1package core
  2
  3import (
  4	"crypto/ecdsa"
  5	"crypto/elliptic"
  6	"crypto/rand"
  7	"encoding/hex"
  8	"errors"
  9	"math/big"
 10)
 11
 12// Address is the type data for addresses
 13type Address [32]byte
 14
 15func (addr Address) String() string {
 16	return hex.EncodeToString(addr[:])
 17}
 18
 19func NewKey() (*ecdsa.PrivateKey, error) {
 20	curve := elliptic.P256()
 21
 22	privatekey := new(ecdsa.PrivateKey)
 23	privatekey, err := ecdsa.GenerateKey(curve, rand.Reader)
 24	if err != nil {
 25		return nil, err
 26	}
 27
 28	return privatekey, err
 29}
 30
 31func PackPubK(pubK *ecdsa.PublicKey) []byte {
 32	return elliptic.Marshal(pubK.Curve, pubK.X, pubK.Y)
 33}
 34func UnpackPubK(b []byte) *ecdsa.PublicKey {
 35	x, y := elliptic.Unmarshal(elliptic.P256(), b)
 36	return &ecdsa.PublicKey{
 37		Curve: elliptic.P256(),
 38		X:     x,
 39		Y:     y,
 40	}
 41}
 42
 43func AddressFromPrivK(privK *ecdsa.PrivateKey) Address {
 44	h := HashBytes(PackPubK(&privK.PublicKey))
 45	return Address(h)
 46}
 47
 48func (sig *Signature) Bytes() []byte {
 49	b := sig.R.Bytes()
 50	b = append(b, sig.S.Bytes()...)
 51	return b
 52}
 53
 54func SignatureFromBytes(b []byte) (*Signature, error) {
 55	if len(b) != 64 {
 56		return nil, errors.New("Invalid signature")
 57	}
 58	rBytes := b[:32]
 59	sBytes := b[32:]
 60
 61	r := new(big.Int).SetBytes(rBytes)
 62	s := new(big.Int).SetBytes(sBytes)
 63
 64	sig := &Signature{
 65		R: r,
 66		S: s,
 67	}
 68	return sig, nil
 69}
 70
 71type Signature struct {
 72	R *big.Int
 73	S *big.Int
 74}
 75
 76func Sign(privK *ecdsa.PrivateKey, m []byte) (*Signature, error) {
 77	r := big.NewInt(0)
 78	s := big.NewInt(0)
 79
 80	hashMsg := HashBytes(m)
 81
 82	r, s, err := ecdsa.Sign(rand.Reader, privK, hashMsg[:])
 83	if err != nil {
 84		return nil, err
 85	}
 86	sig := &Signature{
 87		R: r,
 88		S: s,
 89	}
 90
 91	return sig, nil
 92
 93}
 94
 95func VerifySignature(pubK *ecdsa.PublicKey, m []byte, sig Signature) bool {
 96	hashMsg := HashBytes(m)
 97
 98	verified := ecdsa.Verify(pubK, hashMsg[:], sig.R, sig.S)
 99	return verified
100}