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secp256k1.go
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secp256k1.go
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// Copyright (c) 2015-2016 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package chainec
import (
"errors"
"fmt"
"io"
"math/big"
"github.com/hybridnetwork/hxd/dcrec/secp256k1"
)
type secp256k1DSA struct {
// Constants
getN func() *big.Int
getP func() *big.Int
// EC Math
add func(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)
isOnCurve func(x *big.Int, y *big.Int) bool
scalarMult func(x, y *big.Int, k []byte) (*big.Int, *big.Int)
scalarBaseMult func(k []byte) (*big.Int, *big.Int)
// Private keys
newPrivateKey func(d *big.Int) PrivateKey
privKeyFromBytes func(pk []byte) (PrivateKey, PublicKey)
privKeyFromScalar func(pk []byte) (PrivateKey, PublicKey)
privKeyBytesLen func() int
// Public keys
newPublicKey func(x *big.Int, y *big.Int) PublicKey
parsePubKey func(pubKeyStr []byte) (PublicKey, error)
pubKeyBytesLen func() int
pubKeyBytesLenUncompressed func() int
pubKeyBytesLenCompressed func() int
pubKeyBytesLenHybrid func() int
// Signatures
newSignature func(r *big.Int, s *big.Int) Signature
parseDERSignature func(sigStr []byte) (Signature, error)
parseSignature func(sigStr []byte) (Signature, error)
recoverCompact func(signature, hash []byte) (PublicKey, bool, error)
// ECDSA
generateKey func(rand io.Reader) ([]byte, *big.Int, *big.Int, error)
sign func(priv PrivateKey, hash []byte) (r, s *big.Int, err error)
verify func(pub PublicKey, hash []byte, r, s *big.Int) bool
// Symmetric cipher encryption
generateSharedSecret func(privkey []byte, x, y *big.Int) []byte
encrypt func(x, y *big.Int, in []byte) ([]byte, error)
decrypt func(privkey []byte, in []byte) ([]byte, error)
}
var (
secp256k1Curve = secp256k1.S256()
)
// Boilerplate exported functions to make the struct interact with the interface.
// Constants
func (sp secp256k1DSA) GetP() *big.Int {
return sp.getP()
}
func (sp secp256k1DSA) GetN() *big.Int {
return sp.getN()
}
// EC Math
func (sp secp256k1DSA) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int) {
return sp.add(x1, y1, x2, y2)
}
func (sp secp256k1DSA) IsOnCurve(x, y *big.Int) bool {
return sp.isOnCurve(x, y)
}
func (sp secp256k1DSA) ScalarMult(x, y *big.Int, k []byte) (*big.Int, *big.Int) {
return sp.scalarMult(x, y, k)
}
func (sp secp256k1DSA) ScalarBaseMult(k []byte) (*big.Int, *big.Int) {
return sp.scalarBaseMult(k)
}
// Private keys
func (sp secp256k1DSA) NewPrivateKey(d *big.Int) PrivateKey {
return sp.newPrivateKey(d)
}
func (sp secp256k1DSA) PrivKeyFromBytes(pk []byte) (PrivateKey, PublicKey) {
return sp.privKeyFromBytes(pk)
}
func (sp secp256k1DSA) PrivKeyFromScalar(pk []byte) (PrivateKey, PublicKey) {
return sp.privKeyFromScalar(pk)
}
func (sp secp256k1DSA) PrivKeyBytesLen() int {
return sp.privKeyBytesLen()
}
// Public keys
func (sp secp256k1DSA) NewPublicKey(x *big.Int, y *big.Int) PublicKey {
return sp.newPublicKey(x, y)
}
func (sp secp256k1DSA) ParsePubKey(pubKeyStr []byte) (PublicKey, error) {
return sp.parsePubKey(pubKeyStr)
}
func (sp secp256k1DSA) PubKeyBytesLen() int {
return sp.pubKeyBytesLen()
}
func (sp secp256k1DSA) PubKeyBytesLenUncompressed() int {
return sp.pubKeyBytesLenUncompressed()
}
func (sp secp256k1DSA) PubKeyBytesLenCompressed() int {
return sp.pubKeyBytesLenCompressed()
}
func (sp secp256k1DSA) PubKeyBytesLenHybrid() int {
return sp.pubKeyBytesLenCompressed()
}
// Signatures
func (sp secp256k1DSA) NewSignature(r, s *big.Int) Signature {
return sp.newSignature(r, s)
}
func (sp secp256k1DSA) ParseDERSignature(sigStr []byte) (Signature, error) {
return sp.parseDERSignature(sigStr)
}
func (sp secp256k1DSA) ParseSignature(sigStr []byte) (Signature, error) {
return sp.parseSignature(sigStr)
}
func (sp secp256k1DSA) RecoverCompact(signature, hash []byte) (PublicKey, bool,
error) {
return sp.recoverCompact(signature, hash)
}
// ECDSA
func (sp secp256k1DSA) GenerateKey(rand io.Reader) ([]byte, *big.Int, *big.Int,
error) {
return sp.generateKey(rand)
}
func (sp secp256k1DSA) Sign(priv PrivateKey, hash []byte) (r, s *big.Int,
err error) {
r, s, err = sp.sign(priv, hash)
return
}
func (sp secp256k1DSA) Verify(pub PublicKey, hash []byte, r, s *big.Int) bool {
return sp.verify(pub, hash, r, s)
}
// Symmetric cipher encryption
func (sp secp256k1DSA) GenerateSharedSecret(privkey []byte, x, y *big.Int) []byte {
return sp.generateSharedSecret(privkey, x, y)
}
func (sp secp256k1DSA) Encrypt(x, y *big.Int, in []byte) ([]byte,
error) {
return sp.encrypt(x, y, in)
}
func (sp secp256k1DSA) Decrypt(privkey []byte, in []byte) ([]byte,
error) {
return sp.decrypt(privkey, in)
}
// newSecp256k1DSA instatiates a function DSA subsystem over the secp256k1
// curve. A caveat for the functions below is that they're all routed through
// interfaces, and nil returns from the library itself for interfaces must
// ALWAYS be checked by checking the return value by attempted dereference
// (== nil).
func newSecp256k1DSA() DSA {
var secp DSA = &secp256k1DSA{
// Constants
getP: func() *big.Int {
return secp256k1Curve.P
},
getN: func() *big.Int {
return secp256k1Curve.N
},
// EC Math
add: func(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int) {
return secp256k1Curve.Add(x1, y1, x2, y2)
},
isOnCurve: func(x, y *big.Int) bool {
return secp256k1Curve.IsOnCurve(x, y)
},
scalarMult: func(x, y *big.Int, k []byte) (*big.Int, *big.Int) {
return secp256k1Curve.ScalarMult(x, y, k)
},
scalarBaseMult: func(k []byte) (*big.Int, *big.Int) {
return secp256k1Curve.ScalarBaseMult(k)
},
// Private keys
newPrivateKey: func(d *big.Int) PrivateKey {
if d == nil {
return nil
}
pk := secp256k1.NewPrivateKey(secp256k1Curve, d)
if pk != nil {
return PrivateKey(pk)
}
return nil
},
privKeyFromBytes: func(pk []byte) (PrivateKey, PublicKey) {
priv, pub := secp256k1.PrivKeyFromBytes(secp256k1Curve, pk)
if priv == nil {
return nil, nil
}
if pub == nil {
return nil, nil
}
tpriv := PrivateKey(priv)
tpub := PublicKey(pub)
return tpriv, tpub
},
privKeyFromScalar: func(pk []byte) (PrivateKey, PublicKey) {
priv, pub := secp256k1.PrivKeyFromScalar(secp256k1Curve, pk)
if priv == nil {
return nil, nil
}
if pub == nil {
return nil, nil
}
tpriv := PrivateKey(priv)
tpub := PublicKey(pub)
return tpriv, tpub
},
privKeyBytesLen: func() int {
return secp256k1.PrivKeyBytesLen
},
// Public keys
newPublicKey: func(x *big.Int, y *big.Int) PublicKey {
pk := secp256k1.NewPublicKey(secp256k1Curve, x, y)
tpk := PublicKey(pk)
return tpk
},
parsePubKey: func(pubKeyStr []byte) (PublicKey, error) {
pk, err := secp256k1.ParsePubKey(pubKeyStr, secp256k1Curve)
if err != nil {
return nil, err
}
tpk := PublicKey(pk)
return tpk, err
},
pubKeyBytesLen: func() int {
return secp256k1.PubKeyBytesLenCompressed
},
pubKeyBytesLenUncompressed: func() int {
return secp256k1.PubKeyBytesLenUncompressed
},
pubKeyBytesLenCompressed: func() int {
return secp256k1.PubKeyBytesLenCompressed
},
pubKeyBytesLenHybrid: func() int {
return secp256k1.PubKeyBytesLenHybrid
},
// Signatures
newSignature: func(r *big.Int, s *big.Int) Signature {
sig := secp256k1.NewSignature(r, s)
ts := Signature(sig)
return ts
},
parseDERSignature: func(sigStr []byte) (Signature, error) {
sig, err := secp256k1.ParseDERSignature(sigStr, secp256k1Curve)
if err != nil {
return nil, err
}
ts := Signature(sig)
return ts, err
},
parseSignature: func(sigStr []byte) (Signature, error) {
sig, err := secp256k1.ParseSignature(sigStr, secp256k1Curve)
if err != nil {
return nil, err
}
ts := Signature(sig)
return ts, err
},
recoverCompact: func(signature, hash []byte) (PublicKey, bool, error) {
pk, bl, err := secp256k1.RecoverCompact(secp256k1Curve, signature,
hash)
tpk := PublicKey(pk)
return tpk, bl, err
},
// ECDSA
generateKey: func(rand io.Reader) ([]byte, *big.Int, *big.Int, error) {
return secp256k1.GenerateKey(secp256k1Curve, rand)
},
sign: func(priv PrivateKey, hash []byte) (r, s *big.Int, err error) {
if priv.GetType() != ECTypeSecp256k1 {
return nil, nil, errors.New("wrong type")
}
spriv, ok := priv.(*secp256k1.PrivateKey)
if !ok {
return nil, nil, errors.New("wrong type")
}
sig, err := spriv.Sign(hash)
if sig != nil {
r = sig.GetR()
s = sig.GetS()
}
return
},
verify: func(pub PublicKey, hash []byte, r, s *big.Int) bool {
spub := secp256k1.NewPublicKey(secp256k1Curve, pub.GetX(), pub.GetY())
ssig := secp256k1.NewSignature(r, s)
return ssig.Verify(hash, spub)
},
// Symmetric cipher encryption
generateSharedSecret: func(privkey []byte, x, y *big.Int) []byte {
sprivkey, _ := secp256k1.PrivKeyFromBytes(secp256k1Curve, privkey)
if sprivkey == nil {
return nil
}
spubkey := secp256k1.NewPublicKey(secp256k1Curve, x, y)
return secp256k1.GenerateSharedSecret(sprivkey, spubkey)
},
encrypt: func(x, y *big.Int, in []byte) ([]byte, error) {
spubkey := secp256k1.NewPublicKey(secp256k1Curve, x, y)
return secp256k1.Encrypt(spubkey, in)
},
decrypt: func(privkey []byte, in []byte) ([]byte, error) {
sprivkey, _ := secp256k1.PrivKeyFromBytes(secp256k1Curve, privkey)
if sprivkey == nil {
return nil, fmt.Errorf("failure deserializing privkey")
}
return secp256k1.Decrypt(sprivkey, in)
},
}
return secp.(DSA)
}