wallet: don't permanently store wif in the Account

It's useless and it's just another copy of the key. If really needed, it can
be derived from the key.

pkg/wallet/account.go

@@ -24,9 +24,6 @@ type Account struct {
 	// NEO public key.
 	publicKey []byte
 
-	// Account import file.
-	wif string
-
 	// NEO public address.
 	Address string `json:"address"`
 
@@ -164,7 +161,6 @@ func (a *Account) Decrypt(passphrase string, scrypt keys.ScryptParams) error {
 	}
 
 	a.publicKey = a.privateKey.PublicKey().Bytes()
-	a.wif = a.privateKey.WIF()
 
 	return nil
 }
@@ -239,13 +235,11 @@ func (a *Account) ConvertMultisig(m int, pubs []*keys.PublicKey) error {
 func NewAccountFromPrivateKey(p *keys.PrivateKey) *Account {
 	pubKey := p.PublicKey()
 	pubAddr := p.Address()
-	wif := p.WIF()
 
 	a := &Account{
 		publicKey:  pubKey.Bytes(),
 		privateKey: p,
 		Address:    pubAddr,
-		wif:        wif,
 		Contract: &Contract{
 			Script:     pubKey.GetVerificationScript(),
 			Parameters: getContractParams(1),

pkg/wallet/account_test.go

@@ -215,7 +215,7 @@ func convertPubs(t *testing.T, hexKeys []string) []*keys.PublicKey {
 func compareFields(t *testing.T, tk keytestcases.Ktype, acc *Account) {
 	want, have := tk.Address, acc.Address
 	require.Equalf(t, want, have, "expected address %s got %s", want, have)
-	want, have = tk.Wif, acc.wif
+	want, have = tk.Wif, acc.privateKey.WIF()
 	require.Equalf(t, want, have, "expected wif %s got %s", want, have)
 	want, have = tk.PublicKey, hex.EncodeToString(acc.publicKey)
 	require.Equalf(t, want, have, "expected pub key %s got %s", want, have)

pkg/wallet/wallet_test.go

@@ -49,7 +49,6 @@ func TestAddAccount(t *testing.T) {
 	wallet.AddAccount(&Account{
 		privateKey:   nil,
 		publicKey:    nil,
-		wif:          "",
 		Address:      "real",
 		EncryptedWIF: "",
 		Label:        "",
@@ -79,7 +78,6 @@ func TestSave(t *testing.T) {
 	wallet.AddAccount(&Account{
 		privateKey:   nil,
 		publicKey:    nil,
-		wif:          "",
 		Address:      "",
 		EncryptedWIF: "",
 		Label:        "",