crypto: use PrivateKey to generate a key pair

It makes no sense to provide an API for throw-away public keys, so obtain it
via a new real keypair generation where appropriate (and that's only needed
for testing).

pkg/core/account_state_test.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"testing"
 
-	"github.com/CityOfZion/neo-go/pkg/crypto"
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/stretchr/testify/assert"
@@ -18,9 +17,11 @@ func TestDecodeEncodeAccountState(t *testing.T) {
 	)
 	for i := 0; i < n; i++ {
 		balances[randomUint256()] = util.Fixed8(int64(randomInt(1, 10000)))
-		votes[i] = &keys.PublicKey{
+		k, err := keys.NewPrivateKey()
-			ECPoint: crypto.RandomECPoint(),
+		assert.Nil(t, err)
-		}
+		p, err := k.PublicKey()
+		assert.Nil(t, err)
+		votes[i] = p
 	}
 
 	a := &AccountState{

pkg/crypto/elliptic_curve.go

@@ -5,7 +5,6 @@ package crypto
 
 import (
 	"bytes"
-	"crypto/rand"
 	"encoding/binary"
 	"encoding/hex"
 	"errors"
@@ -63,23 +62,6 @@ func NewEllipticCurve() EllipticCurve {
 	return c
 }
 
-// RandomECPoint returns a random generated ECPoint, mostly used
-// for testing.
-func RandomECPoint() ECPoint {
-	c := NewEllipticCurve()
-	b := make([]byte, c.N.BitLen()/8+8)
-	if _, err := io.ReadFull(rand.Reader, b); err != nil {
-		return ECPoint{}
-	}
-
-	d := new(big.Int).SetBytes(b)
-	d.Mod(d, new(big.Int).Sub(c.N, big.NewInt(1)))
-	d.Add(d, big.NewInt(1))
-
-	q := new(big.Int).SetBytes(d.Bytes())
-	return c.ScalarBaseMult(q)
-}
-
 // ECPointFromReader return a new point from the given reader.
 // f == 4, 6 or 7 are not implemented.
 func ECPointFromReader(r io.Reader) (point ECPoint, err error) {

pkg/crypto/keys/publickey_test.go

@@ -22,7 +22,10 @@ func TestEncodeDecodeInfinity(t *testing.T) {
 
 func TestEncodeDecodePublicKey(t *testing.T) {
 	for i := 0; i < 4; i++ {
-		p := &PublicKey{crypto.RandomECPoint()}
+		k, err := NewPrivateKey()
+		assert.Nil(t, err)
+		p, err := k.PublicKey()
+		assert.Nil(t, err)
 		buf := new(bytes.Buffer)
 		assert.Nil(t, p.EncodeBinary(buf))