// and message, then verifies the signature against the public
	// key.
	RecoverCompact(signature, hash []byte) (PublicKey, bool, error)

	// ----------------------------------------------------------------------------
	// ECDSA
	//
	// GenerateKey generates a new private and public keypair from the
	// given reader.
	GenerateKey(rand io.Reader) ([]byte, *big.Int, *big.Int, error)

	// Sign produces an ECDSA signature in the form of (R,S) using a
	// private key and a message.
	Sign(priv PrivateKey, hash []byte) (r, s *big.Int, err error)

	// Verify verifies an ECDSA signature against a given message and
	// public key.
	Verify(pub PublicKey, hash []byte, r, s *big.Int) bool

	// ----------------------------------------------------------------------------
	// Symmetric cipher encryption
	//
	// GenerateSharedSecret generates a shared secret using a private scalar
	// and a public key using ECDH.
	GenerateSharedSecret(privkey []byte, x, y *big.Int) []byte

	// Encrypt encrypts data to a recipient public key.
	Encrypt(x, y *big.Int, in []byte) ([]byte, error)

	// Decrypt decrypts data encoded to the public key that originates
	// from the passed private scalar.
	Decrypt(privkey []byte, in []byte) ([]byte, error)
}

DSA is an encapsulating interface for all the functions of a digital signature algorithm.

type PrivateKey

type PrivateKey interface {
	// Serialize serializes the 32-byte private key scalar to a
	// byte slice.
	Serialize() []byte

	// SerializeSecret serializes the secret to the default serialization
	// format. Used for Ed25519.
	SerializeSecret() []byte

	// Public returns the (X,Y) coordinates of the point produced
	// by scalar multiplication of the scalar by the base point,
	// AKA the public key.
	Public() (*big.Int, *big.Int)

	// GetD returns the value of the private scalar.
	GetD() *big.Int

	// GetType returns the ECDSA type of this key.
	GetType() int
}

PrivateKey is an interface representing a private key and its associated functions.

type PublicKey

type PublicKey interface {
	// Serialize is the default serialization method.
	Serialize() []byte

	// SerializeUncompressed serializes to the uncompressed format (if
	// available).
	SerializeUncompressed() []byte

	// SerializeCompressed serializes to the compressed format (if
	// available).
	SerializeCompressed() []byte

	// ToECDSA converts the public key to an ECDSA public key.
	ToECDSA() *ecdsa.PublicKey

	// GetCurve returns the current curve as an interface.
	GetCurve() interface{}

	// GetX returns the point's X value.
	GetX() *big.Int

	// GetY returns the point's Y value.
	GetY() *big.Int

	// GetType returns the ECDSA type of this key.
	GetType() int
}

PublicKey is an interface representing a public key and its associated functions.

type Signature

type Signature interface {
	// Serialize serializes the signature to the default serialization
	// format.
	Serialize() []byte

	// GetR gets the R value of the signature.
	GetR() *big.Int

	// GetS gets the S value of the signature.
	GetS() *big.Int

	// GetType returns the ECDSA type of this key.
	GetType() int
}

Signature is an interface representing a signature and its associated functions.