ZKInput with L2Txs compatible with circom circuits

- Til - update Til users BJJ key generation for better js tests compatibility - Common - PoolL2Tx to L2Tx use AuxToIdx in case that ToIdx is 0 - Update ZKInputs parameter descriptions - TxProcessor - Fix AccumulatedFees in case that there is no CoordIdx for that token - Fix zki.NewExit usage - Use same order for AccumulatedFees & FeeIdx & FeePlanTokens - Add Nonce usage to ExitLeafs - Update TestZKInput6 and check its compatibility with circom Hermez circuits
2026-02-07 03:16:45 +01:00 · 2021-01-07 18:32:09 +01:00
parent b0e925fd71
commit b59710a149
10 changed files with 247 additions and 73 deletions
--- a/common/pooll2tx.go
+++ b/common/pooll2tx.go
@@ -311,10 +311,16 @@ func (tx *PoolL2Tx) VerifySignature(chainID uint16, pkComp babyjub.PublicKeyComp

 // L2Tx returns a *L2Tx from the PoolL2Tx
 func (tx PoolL2Tx) L2Tx() L2Tx {
+	var toIdx Idx
+	if tx.ToIdx == Idx(0) {
+		toIdx = tx.AuxToIdx
+	} else {
+		toIdx = tx.ToIdx
+	}
 	return L2Tx{
 		TxID:    tx.TxID,
 		FromIdx: tx.FromIdx,
-		ToIdx:   tx.ToIdx,
+		ToIdx:   toIdx,
 		Amount:  tx.Amount,
 		Fee:     tx.Fee,
 		Nonce:   tx.Nonce,
--- a/common/zk.go
+++ b/common/zk.go
@@ -42,7 +42,8 @@ type ZKMetadata struct {
 	NewExitRootRaw  *merkletree.Hash
 }

-// ZKInputs represents the inputs that will be used to generate the zkSNARK proof
+// ZKInputs represents the inputs that will be used to generate the zkSNARK
+// proof
 type ZKInputs struct {
 	Metadata ZKMetadata `json:"-"`

@@ -60,12 +61,16 @@ type ZKInputs struct {
 	// GlobalChainID is the blockchain ID (0 for Ethereum mainnet). This
 	// value can be get from the smart contract.
 	GlobalChainID *big.Int `json:"globalChainID"` // uint16
-	// FeeIdxs is an array of merkle tree indexes where the coordinator
-	// will receive the accumulated fees
+	// FeeIdxs is an array of merkle tree indexes (Idxs) where the
+	// coordinator will receive the accumulated fees
 	FeeIdxs []*big.Int `json:"feeIdxs"` // uint64 (max nLevels bits), len: [maxFeeIdxs]

 	// accumulate fees
-	// FeePlanTokens contains all the tokenIDs for which the fees are being accumulated
+	// FeePlanTokens contains all the tokenIDs for which the fees are being
+	// accumulated and those fees accoumulated will be paid to the FeeIdxs
+	// array.  The order of FeeIdxs & FeePlanTokens & State3 must match.
+	// Coordinator fees are processed correlated such as:
+	// [FeePlanTokens[i], FeeIdxs[i]]
 	FeePlanTokens []*big.Int `json:"feePlanTokens"` // uint32 (max nLevels bits), len: [maxFeeIdxs]

 	//
@@ -79,11 +84,12 @@ type ZKInputs struct {
 	TxCompressedDataV2 []*big.Int `json:"txCompressedDataV2"` // big.Int (max 193 bits), len: [maxTx]
 	// MaxNumBatch is the maximum allowed batch number when the transaction
 	// can be processed
-	MaxNumBatch []*big.Int `json:"maxNumBatch"` // uint32
+	MaxNumBatch []*big.Int `json:"maxNumBatch"` // big.Int (max 32 bits), len: [maxTx]

 	// FromIdx
 	FromIdx []*big.Int `json:"fromIdx"` // uint64 (max nLevels bits), len: [maxTx]
-	// AuxFromIdx is the Idx of the new created account which is consequence of a L1CreateAccountTx
+	// AuxFromIdx is the Idx of the new created account which is
+	// consequence of a L1CreateAccountTx
 	AuxFromIdx []*big.Int `json:"auxFromIdx"` // uint64 (max nLevels bits), len: [maxTx]

 	// ToIdx
@@ -103,7 +109,8 @@ type ZKInputs struct {
 	//
 	// Txs/L1Txs
 	//
-	// NewAccount boolean (0/1) flag set 'true' when L1 tx creates a new account (fromIdx==0)
+	// NewAccount boolean (0/1) flag set 'true' when L1 tx creates a new
+	// account (fromIdx==0)
 	NewAccount []*big.Int `json:"newAccount"` // bool, len: [maxTx]
 	// DepositAmountF encoded as float16
 	DepositAmountF []*big.Int `json:"loadAmountF"` // uint16, len: [maxTx]
@@ -116,7 +123,8 @@ type ZKInputs struct {
 	// Txs/L2Txs
 	//

-	// RqOffset relative transaction position to be linked. Used to perform atomic transactions.
+	// RqOffset relative transaction position to be linked. Used to perform
+	// atomic transactions.
 	RqOffset []*big.Int `json:"rqOffset"` // uint8 (max 3 bits), len: [maxTx]

 	// transaction L2 request data
@@ -149,13 +157,17 @@ type ZKInputs struct {
 	Balance1  []*big.Int   `json:"balance1"`  // big.Int (max 192 bits), len: [maxTx]
 	EthAddr1  []*big.Int   `json:"ethAddr1"`  // ethCommon.Address, len: [maxTx]
 	Siblings1 [][]*big.Int `json:"siblings1"` // big.Int, len: [maxTx][nLevels + 1]
-	// Required for inserts and deletes, values of the CircomProcessorProof (smt insert proof)
+	// Required for inserts and deletes, values of the CircomProcessorProof
+	// (smt insert proof)
 	IsOld0_1  []*big.Int `json:"isOld0_1"`  // bool, len: [maxTx]
 	OldKey1   []*big.Int `json:"oldKey1"`   // uint64 (max 40 bits), len: [maxTx]
 	OldValue1 []*big.Int `json:"oldValue1"` // Hash, len: [maxTx]

-	// state 2, value of the receiver (to) account leaf
-	// if Tx is an Exit, state 2 is used for the Exit Merkle Proof
+	// state 2, value of the receiver (to) account leaf. The values at the
+	// moment pre-smtprocessor of the update (before updating the Receiver
+	// leaf).
+	// If Tx is an Exit (tx.ToIdx=1), state 2 is used for the Exit Merkle
+	// Proof of the Exit MerkleTree.
 	TokenID2  []*big.Int   `json:"tokenID2"`  // uint32, len: [maxTx]
 	Nonce2    []*big.Int   `json:"nonce2"`    // uint64 (max 40 bits), len: [maxTx]
 	Sign2     []*big.Int   `json:"sign2"`     // bool, len: [maxTx]
@@ -163,16 +175,22 @@ type ZKInputs struct {
 	Balance2  []*big.Int   `json:"balance2"`  // big.Int (max 192 bits), len: [maxTx]
 	EthAddr2  []*big.Int   `json:"ethAddr2"`  // ethCommon.Address, len: [maxTx]
 	Siblings2 [][]*big.Int `json:"siblings2"` // big.Int, len: [maxTx][nLevels + 1]
-	// newExit determines if an exit transaction has to create a new leaf in the exit tree
+	// NewExit determines if an exit transaction has to create a new leaf
+	// in the exit tree. If already exists an exit leaf of an account in
+	// the ExitTree, there is no 'new leaf' creation and 'NewExit' for that
+	// tx is 0 (if is an 'insert' in the tree, NewExit=1, if is an 'update'
+	// of an existing leaf, NewExit=0).
 	NewExit []*big.Int `json:"newExit"` // bool, len: [maxTx]
-	// Required for inserts and deletes, values of the CircomProcessorProof (smt insert proof)
+	// Required for inserts and deletes, values of the CircomProcessorProof
+	// (smt insert proof)
 	IsOld0_2  []*big.Int `json:"isOld0_2"`  // bool, len: [maxTx]
 	OldKey2   []*big.Int `json:"oldKey2"`   // uint64 (max 40 bits), len: [maxTx]
 	OldValue2 []*big.Int `json:"oldValue2"` // Hash, len: [maxTx]

-	// state 3, value of the account leaf receiver of the Fees
-	// fee tx
-	// State fees
+	// state 3, fee leafs states, value of the account leaf receiver of the
+	// Fees fee tx. The values at the moment pre-smtprocessor of the update
+	// (before updating the Receiver leaf).
+	// The order of FeeIdxs & FeePlanTokens & State3 must match.
 	TokenID3  []*big.Int   `json:"tokenID3"`  // uint32, len: [maxFeeIdxs]
 	Nonce3    []*big.Int   `json:"nonce3"`    // uint64 (max 40 bits), len: [maxFeeIdxs]
 	Sign3     []*big.Int   `json:"sign3"`     // bool, len: [maxFeeIdxs]
--- a/test/til/sets.go
+++ b/test/til/sets.go
@@ -224,7 +224,6 @@ CreateAccountDeposit(1) C: 0
 // close Block:0, Batch:1
 > batchL1 // freeze L1User{2}, forge L1Coord{0}
 // Expected balances:
-//     Coord(0): 0, Coord(1): 0
 //     C(0): 0

 CreateAccountDeposit(1) A: 500
@@ -232,14 +231,12 @@ CreateAccountDeposit(1) A: 500
 // close Block:0, Batch:2
 > batchL1 // freeze L1User{1}, forge L1User{2}
 // Expected balances:
-//     Coord(0): 0, Coord(1): 0
 //     A(0): 500
 //     C(0): 0, C(1): 0

 // close Block:0, Batch:3
 > batchL1 // freeze L1User{nil}, forge L1User{1}
 // Expected balances:
-//     Coord(0): 0, Coord(1): 0
 //     A(0): 500, A(1): 500
 //     C(0): 0

@@ -253,7 +250,6 @@ CreateAccountDeposit(0) D: 800
 // close Block:0, Batch:5
 > batchL1 // freeze L1User{1}, forge L1User{1}
 // Expected balances:
-//     Coord(0): 0, Coord(1): 0
 //     A(0): 600, A(1): 500
 //     B(0): 400
 //     C(0): 0
--- a/test/til/txs.go
+++ b/test/til/txs.go
@@ -2,9 +2,9 @@ package til

 import (
 	"crypto/ecdsa"
+	"encoding/binary"
 	"fmt"
 	"math/big"
-	"strconv"
 	"strings"
 	"time"

@@ -694,7 +694,9 @@ func (tc *Context) generateKeys(userNames []string) {
 		}
 		// babyjubjub key
 		var sk babyjub.PrivateKey
-		copy(sk[:], []byte(strconv.Itoa(i))) // only for testing
+		var iBytes [8]byte
+		binary.LittleEndian.PutUint64(iBytes[:], uint64(i))
+		copy(sk[:], iBytes[:]) // only for testing

 		// eth address
 		var key ecdsa.PrivateKey
--- a/test/til/txs_test.go
+++ b/test/til/txs_test.go
@@ -1,14 +1,34 @@
 package til

 import (
+	"encoding/hex"
+	"fmt"
 	"math/big"
 	"testing"

+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/hermeznetwork/hermez-node/common"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )

+func TestGenerateKeys(t *testing.T) {
+	tc := NewContext(0, common.RollupConstMaxL1UserTx)
+	usernames := []string{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"}
+	tc.generateKeys(usernames)
+	debug := false
+	if debug {
+		for i, username := range usernames {
+			fmt.Println(i, username)
+			sk := crypto.FromECDSA(tc.Users[username].EthSk)
+			fmt.Println("	eth_sk", hex.EncodeToString(sk))
+			fmt.Println("	eth_addr", tc.Users[username].Addr)
+			fmt.Println("	bjj_sk", hex.EncodeToString(tc.Users[username].BJJ[:]))
+			fmt.Println("	bjj_pub", tc.Users[username].BJJ.Public().Compress())
+		}
+	}
+}
+
 func TestGenerateBlocksNoBatches(t *testing.T) {
 	set := `
 		Type: Blockchain
--- a/txprocessor/txprocessor.go
+++ b/txprocessor/txprocessor.go
@@ -274,7 +274,8 @@ func (tp *TxProcessor) ProcessTxs(coordIdxs []common.Idx, l1usertxs, l1coordinat
 			if tp.i < nTx-1 {
 				tp.zki.ISOutIdx[tp.i] = tp.s.CurrentIdx().BigInt()
 				tp.zki.ISStateRoot[tp.i] = tp.s.MT.Root().BigInt()
-				tp.zki.ISAccFeeOut[tp.i] = formatAccumulatedFees(collectedFees, tp.zki.FeePlanTokens)
+				// tp.zki.ISAccFeeOut[tp.i] = formatAccumulatedFees(collectedFees, tp.zki.FeePlanTokens)
+				tp.zki.ISAccFeeOut[tp.i] = formatAccumulatedFees(collectedFees, tp.zki.FeePlanTokens, coordIdxs)
 				if exitIdx == nil {
 					tp.zki.ISExitRoot[tp.i] = exitTree.Root().BigInt()
 				}
@@ -302,14 +303,14 @@ func (tp *TxProcessor) ProcessTxs(coordIdxs []common.Idx, l1usertxs, l1coordinat
 			if i < int(tp.config.MaxTx)-1 {
 				tp.zki.ISOutIdx[i] = tp.s.CurrentIdx().BigInt()
 				tp.zki.ISStateRoot[i] = tp.s.MT.Root().BigInt()
-				tp.zki.ISAccFeeOut[i] = formatAccumulatedFees(collectedFees, tp.zki.FeePlanTokens)
+				tp.zki.ISAccFeeOut[i] = formatAccumulatedFees(collectedFees, tp.zki.FeePlanTokens, coordIdxs)
 				tp.zki.ISExitRoot[i] = exitTree.Root().BigInt()
 			}
 			if i >= tp.i {
 				tp.zki.TxCompressedData[i] = new(big.Int).SetBytes(common.SignatureConstantBytes)
 			}
 		}
-		isFinalAccFee := formatAccumulatedFees(collectedFees, tp.zki.FeePlanTokens)
+		isFinalAccFee := formatAccumulatedFees(collectedFees, tp.zki.FeePlanTokens, coordIdxs)
 		copy(tp.zki.ISFinalAccFee, isFinalAccFee)
 		// before computing the Fees txs, set the ISInitStateRootFee
 		tp.zki.ISInitStateRootFee = tp.s.MT.Root().BigInt()
@@ -318,7 +319,9 @@ func (tp *TxProcessor) ProcessTxs(coordIdxs []common.Idx, l1usertxs, l1coordinat
 	// distribute the AccumulatedFees from the processed L2Txs into the
 	// Coordinator Idxs
 	iFee := 0
-	for idx, accumulatedFee := range tp.AccumulatedFees {
+	for _, idx := range coordIdxs {
+		accumulatedFee := tp.AccumulatedFees[idx]
+
 		cmp := accumulatedFee.Cmp(big.NewInt(0))
 		if cmp == 1 { // accumulatedFee>0
 			// send the fee to the Idx of the Coordinator for the TokenID
@@ -816,7 +819,7 @@ func (tp *TxProcessor) applyTransfer(coordIdxsMap map[common.TokenID]common.Idx,
 		tp.zki.Balance1[tp.i] = accSender.Balance
 		tp.zki.EthAddr1[tp.i] = common.EthAddrToBigInt(accSender.EthAddr)
 	}
-	if !tx.IsL1 {
+	if !tx.IsL1 { // L2
 		// increment nonce
 		accSender.Nonce++

@@ -1009,8 +1012,6 @@ func (tp *TxProcessor) applyExit(coordIdxsMap map[common.TokenID]common.Idx,
 		tp.zki.Ay1[tp.i] = accBJJY
 		tp.zki.Balance1[tp.i] = acc.Balance
 		tp.zki.EthAddr1[tp.i] = common.EthAddrToBigInt(acc.EthAddr)
-
-		tp.zki.NewExit[tp.i] = big.NewInt(1)
 	}

 	if !tx.IsL1 {
@@ -1081,6 +1082,8 @@ func (tp *TxProcessor) applyExit(coordIdxsMap map[common.TokenID]common.Idx,
 			tp.zki.Ay2[tp.i] = accBJJY
 			tp.zki.Balance2[tp.i] = tx.Amount
 			tp.zki.EthAddr2[tp.i] = common.EthAddrToBigInt(acc.EthAddr)
+			// as Leaf didn't exist in the ExitTree, set NewExit[i]=1
+			tp.zki.NewExit[tp.i] = big.NewInt(1)
 		}
 		p, err = statedb.CreateAccountInTreeDB(exitTree.DB(), exitTree, tx.FromIdx, exitAccount)
 		if err != nil {
@@ -1099,12 +1102,14 @@ func (tp *TxProcessor) applyExit(coordIdxsMap map[common.TokenID]common.Idx,
 	} else if err != nil {
 		return exitAccount, false, tracerr.Wrap(err)
 	}
+	exitAccount.Nonce = exitAccount.Nonce + 1

 	// 1b. if idx already exist in exitTree:
 	if tp.zki != nil {
 		// Set the State2 before updating the Exit leaf
 		tp.zki.TokenID2[tp.i] = acc.TokenID.BigInt()
-		tp.zki.Nonce2[tp.i] = big.NewInt(0)
+		// increment nonce from existing ExitLeaf
+		tp.zki.Nonce2[tp.i] = exitAccount.Nonce.BigInt()
 		accBJJSign, accBJJY := babyjub.UnpackSignY(acc.BJJ)
 		if accBJJSign {
 			tp.zki.Sign2[tp.i] = big.NewInt(1)
--- a/txprocessor/txprocessor_test.go
+++ b/txprocessor/txprocessor_test.go
@@ -226,12 +226,14 @@ func TestProcessTxsBalances(t *testing.T) {
 	log.Debug("block:0 batch:0, only L1CoordinatorTxs")
 	_, err = tp.ProcessTxs(nil, nil, blocks[0].Rollup.Batches[0].L1CoordinatorTxs, nil)
 	require.NoError(t, err)
+	assert.Equal(t, "0", tp.s.MT.Root().BigInt().String())

 	log.Debug("block:0 batch:1")
 	l1UserTxs := []common.L1Tx{}
 	l2Txs := common.L2TxsToPoolL2Txs(blocks[0].Rollup.Batches[1].L2Txs)
 	_, err = tp.ProcessTxs(nil, l1UserTxs, blocks[0].Rollup.Batches[1].L1CoordinatorTxs, l2Txs)
 	require.NoError(t, err)
+	assert.Equal(t, "0", tp.s.MT.Root().BigInt().String())

 	log.Debug("block:0 batch:2")
 	l1UserTxs = til.L1TxsToCommonL1Txs(tc.Queues[*blocks[0].Rollup.Batches[2].Batch.ForgeL1TxsNum])
@@ -239,6 +241,7 @@ func TestProcessTxsBalances(t *testing.T) {
 	_, err = tp.ProcessTxs(nil, l1UserTxs, blocks[0].Rollup.Batches[2].L1CoordinatorTxs, l2Txs)
 	require.NoError(t, err)
 	checkBalance(t, tc, sdb, "A", 0, "500")
+	assert.Equal(t, "13644148972047617726265275926674266298636745191961029124811988256139761111521", tp.s.MT.Root().BigInt().String())

 	log.Debug("block:0 batch:3")
 	l1UserTxs = til.L1TxsToCommonL1Txs(tc.Queues[*blocks[0].Rollup.Batches[3].Batch.ForgeL1TxsNum])
@@ -247,6 +250,7 @@ func TestProcessTxsBalances(t *testing.T) {
 	require.NoError(t, err)
 	checkBalance(t, tc, sdb, "A", 0, "500")
 	checkBalance(t, tc, sdb, "A", 1, "500")
+	assert.Equal(t, "12433441613247342495680642890662773367605896324555599297255745922589338651261", tp.s.MT.Root().BigInt().String())

 	log.Debug("block:0 batch:4")
 	l1UserTxs = til.L1TxsToCommonL1Txs(tc.Queues[*blocks[0].Rollup.Batches[4].Batch.ForgeL1TxsNum])
@@ -255,6 +259,7 @@ func TestProcessTxsBalances(t *testing.T) {
 	require.NoError(t, err)
 	checkBalance(t, tc, sdb, "A", 0, "500")
 	checkBalance(t, tc, sdb, "A", 1, "500")
+	assert.Equal(t, "12433441613247342495680642890662773367605896324555599297255745922589338651261", tp.s.MT.Root().BigInt().String())

 	log.Debug("block:0 batch:5")
 	l1UserTxs = til.L1TxsToCommonL1Txs(tc.Queues[*blocks[0].Rollup.Batches[5].Batch.ForgeL1TxsNum])
@@ -264,6 +269,7 @@ func TestProcessTxsBalances(t *testing.T) {
 	checkBalance(t, tc, sdb, "A", 0, "600")
 	checkBalance(t, tc, sdb, "A", 1, "500")
 	checkBalance(t, tc, sdb, "B", 0, "400")
+	assert.Equal(t, "4191361650490017591061467288209836928064232431729236465872209988325272262963", tp.s.MT.Root().BigInt().String())

 	coordIdxs := []common.Idx{261, 262}
 	log.Debug("block:0 batch:6")
@@ -279,6 +285,7 @@ func TestProcessTxsBalances(t *testing.T) {
 	checkBalance(t, tc, sdb, "B", 1, "200")
 	checkBalance(t, tc, sdb, "C", 0, "100")
 	checkBalance(t, tc, sdb, "D", 0, "800")
+	assert.Equal(t, "7614010373759339299470010949167613050707822522530721724565424494781010548240", tp.s.MT.Root().BigInt().String())

 	log.Debug("block:0 batch:7")
 	l1UserTxs = til.L1TxsToCommonL1Txs(tc.Queues[*blocks[0].Rollup.Batches[7].Batch.ForgeL1TxsNum])
@@ -294,6 +301,7 @@ func TestProcessTxsBalances(t *testing.T) {
 	checkBalance(t, tc, sdb, "C", 0, "45")
 	checkBalance(t, tc, sdb, "C", 1, "100")
 	checkBalance(t, tc, sdb, "D", 0, "800")
+	assert.Equal(t, "21231789250434471575486264439945776732824482207853465397552873521865656677689", tp.s.MT.Root().BigInt().String())

 	log.Debug("block:1 batch:0")
 	l1UserTxs = til.L1TxsToCommonL1Txs(tc.Queues[*blocks[1].Rollup.Batches[0].Batch.ForgeL1TxsNum])
@@ -309,12 +317,14 @@ func TestProcessTxsBalances(t *testing.T) {
 	checkBalance(t, tc, sdb, "C", 0, "845")
 	checkBalance(t, tc, sdb, "C", 1, "100")
 	checkBalance(t, tc, sdb, "D", 0, "470")
+	assert.Equal(t, "11289313644810782435120113035387729451095637380468777086895109386127538554246", tp.s.MT.Root().BigInt().String())

 	log.Debug("block:1 batch:1")
 	l1UserTxs = til.L1TxsToCommonL1Txs(tc.Queues[*blocks[1].Rollup.Batches[1].Batch.ForgeL1TxsNum])
 	l2Txs = common.L2TxsToPoolL2Txs(blocks[1].Rollup.Batches[1].L2Txs)
 	_, err = tp.ProcessTxs(coordIdxs, l1UserTxs, blocks[1].Rollup.Batches[1].L1CoordinatorTxs, l2Txs)
 	require.NoError(t, err)
+	assert.Equal(t, "10342681351319338354912862547249967104198317571995055517008223832276478908482", tp.s.MT.Root().BigInt().String())

 	// use Set of PoolL2 txs
 	poolL2Txs, err := tc.GeneratePoolL2Txs(til.SetPoolL2MinimumFlow1)
@@ -553,7 +563,7 @@ func TestProcessTxsBatchBuilder(t *testing.T) {
 	assert.Equal(t, common.TokenID(1), acc.TokenID)
 	assert.Equal(t, "2", acc.Balance.String())

-	assert.Equal(t, "2720257526434001367979405991743527513807903085728407823609738212616896104498", sdb.MT.Root().BigInt().String())
+	assert.Equal(t, "18894163991492573893706613133132363559300580460789469708968288074813925659539", sdb.MT.Root().BigInt().String())
 }

 func TestProcessTxsRootTestVectors(t *testing.T) {
--- a/txprocessor/utils.go
+++ b/txprocessor/utils.go
@@ -36,14 +36,16 @@ func BJJCompressedTo256BigInts(pkComp babyjub.PublicKeyComp) [256]*big.Int {
 // formatAccumulatedFees returns an array of [nFeeAccounts]*big.Int containing
 // the balance of each FeeAccount, taken from the 'collectedFees' map, in the
 // order of the 'orderTokenIDs'
-func formatAccumulatedFees(collectedFees map[common.TokenID]*big.Int, orderTokenIDs []*big.Int) []*big.Int {
+// func formatAccumulatedFees(collectedFees map[common.TokenID]*big.Int, orderTokenIDs []*big.Int) []*big.Int {
+func formatAccumulatedFees(collectedFees map[common.TokenID]*big.Int, orderTokenIDs []*big.Int, coordIdxs []common.Idx) []*big.Int {
 	accFeeOut := make([]*big.Int, len(orderTokenIDs))
-	for i := 0; i < len(orderTokenIDs); i++ {
+	for i := 0; i < len(accFeeOut); i++ {
+		accFeeOut[i] = big.NewInt(0)
+	}
+	for i := 0; i < len(coordIdxs); i++ {
 		tokenID := common.TokenIDFromBigInt(orderTokenIDs[i])
 		if _, ok := collectedFees[tokenID]; ok {
 			accFeeOut[i] = new(big.Int).Set(collectedFees[tokenID])
-		} else {
-			accFeeOut[i] = big.NewInt(0)
 		}
 	}
 	return accFeeOut
--- a/txprocessor/zkinputsgen_test.go
+++ b/txprocessor/zkinputsgen_test.go
--- a/txselector/txselector_test.go
+++ b/txselector/txselector_test.go
@@ -303,7 +303,7 @@ func TestGetL2TxSelectionMinimumFlow0(t *testing.T) {
 	require.NoError(t, err)

 	log.Debug("block:0 batch:7")
-	// simulate the PoolL2Txs of the batch6
+	// simulate the PoolL2Txs of the batch7
 	batchPoolL2 = `
 	Type: PoolL2
 	PoolTransfer(0) A-B: 100 (126)