wallet: provide (*Account).SignHashable API

Make PrivateKey() less used and less useful.

cli/paramcontext/context.go

@@ -17,10 +17,8 @@ import (
 func InitAndSave(net netmode.Magic, tx *transaction.Transaction, acc *wallet.Account, filename string) error {
 	scCtx := context.NewParameterContext("Neo.Network.P2P.Payloads.Transaction", net, tx)
 	if acc != nil && acc.CanSign() {
-		priv := acc.PrivateKey()
+		sign := acc.SignHashable(net, tx)
-		pub := priv.PublicKey()
+		if err := scCtx.AddSignature(acc.ScriptHash(), acc.Contract, acc.PublicKey(), sign); err != nil {
-		sign := priv.SignHashable(uint32(net), tx)
-		if err := scCtx.AddSignature(acc.ScriptHash(), acc.Contract, pub, sign); err != nil {
 			return fmt.Errorf("can't add signature: %w", err)
 		}
 	}

cli/wallet/multisig.go

@@ -58,8 +58,7 @@ func signStoredTransaction(ctx *cli.Context) error {
 	}
 
 	if acc.CanSign() {
-		priv := acc.PrivateKey()
+		sign := acc.SignHashable(pc.Network, pc.Verifiable)
-		sign := priv.SignHashable(uint32(pc.Network), pc.Verifiable)
 		if err := pc.AddSignature(ch, acc.Contract, acc.PublicKey(), sign); err != nil {
 			return cli.NewExitError(fmt.Errorf("can't add signature: %w", err), 1)
 		}

pkg/neotest/signer.go

@@ -74,7 +74,7 @@ func (s *signer) ScriptHash() util.Uint160 {
 // SignHashable implements Signer interface.
 func (s *signer) SignHashable(magic uint32, item hash.Hashable) []byte {
 	return append([]byte{byte(opcode.PUSHDATA1), 64},
-		(*wallet.Account)(s).PrivateKey().SignHashable(magic, item)...)
+		(*wallet.Account)(s).SignHashable(netmode.Magic(magic), item)...)
 }
 
 // SignTx implements Signer interface.
@@ -130,7 +130,7 @@ func (m multiSigner) Script() []byte {
 func (m multiSigner) SignHashable(magic uint32, item hash.Hashable) []byte {
 	var script []byte
 	for i := 0; i < m.m; i++ {
-		sign := m.accounts[i].PrivateKey().SignHashable(magic, item)
+		sign := m.accounts[i].SignHashable(netmode.Magic(magic), item)
 		script = append(script, byte(opcode.PUSHDATA1), 64)
 		script = append(script, sign...)
 	}

pkg/rpcclient/notary/actor.go

@@ -300,7 +300,7 @@ func (a *Actor) SendRequestExactly(mainTx *transaction.Transaction, fbTx *transa
 		FallbackTransaction: fbTx,
 	}
 	req.Witness = transaction.Witness{
-		InvocationScript:   append([]byte{byte(opcode.PUSHDATA1), 64}, a.sender.PrivateKey().SignHashable(uint32(a.GetNetwork()), req)...),
+		InvocationScript:   append([]byte{byte(opcode.PUSHDATA1), 64}, a.sender.SignHashable(a.GetNetwork(), req)...),
 		VerificationScript: a.sender.GetVerificationScript(),
 	}
 	actualHash, err := a.rpc.SubmitP2PNotaryRequest(req)

pkg/rpcclient/rpc.go

@@ -938,7 +938,7 @@ func (c *Client) SignAndPushP2PNotaryRequest(mainTx *transaction.Transaction, fa
 		FallbackTransaction: fallbackTx,
 	}
 	req.Witness = transaction.Witness{
-		InvocationScript:   append([]byte{byte(opcode.PUSHDATA1), 64}, acc.PrivateKey().SignHashable(uint32(m), req)...),
+		InvocationScript:   append([]byte{byte(opcode.PUSHDATA1), 64}, acc.SignHashable(m, req)...),
 		VerificationScript: acc.GetVerificationScript(),
 	}
 	actualHash, err := c.SubmitP2PNotaryRequest(req)

pkg/services/notary/notary.go

@@ -391,7 +391,7 @@ func (n *Notary) PostPersist() {
 // finalize adds missing Notary witnesses to the transaction (main or fallback) and pushes it to the network.
 func (n *Notary) finalize(acc *wallet.Account, tx *transaction.Transaction, h util.Uint256) error {
 	notaryWitness := transaction.Witness{
-		InvocationScript:   append([]byte{byte(opcode.PUSHDATA1), 64}, acc.PrivateKey().SignHashable(uint32(n.Network), tx)...),
+		InvocationScript:   append([]byte{byte(opcode.PUSHDATA1), 64}, acc.SignHashable(n.Network, tx)...),
 		VerificationScript: []byte{},
 	}
 	for i, signer := range tx.Signers {

pkg/services/stateroot/network.go

@@ -103,7 +103,7 @@ func (s *service) sendValidatedRoot(r *state.MPTRoot, acc *wallet.Account) {
 			VerificationScript: acc.GetVerificationScript(),
 		},
 	}
-	sig := acc.PrivateKey().SignHashable(uint32(s.Network), ep)
+	sig := acc.SignHashable(s.Network, ep)
 	buf := io.NewBufBinWriter()
 	emit.Bytes(buf.BinWriter, sig)
 	ep.Witness.InvocationScript = buf.Bytes()

pkg/services/stateroot/validators.go

@@ -86,7 +86,7 @@ func (s *service) signAndSend(r *state.MPTRoot) error {
 		return nil
 	}
 
-	sig := acc.PrivateKey().SignHashable(uint32(s.Network), r)
+	sig := acc.SignHashable(s.Network, r)
 	incRoot := s.getIncompleteRoot(r.Index, myIndex)
 	incRoot.Lock()
 	defer incRoot.Unlock()
@@ -116,7 +116,7 @@ func (s *service) signAndSend(r *state.MPTRoot) error {
 			VerificationScript: acc.GetVerificationScript(),
 		},
 	}
-	sig = acc.PrivateKey().SignHashable(uint32(s.Network), e)
+	sig = acc.SignHashable(s.Network, e)
 	buf := io.NewBufBinWriter()
 	emit.Bytes(buf.BinWriter, sig)
 	e.Witness.InvocationScript = buf.Bytes()

pkg/wallet/account.go

@@ -126,6 +126,15 @@ func (a *Account) SignTx(net netmode.Magic, t *transaction.Transaction) error {
 	return nil
 }
 
+// SignHashable signs the given Hashable item and returns the signature. If this
+// account can't sign (CanSign() returns false) nil is returned.
+func (a *Account) SignHashable(net netmode.Magic, item hash.Hashable) []byte {
+	if !a.CanSign() {
+		return nil
+	}
+	return a.privateKey.SignHashable(uint32(net), item)
+}
+
 // CanSign returns true when account is not locked and has a decrypted private
 // key inside, so it's ready to create real signatures.
 func (a *Account) CanSign() bool {

pkg/wallet/account_test.go

@@ -142,6 +142,7 @@ func TestContractSignTx(t *testing.T) {
 	require.False(t, acc2.CanSign())
 	require.Error(t, acc2.SignTx(0, tx))     // Locked account.
 	require.Nil(t, acc2.PublicKey())         // Locked account.
+	require.Nil(t, acc2.SignHashable(0, tx)) // Locked account.
 
 	acc2.Locked = false
 	acc2.Close()
@@ -155,6 +156,7 @@ func TestContractSignTx(t *testing.T) {
 	})
 	require.NoError(t, acc.SignTx(0, tx)) // Add invocation script for existing witness.
 	require.Equal(t, 66, len(tx.Scripts[1].InvocationScript))
+	require.NotNil(t, acc.SignHashable(0, tx)) // Works via Hashable too.
 
 	require.NoError(t, multiAcc.SignTx(0, tx))
 	require.Equal(t, 3, len(tx.Scripts))