Key signature and wallet address get functions added to Public key (#144)

* small fixes

* gofmt

* fix in raw tx build

* fixes after review

* balance getter interface

* moved address and signature calculation to public key

* errors handling

* PublicKey() returns PublicKey instead of bytes slice

* fixes after review

* fixes after review

pkg/crypto/public_key.go

@@ -2,12 +2,14 @@ package crypto
 
 import (
 	"bytes"
+	"crypto/sha256"
 	"encoding/binary"
 	"encoding/hex"
 	"io"
 	"math/big"
 
 	"github.com/pkg/errors"
+	"golang.org/x/crypto/ripemd160"
 )
 
 // PublicKeys is a list of public keys.
@@ -43,7 +45,7 @@ func NewPublicKeyFromString(s string) (*PublicKey, error) {
 		return nil, err
 	}
 
-	pubKey := &PublicKey{}
+	pubKey := new(PublicKey)
 	if err := pubKey.DecodeBinary(bytes.NewReader(b)); err != nil {
 		return nil, err
 	}
@@ -140,3 +142,45 @@ func (p *PublicKey) DecodeBinary(r io.Reader) error {
 func (p *PublicKey) EncodeBinary(w io.Writer) error {
 	return binary.Write(w, binary.LittleEndian, p.Bytes())
 }
+
+func (p *PublicKey) Signature() ([]byte, error) {
+	b := p.Bytes()
+	b = append([]byte{0x21}, b...)
+	b = append(b, 0xAC)
+
+	sha := sha256.New()
+	sha.Write(b)
+	hash := sha.Sum(nil)
+
+	ripemd := ripemd160.New()
+	ripemd.Reset()
+	ripemd.Write(hash)
+	hash = ripemd.Sum(nil)
+
+	return hash, nil
+}
+
+func (p *PublicKey) Address() (string, error) {
+	var (
+		err error
+		b []byte
+	)
+	if b, err = p.Signature(); err != nil {
+		return "", err
+	}
+
+	b = append([]byte{0x17}, b...)
+
+	sha := sha256.New()
+	sha.Write(b)
+	hash := sha.Sum(nil)
+
+	sha.Reset()
+	sha.Write(hash)
+	hash = sha.Sum(nil)
+
+	b = append(b, hash[0:4]...)
+
+	address := Base58Encode(b)
+	return address, nil
+}

pkg/wallet/account.go

@@ -103,7 +103,7 @@ func newAccountFromPrivateKey(p *PrivateKey) (*Account, error) {
 	}
 
 	a := &Account{
-		publicKey:  pubKey,
+		publicKey:  pubKey.Bytes(),
 		privateKey: p,
 		Address:    pubAddr,
 		wif:        wif,

pkg/wallet/private_key.go

@@ -15,7 +15,6 @@ import (
 
 	"github.com/CityOfZion/neo-go/pkg/crypto"
 	"github.com/anthdm/rfc6979"
-	"golang.org/x/crypto/ripemd160"
 )
 
 // PrivateKey represents a NEO private key.
@@ -68,8 +67,10 @@ func NewPrivateKeyFromRawBytes(b []byte) (*PrivateKey, error) {
 }
 
 // PublicKey derives the public key from the private key.
-func (p *PrivateKey) PublicKey() ([]byte, error) {
+func (p *PrivateKey) PublicKey() (*crypto.PublicKey, error) {
 	var (
+		err error
+		pk crypto.PublicKey
 		c = crypto.NewEllipticCurve()
 		q = new(big.Int).SetBytes(p.b)
 	)
@@ -94,7 +95,10 @@ func (p *PrivateKey) PublicKey() ([]byte, error) {
 	}
 	b := append(prefix, padded...)
 
-	return b, nil
+	if err = pk.DecodeBytes(b); err != nil {
+		return nil, err
+	}
+	return &pk, nil
 }
 
 // NewPrivateKeyFromWIF returns a NEO PrivateKey from the given
@@ -117,48 +121,20 @@ func (p *PrivateKey) WIF() (string, error) {
 // Address derives the public NEO address that is coupled with the private key, and
 // returns it as a string.
 func (p *PrivateKey) Address() (string, error) {
-	b, err := p.Signature()
+	pk, err := p.PublicKey()
 	if err != nil {
 		return "", err
 	}
-
-	b = append([]byte{0x17}, b...)
-
-	sha := sha256.New()
-	sha.Write(b)
-	hash := sha.Sum(nil)
-
-	sha.Reset()
-	sha.Write(hash)
-	hash = sha.Sum(nil)
-
-	b = append(b, hash[0:4]...)
-
-	address := crypto.Base58Encode(b)
-
-	return address, nil
+	return pk.Address()
 }
 
 // Signature creates the signature using the private key.
 func (p *PrivateKey) Signature() ([]byte, error) {
-	b, err := p.PublicKey()
+	pk, err := p.PublicKey()
 	if err != nil {
 		return nil, err
 	}
-
-	b = append([]byte{0x21}, b...)
-	b = append(b, 0xAC)
-
-	sha := sha256.New()
-	sha.Write(b)
-	hash := sha.Sum(nil)
-
-	ripemd := ripemd160.New()
-	ripemd.Reset()
-	ripemd.Write(hash)
-	hash = ripemd.Sum(nil)
-
-	return hash, nil
+	return pk.Signature()
 }
 
 // Sign signs arbitrary length data using the private key.

pkg/wallet/wif.go

@@ -97,13 +97,14 @@ func (wif WIF) GetVerificationScript() ([]byte, error) {
 		checksig    = 0xac
 	)
 	var (
-		pubkey, vScript []byte
+		vScript []byte
+		pubkey *crypto.PublicKey
 	)
 	pubkey, err := wif.PrivateKey.PublicKey()
 	if err != nil {
 		return nil, err
 	}
-	vScript = append([]byte{pushbytes33}, pubkey...)
+	vScript = append([]byte{pushbytes33}, pubkey.Bytes()...)
 	vScript = append(vScript, checksig)
 	return vScript, nil
 }