fix: drop signature gas consumption from the gasless new-account path

Gasless txs skip fee deduction entirely, so charging gas has no economic
effect. The TxSigLimit cap alone bounds the multisig work; reverts the
NewAccountInitDecorator signature change and the SigGasConsumer wiring.

Author: 0xNilesh

app/ante/account_init_decorator.go

@@ -9,37 +9,24 @@ import (
 	"google.golang.org/protobuf/types/known/anypb"
 
 	errorsmod "cosmossdk.io/errors"
-	storetypes "cosmossdk.io/store/types"
 	txsigning "cosmossdk.io/x/tx/signing"
 	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 	"github.com/cosmos/cosmos-sdk/types/tx/signing"
 	"github.com/cosmos/cosmos-sdk/x/auth/ante"
 	authsigning "github.com/cosmos/cosmos-sdk/x/auth/signing"
-	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
 	txpolicy "github.com/pushchain/push-chain-node/app/txpolicy"
 )
 
 type AccountInitDecorator struct {
 	ak              AccountKeeper
 	signModeHandler *txsigning.HandlerMap
-	sigGasConsumer  SignatureVerificationGasConsumer
 }
 
-// SignatureVerificationGasConsumer charges gas for a single signature, matching
-// the ante.SignatureVerificationGasConsumer contract used by the SDK's
-// SigGasConsumeDecorator.
-type SignatureVerificationGasConsumer func(meter storetypes.GasMeter, sig signing.SignatureV2, params authtypes.Params) error
-
-func NewAccountInitDecorator(ak AccountKeeper, signModeHandler *txsigning.HandlerMap, sigGasConsumer SignatureVerificationGasConsumer) AccountInitDecorator {
-	if sigGasConsumer == nil {
-		sigGasConsumer = ante.DefaultSigVerificationGasConsumer
-	}
-
+func NewAccountInitDecorator(ak AccountKeeper, signModeHandler *txsigning.HandlerMap) AccountInitDecorator {
 	return AccountInitDecorator{
 		ak:              ak,
 		signModeHandler: signModeHandler,
-		sigGasConsumer:  sigGasConsumer,
 	}
 }
 
@@ -122,9 +109,11 @@ func (aid AccountInitDecorator) verifySignatureForNewAccount(ctx sdk.Context, tx
 
 	// Enforce the signature count limit before doing any verification work.
 	// This decorator short-circuits the ante chain for new accounts, so
-	// ante.ValidateSigCountDecorator never runs for them; without this an
-	// unpriced gasless tx could carry an arbitrarily large multisig key and
-	// force the node to verify every sub-signature for free.
+	// ante.ValidateSigCountDecorator never runs for them; without this hard cap
+	// a gasless tx could carry an arbitrarily large multisig key and force the
+	// node to verify every sub-signature. Gas is deliberately NOT consumed here:
+	// gasless txs skip fee deduction entirely, so charging gas would cost an
+	// attacker nothing - the count cap is what actually bounds the work.
 	sigCount := 0
 	for _, sig := range sigs {
 		if sig.PubKey == nil {
@@ -162,16 +151,6 @@ func (aid AccountInitDecorator) verifySignatureForNewAccount(ctx sdk.Context, tx
 				"pubKey does not match signer address %s with signer index: %d", sdk.AccAddress(signers[i]).String(), i)
 		}
 
-		// Charge gas for the signature, as ante.SigGasConsumeDecorator would
-		// have done had the ante chain not been short-circuited.
-		if err := aid.sigGasConsumer(ctx.GasMeter(), signing.SignatureV2{
-			PubKey:   pubKey,
-			Data:     sig.Data,
-			Sequence: sig.Sequence,
-		}, params); err != nil {
-			return err
-		}
-
 		// retrieve signer data
 		chainID := ctx.ChainID()
 		var accSequence uint64 = 0

app/ante/account_init_decorator_test.go

@@ -18,7 +18,7 @@ import (
 // gasless message type list).
 func TestAccountInitDecorator_NonGaslessTxPassesThrough(t *testing.T) {
 	ak := newMockAccountKeeperAnte(sdk.AccAddress([]byte("feeCollector")))
-	aid := ante.NewAccountInitDecorator(ak, nil /*signModeHandler not needed for non-gasless*/, nil)
+	aid := ante.NewAccountInitDecorator(ak, nil /*signModeHandler not needed for non-gasless*/)
 
 	// banktypes.MsgSend is not gasless.
 	tx := mockFeeTx{
@@ -45,7 +45,7 @@ func TestAccountInitDecorator_GaslessTxExistingAccountPassesThrough(t *testing.T
 	// Pre-register the account.
 	ak.SetAccount(context.Background(), authtypes.NewBaseAccountWithAddress(existingAddr))
 
-	aid := ante.NewAccountInitDecorator(ak, nil, nil)
+	aid := ante.NewAccountInitDecorator(ak, nil)
 
 	// Use a non-authsigning tx — the decorator skips signature verification
 	// for existing accounts only when it can parse signers. Since mockFeeTx doesn't
@@ -76,7 +76,7 @@ func TestAccountInitDecorator_GaslessTxExistingAccountPassesThrough(t *testing.T
 // tx that does not implement authsigning.Tx is rejected with ErrTxDecode.
 func TestAccountInitDecorator_NonAuthSigningTxReturnsError(t *testing.T) {
 	ak := newMockAccountKeeperAnte(sdk.AccAddress([]byte("feeCollector")))
-	aid := ante.NewAccountInitDecorator(ak, nil, nil)
+	aid := ante.NewAccountInitDecorator(ak, nil)
 
 	// MsgVoteInbound is gasless.
 	tx := mockFeeTx{

app/ante/account_init_signer_binding_test.go

@@ -18,7 +18,6 @@ import (
 	"github.com/cosmos/cosmos-sdk/types/tx/signing"
 	authsigning "github.com/cosmos/cosmos-sdk/x/auth/signing"
 	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
-	cosmosevmante "github.com/cosmos/evm/ante"
 
 	"github.com/pushchain/push-chain-node/app/ante"
 	appparams "github.com/pushchain/push-chain-node/app/params"
@@ -142,7 +141,7 @@ func buildSignedTx(t *testing.T, encCfg appparams.EncodingConfig, msg sdk.Msg, d
 func newSignerBindingDecorator(t *testing.T, encCfg appparams.EncodingConfig) (ante.AccountInitDecorator, *mockAccountKeeperAnte) {
 	t.Helper()
 	ak := newMockAccountKeeperAnte(sdk.AccAddress([]byte("feeCollector")))
-	return ante.NewAccountInitDecorator(ak, encCfg.TxConfig.SignModeHandler(), cosmosevmante.SigVerificationGasConsumer), ak
+	return ante.NewAccountInitDecorator(ak, encCfg.TxConfig.SignModeHandler()), ak
 }
 
 // TestAccountInitDecorator_RejectsAliasedModuleSigner is the regression test for
@@ -297,4 +296,3 @@ func TestAccountInitDecorator_EnforcesSignatureLimit(t *testing.T) {
 	require.True(t, sdkerrors.ErrTooManySignatures.Is(err), "expected ErrTooManySignatures, got: %v", err)
 	require.False(t, ak.HasAccount(context.Background(), signer))
 }
-

app/ante/ante_cosmos.go

@@ -44,9 +44,9 @@ func NewCosmosAnteHandler(ctx sdk.Context, options HandlerOptions) sdk.AnteHandl
 		// - this
 		// 1. generates the account for the new accounts only for gasless transactions,
 		// 2. binds the declared signer to the signing key, enforces the signature
-		//    count limit, charges signature gas and verifies the sig, and
+		//    count limit and verifies the sig, and
 		// 3. bypasses the rest of the ante chain
-		NewAccountInitDecorator(options.AccountKeeper, options.SignModeHandler, options.SigGasConsumer),
+		NewAccountInitDecorator(options.AccountKeeper, options.SignModeHandler),
 		// SetPubKeyDecorator must be called before all signature verification decorators
 		ante.NewSetPubKeyDecorator(options.AccountKeeper),
 		ante.NewValidateSigCountDecorator(options.AccountKeeper),