func (k *aesPrivateKey) Symmetric() bool {
	return true
}
Symmetric returns true if this key is a symmetric key,
false if this key is asymmetric
package sw
import (
	"errors"
	"crypto/sha256"
	"github.com/inklabsfoundation/inkchain/bccsp"
)
type aesPrivateKey struct {
	privKey    []byte
	exportable bool
}
func (k *aesPrivateKey) Bytes() (raw []byte, err error) {
	if k.exportable {
		return k.privKey, nil
	}
	return nil, errors.New("Not supported.")
}
func (k *aesPrivateKey) SKI() (ski []byte) {
	hash := sha256.New()
	hash.Write([]byte{0x01})
	hash.Write(k.privKey)
	return hash.Sum(nil)
}