hermez-node/common/zk.go
common/zk.goRaw
1// Package common contains all the common data structures used at the
2// hermez-node, zk.go contains the zkSnark inputs used to generate the proof
3package common
4
5import (
6 "crypto/sha256"
7 "encoding/binary"
8 "encoding/json"
9 "fmt"
10 "math/big"
11
12 "github.com/hermeznetwork/hermez-node/log"
13 "github.com/hermeznetwork/tracerr"
14 cryptoConstants "github.com/iden3/go-iden3-crypto/constants"
15 "github.com/iden3/go-merkletree"
16 "github.com/mitchellh/mapstructure"
17)
18
19// ZKMetadata contains ZKInputs metadata that is not used directly in the
20// ZKInputs result, but to calculate values for Hash check
21type ZKMetadata struct {
22 // Circuit parameters
23 // absolute maximum of L1 or L2 transactions allowed
24 NTx uint32
25 // merkle tree depth
26 NLevels uint32
27 MaxLevels uint32
28 // absolute maximum of L1 transaction allowed
29 MaxL1Tx uint32
30 // total txs allowed
31 MaxTx uint32
32 // Maximum number of Idxs where Fees can be send in a batch (currently
33 // is constant for all circuits: 64)
34 MaxFeeIdxs uint32
35
36 L1TxsData [][]byte
37 L1TxsDataAvailability [][]byte
38 L2TxsData [][]byte
39 ChainID uint16
40
41 NewLastIdxRaw Idx
42 NewStateRootRaw *merkletree.Hash
43 NewExitRootRaw *merkletree.Hash
44}
45
46// ZKInputs represents the inputs that will be used to generate the zkSNARK proof
47type ZKInputs struct {
48 Metadata ZKMetadata `json:"-"`
49
50 //
51 // General
52 //
53
54 // CurrentNumBatch is the current batch number processed
55 CurrentNumBatch *big.Int `json:"currentNumBatch"` // uint32
56 // inputs for final `hashGlobalInputs`
57 // OldLastIdx is the last index assigned to an account
58 OldLastIdx *big.Int `json:"oldLastIdx"` // uint64 (max nLevels bits)
59 // OldStateRoot is the current state merkle tree root
60 OldStateRoot *big.Int `json:"oldStateRoot"` // Hash
61 // GlobalChainID is the blockchain ID (0 for Ethereum mainnet). This
62 // value can be get from the smart contract.
63 GlobalChainID *big.Int `json:"globalChainID"` // uint16
64 // FeeIdxs is an array of merkle tree indexes where the coordinator
65 // will receive the accumulated fees
66 FeeIdxs []*big.Int `json:"feeIdxs"` // uint64 (max nLevels bits), len: [maxFeeIdxs]
67
68 // accumulate fees
69 // FeePlanTokens contains all the tokenIDs for which the fees are being accumulated
70 FeePlanTokens []*big.Int `json:"feePlanTokens"` // uint32 (max nLevels bits), len: [maxFeeIdxs]
71
72 //
73 // Txs (L1&L2)
74 //
75
76 // transaction L1-L2
77 // TxCompressedData
78 TxCompressedData []*big.Int `json:"txCompressedData"` // big.Int (max 251 bits), len: [nTx]
79 // TxCompressedDataV2, only used in L2Txs, in L1Txs is set to 0
80 TxCompressedDataV2 []*big.Int `json:"txCompressedDataV2"` // big.Int (max 193 bits), len: [nTx]
81 // MaxNumBatch is the maximum allowed batch number when the transaction
82 // can be processed
83 MaxNumBatch []*big.Int `json:"maxNumBatch"` // uint32
84
85 // FromIdx
86 FromIdx []*big.Int `json:"fromIdx"` // uint64 (max nLevels bits), len: [nTx]
87 // AuxFromIdx is the Idx of the new created account which is consequence of a L1CreateAccountTx
88 AuxFromIdx []*big.Int `json:"auxFromIdx"` // uint64 (max nLevels bits), len: [nTx]
89
90 // ToIdx
91 ToIdx []*big.Int `json:"toIdx"` // uint64 (max nLevels bits), len: [nTx]
92 // AuxToIdx is the Idx of the Tx that has 'toIdx==0', is the
93 // coordinator who will find which Idx corresponds to the 'toBJJAy' or
94 // 'toEthAddr'
95 AuxToIdx []*big.Int `json:"auxToIdx"` // uint64 (max nLevels bits), len: [nTx]
96 // ToBJJAy
97 ToBJJAy []*big.Int `json:"toBjjAy"` // big.Int, len: [nTx]
98 // ToEthAddr
99 ToEthAddr []*big.Int `json:"toEthAddr"` // ethCommon.Address, len: [nTx]
100
101 // OnChain determines if is L1 (1/true) or L2 (0/false)
102 OnChain []*big.Int `json:"onChain"` // bool, len: [nTx]
103
104 //
105 // Txs/L1Txs
106 //
107 // NewAccount boolean (0/1) flag set 'true' when L1 tx creates a new account (fromIdx==0)
108 NewAccount []*big.Int `json:"newAccount"` // bool, len: [nTx]
109 // DepositAmountF encoded as float16
110 DepositAmountF []*big.Int `json:"loadAmountF"` // uint16, len: [nTx]
111 // FromEthAddr
112 FromEthAddr []*big.Int `json:"fromEthAddr"` // ethCommon.Address, len: [nTx]
113 // FromBJJCompressed boolean encoded where each value is a *big.Int
114 FromBJJCompressed [][256]*big.Int `json:"fromBjjCompressed"` // bool array, len: [nTx][256]
115
116 //
117 // Txs/L2Txs
118 //
119
120 // RqOffset relative transaction position to be linked. Used to perform atomic transactions.
121 RqOffset []*big.Int `json:"rqOffset"` // uint8 (max 3 bits), len: [nTx]
122
123 // transaction L2 request data
124 // RqTxCompressedDataV2
125 RqTxCompressedDataV2 []*big.Int `json:"rqTxCompressedDataV2"` // big.Int (max 251 bits), len: [nTx]
126 // RqToEthAddr
127 RqToEthAddr []*big.Int `json:"rqToEthAddr"` // ethCommon.Address, len: [nTx]
128 // RqToBJJAy
129 RqToBJJAy []*big.Int `json:"rqToBjjAy"` // big.Int, len: [nTx]
130
131 // transaction L2 signature
132 // S
133 S []*big.Int `json:"s"` // big.Int, len: [nTx]
134 // R8x
135 R8x []*big.Int `json:"r8x"` // big.Int, len: [nTx]
136 // R8y
137 R8y []*big.Int `json:"r8y"` // big.Int, len: [nTx]
138
139 //
140 // State MerkleTree Leafs transitions
141 //
142
143 // state 1, value of the sender (from) account leaf. The values at the
144 // moment pre-smtprocessor of the update (before updating the Sender
145 // leaf).
146 TokenID1 []*big.Int `json:"tokenID1"` // uint32, len: [nTx]
147 Nonce1 []*big.Int `json:"nonce1"` // uint64 (max 40 bits), len: [nTx]
148 Sign1 []*big.Int `json:"sign1"` // bool, len: [nTx]
149 Ay1 []*big.Int `json:"ay1"` // big.Int, len: [nTx]
150 Balance1 []*big.Int `json:"balance1"` // big.Int (max 192 bits), len: [nTx]
151 EthAddr1 []*big.Int `json:"ethAddr1"` // ethCommon.Address, len: [nTx]
152 Siblings1 [][]*big.Int `json:"siblings1"` // big.Int, len: [nTx][nLevels + 1]
153 // Required for inserts and deletes, values of the CircomProcessorProof (smt insert proof)
154 IsOld0_1 []*big.Int `json:"isOld0_1"` // bool, len: [nTx]
155 OldKey1 []*big.Int `json:"oldKey1"` // uint64 (max 40 bits), len: [nTx]
156 OldValue1 []*big.Int `json:"oldValue1"` // Hash, len: [nTx]
157
158 // state 2, value of the receiver (to) account leaf
159 // if Tx is an Exit, state 2 is used for the Exit Merkle Proof
160 TokenID2 []*big.Int `json:"tokenID2"` // uint32, len: [nTx]
161 Nonce2 []*big.Int `json:"nonce2"` // uint64 (max 40 bits), len: [nTx]
162 Sign2 []*big.Int `json:"sign2"` // bool, len: [nTx]
163 Ay2 []*big.Int `json:"ay2"` // big.Int, len: [nTx]
164 Balance2 []*big.Int `json:"balance2"` // big.Int (max 192 bits), len: [nTx]
165 EthAddr2 []*big.Int `json:"ethAddr2"` // ethCommon.Address, len: [nTx]
166 Siblings2 [][]*big.Int `json:"siblings2"` // big.Int, len: [nTx][nLevels + 1]
167 // newExit determines if an exit transaction has to create a new leaf in the exit tree
168 NewExit []*big.Int `json:"newExit"` // bool, len: [nTx]
169 // Required for inserts and deletes, values of the CircomProcessorProof (smt insert proof)
170 IsOld0_2 []*big.Int `json:"isOld0_2"` // bool, len: [nTx]
171 OldKey2 []*big.Int `json:"oldKey2"` // uint64 (max 40 bits), len: [nTx]
172 OldValue2 []*big.Int `json:"oldValue2"` // Hash, len: [nTx]
173
174 // state 3, value of the account leaf receiver of the Fees
175 // fee tx
176 // State fees
177 TokenID3 []*big.Int `json:"tokenID3"` // uint32, len: [maxFeeIdxs]
178 Nonce3 []*big.Int `json:"nonce3"` // uint64 (max 40 bits), len: [maxFeeIdxs]
179 Sign3 []*big.Int `json:"sign3"` // bool, len: [maxFeeIdxs]
180 Ay3 []*big.Int `json:"ay3"` // big.Int, len: [maxFeeIdxs]
181 Balance3 []*big.Int `json:"balance3"` // big.Int (max 192 bits), len: [maxFeeIdxs]
182 EthAddr3 []*big.Int `json:"ethAddr3"` // ethCommon.Address, len: [maxFeeIdxs]
183 Siblings3 [][]*big.Int `json:"siblings3"` // Hash, len: [maxFeeIdxs][nLevels + 1]
184
185 //
186 // Intermediate States
187 //
188
189 // Intermediate States to parallelize witness computation
190 // Note: the Intermediate States (IS) of the last transaction does not
191 // exist. Meaning that transaction 3 (4th) will fill the parameters
192 // FromIdx[3] and ISOnChain[3], but last transaction (nTx-1) will fill
193 // FromIdx[nTx-1] but will not fill ISOnChain. That's why IS have
194 // length of nTx-1, while the other parameters have length of nTx.
195 // Last transaction does not need intermediate state since its output
196 // will not be used.
197
198 // decode-tx
199 // ISOnChain indicates if tx is L1 (true (1)) or L2 (false (0))
200 ISOnChain []*big.Int `json:"imOnChain"` // bool, len: [nTx - 1]
201 // ISOutIdx current index account for each Tx
202 // Contains the index of the created account in case that the tx is of
203 // account creation type.
204 ISOutIdx []*big.Int `json:"imOutIdx"` // uint64 (max nLevels bits), len: [nTx - 1]
205 // rollup-tx
206 // ISStateRoot root at the moment of the Tx (once processed), the state
207 // root value once the Tx is processed into the state tree
208 ISStateRoot []*big.Int `json:"imStateRoot"` // Hash, len: [nTx - 1]
209 // ISExitTree root at the moment (once processed) of the Tx the value
210 // once the Tx is processed into the exit tree
211 ISExitRoot []*big.Int `json:"imExitRoot"` // Hash, len: [nTx - 1]
212 // ISAccFeeOut accumulated fees once the Tx is processed. Contains the
213 // array of FeeAccount Balances at each moment of each Tx processed.
214 ISAccFeeOut [][]*big.Int `json:"imAccFeeOut"` // big.Int, len: [nTx - 1][maxFeeIdxs]
215 // fee-tx:
216 // ISStateRootFee root at the moment of the Tx (once processed), the
217 // state root value once the Tx is processed into the state tree
218 ISStateRootFee []*big.Int `json:"imStateRootFee"` // Hash, len: [maxFeeIdxs - 1]
219 // ISInitStateRootFee state root once all L1-L2 tx are processed
220 // (before computing the fees-tx)
221 ISInitStateRootFee *big.Int `json:"imInitStateRootFee"` // Hash
222 // ISFinalAccFee final accumulated fees (before computing the fees-tx).
223 // Contains the final values of the ISAccFeeOut parameter
224 ISFinalAccFee []*big.Int `json:"imFinalAccFee"` // big.Int, len: [maxFeeIdxs]
225}
226
227func bigIntsToStrings(v interface{}) interface{} {
228 switch c := v.(type) {
229 case *big.Int:
230 return c.String()
231 case []*big.Int:
232 r := make([]interface{}, len(c))
233 for i := range c {
234 r[i] = bigIntsToStrings(c[i])
235 }
236 return r
237 case [256]*big.Int:
238 r := make([]interface{}, len(c))
239 for i := range c {
240 r[i] = bigIntsToStrings(c[i])
241 }
242 return r
243 case [][]*big.Int:
244 r := make([]interface{}, len(c))
245 for i := range c {
246 r[i] = bigIntsToStrings(c[i])
247 }
248 return r
249 case [][256]*big.Int:
250 r := make([]interface{}, len(c))
251 for i := range c {
252 r[i] = bigIntsToStrings(c[i])
253 }
254 return r
255 case map[string]interface{}:
256 // avoid printing a warning when there is a struct type
257 default:
258 log.Warnf("bigIntsToStrings unexpected type: %T\n", v)
259 }
260 return nil
261}
262
263// MarshalJSON implements the json marshaler for ZKInputs
264func (z ZKInputs) MarshalJSON() ([]byte, error) {
265 var m map[string]interface{}
266 dec, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
267 TagName: "json",
268 Result: &m,
269 })
270 if err != nil {
271 return nil, tracerr.Wrap(err)
272 }
273 err = dec.Decode(z)
274 if err != nil {
275 return nil, tracerr.Wrap(err)
276 }
277
278 for k, v := range m {
279 m[k] = bigIntsToStrings(v)
280 }
281 return json.Marshal(m)
282}
283
284// NewZKInputs returns a pointer to an initialized struct of ZKInputs
285func NewZKInputs(nTx, maxL1Tx, maxTx, maxFeeIdxs, nLevels uint32, currentNumBatch *big.Int) *ZKInputs {
286 zki := &ZKInputs{}
287 zki.Metadata.NTx = nTx
288 zki.Metadata.MaxFeeIdxs = maxFeeIdxs
289 zki.Metadata.MaxLevels = uint32(48) //nolint:gomnd
290 zki.Metadata.NLevels = nLevels
291 zki.Metadata.MaxL1Tx = maxL1Tx
292 zki.Metadata.MaxTx = maxTx
293
294 // General
295 zki.CurrentNumBatch = currentNumBatch
296 zki.OldLastIdx = big.NewInt(0)
297 zki.OldStateRoot = big.NewInt(0)
298 zki.GlobalChainID = big.NewInt(0) // TODO pass by parameter
299 zki.FeeIdxs = newSlice(maxFeeIdxs)
300 zki.FeePlanTokens = newSlice(maxFeeIdxs)
301
302 // Txs
303 zki.TxCompressedData = newSlice(nTx)
304 zki.TxCompressedDataV2 = newSlice(nTx)
305 zki.MaxNumBatch = newSlice(nTx)
306 zki.FromIdx = newSlice(nTx)
307 zki.AuxFromIdx = newSlice(nTx)
308 zki.ToIdx = newSlice(nTx)
309 zki.AuxToIdx = newSlice(nTx)
310 zki.ToBJJAy = newSlice(nTx)
311 zki.ToEthAddr = newSlice(nTx)
312 zki.OnChain = newSlice(nTx)
313 zki.NewAccount = newSlice(nTx)
314
315 // L1
316 zki.DepositAmountF = newSlice(nTx)
317 zki.FromEthAddr = newSlice(nTx)
318 zki.FromBJJCompressed = make([][256]*big.Int, nTx)
319 for i := 0; i < len(zki.FromBJJCompressed); i++ {
320 // zki.FromBJJCompressed[i] = newSlice(256)
321 for j := 0; j < 256; j++ {
322 zki.FromBJJCompressed[i][j] = big.NewInt(0)
323 }
324 }
325
326 // L2
327 zki.RqOffset = newSlice(nTx)
328 zki.RqTxCompressedDataV2 = newSlice(nTx)
329 zki.RqToEthAddr = newSlice(nTx)
330 zki.RqToBJJAy = newSlice(nTx)
331 zki.S = newSlice(nTx)
332 zki.R8x = newSlice(nTx)
333 zki.R8y = newSlice(nTx)
334
335 // State MerkleTree Leafs transitions
336 zki.TokenID1 = newSlice(nTx)
337 zki.Nonce1 = newSlice(nTx)
338 zki.Sign1 = newSlice(nTx)
339 zki.Ay1 = newSlice(nTx)
340 zki.Balance1 = newSlice(nTx)
341 zki.EthAddr1 = newSlice(nTx)
342 zki.Siblings1 = make([][]*big.Int, nTx)
343 for i := 0; i < len(zki.Siblings1); i++ {
344 zki.Siblings1[i] = newSlice(nLevels + 1)
345 }
346 zki.IsOld0_1 = newSlice(nTx)
347 zki.OldKey1 = newSlice(nTx)
348 zki.OldValue1 = newSlice(nTx)
349
350 zki.TokenID2 = newSlice(nTx)
351 zki.Nonce2 = newSlice(nTx)
352 zki.Sign2 = newSlice(nTx)
353 zki.Ay2 = newSlice(nTx)
354 zki.Balance2 = newSlice(nTx)
355 zki.EthAddr2 = newSlice(nTx)
356 zki.Siblings2 = make([][]*big.Int, nTx)
357 for i := 0; i < len(zki.Siblings2); i++ {
358 zki.Siblings2[i] = newSlice(nLevels + 1)
359 }
360 zki.NewExit = newSlice(nTx)
361 zki.IsOld0_2 = newSlice(nTx)
362 zki.OldKey2 = newSlice(nTx)
363 zki.OldValue2 = newSlice(nTx)
364
365 zki.TokenID3 = newSlice(maxFeeIdxs)
366 zki.Nonce3 = newSlice(maxFeeIdxs)
367 zki.Sign3 = newSlice(maxFeeIdxs)
368 zki.Ay3 = newSlice(maxFeeIdxs)
369 zki.Balance3 = newSlice(maxFeeIdxs)
370 zki.EthAddr3 = newSlice(maxFeeIdxs)
371 zki.Siblings3 = make([][]*big.Int, maxFeeIdxs)
372 for i := 0; i < len(zki.Siblings3); i++ {
373 zki.Siblings3[i] = newSlice(nLevels + 1)
374 }
375
376 // Intermediate States
377 zki.ISOnChain = newSlice(nTx - 1)
378 zki.ISOutIdx = newSlice(nTx - 1)
379 zki.ISStateRoot = newSlice(nTx - 1)
380 zki.ISExitRoot = newSlice(nTx - 1)
381 zki.ISAccFeeOut = make([][]*big.Int, nTx-1)
382 for i := 0; i < len(zki.ISAccFeeOut); i++ {
383 zki.ISAccFeeOut[i] = newSlice(maxFeeIdxs)
384 }
385 zki.ISStateRootFee = newSlice(maxFeeIdxs - 1)
386 zki.ISInitStateRootFee = big.NewInt(0)
387 zki.ISFinalAccFee = newSlice(maxFeeIdxs)
388
389 return zki
390}
391
392// newSlice returns a []*big.Int slice of length n with values initialized at
393// 0.
394// Is used to initialize all *big.Ints of the ZKInputs data structure, so when
395// the transactions are processed and the ZKInputs filled, there is no need to
396// set all the elements, and if a transaction does not use a parameter, can be
397// leaved as it is in the ZKInputs, as will be 0, so later when using the
398// ZKInputs to generate the zkSnark proof there is no 'nil'/'null' values.
399func newSlice(n uint32) []*big.Int {
400 s := make([]*big.Int, n)
401 for i := 0; i < len(s); i++ {
402 s[i] = big.NewInt(0)
403 }
404 return s
405}
406
407// HashGlobalData returns the HashGlobalData
408func (z ZKInputs) HashGlobalData() (*big.Int, error) {
409 b, err := z.ToHashGlobalData()
410 if err != nil {
411 return nil, tracerr.Wrap(err)
412 }
413
414 h := sha256.New()
415 _, err = h.Write(b)
416 if err != nil {
417 return nil, tracerr.Wrap(err)
418 }
419
420 r := new(big.Int).SetBytes(h.Sum(nil))
421 v := r.Mod(r, cryptoConstants.Q)
422
423 return v, nil
424}
425
426// ToHashGlobalData returns the data to be hashed in the method HashGlobalData
427func (z ZKInputs) ToHashGlobalData() ([]byte, error) {
428 var b []byte
429 bytesMaxLevels := int(z.Metadata.MaxLevels / 8) //nolint:gomnd
430 bytesNLevels := int(z.Metadata.NLevels / 8) //nolint:gomnd
431
432 // [MAX_NLEVELS bits] oldLastIdx
433 oldLastIdx := make([]byte, bytesMaxLevels)
434 oldLastIdxBytes := z.OldLastIdx.Bytes()
435 copy(oldLastIdx[len(oldLastIdx)-len(oldLastIdxBytes):], oldLastIdxBytes)
436 b = append(b, oldLastIdx...)
437
438 // [MAX_NLEVELS bits] newLastIdx
439 newLastIdx := make([]byte, bytesMaxLevels)
440 newLastIdxBytes, err := z.Metadata.NewLastIdxRaw.Bytes()
441 if err != nil {
442 return nil, tracerr.Wrap(err)
443 }
444 copy(newLastIdx, newLastIdxBytes[len(newLastIdxBytes)-bytesMaxLevels:])
445 b = append(b, newLastIdx...)
446
447 // [256 bits] oldStRoot
448 oldStateRoot := make([]byte, 32)
449 copy(oldStateRoot, z.OldStateRoot.Bytes())
450 b = append(b, oldStateRoot...)
451
452 // [256 bits] newStateRoot
453 newStateRoot := make([]byte, 32)
454 copy(newStateRoot, z.Metadata.NewStateRootRaw.Bytes())
455 b = append(b, newStateRoot...)
456
457 // [256 bits] newExitRoot
458 newExitRoot := make([]byte, 32)
459 copy(newExitRoot, z.Metadata.NewExitRootRaw.Bytes())
460 b = append(b, newExitRoot...)
461
462 // [MAX_L1_TX * (2 * MAX_NLEVELS + 480) bits] L1TxsData
463 l1TxDataLen := (2*z.Metadata.MaxLevels + 480)
464 l1TxsDataLen := (z.Metadata.MaxL1Tx * l1TxDataLen)
465 l1TxsData := make([]byte, l1TxsDataLen/8) //nolint:gomnd
466 for i := 0; i < len(z.Metadata.L1TxsData); i++ {
467 dataLen := int(l1TxDataLen) / 8 //nolint:gomnd
468 pos0 := i * dataLen
469 pos1 := i*dataLen + dataLen
470 copy(l1TxsData[pos0:pos1], z.Metadata.L1TxsData[i])
471 }
472 b = append(b, l1TxsData...)
473
474 var l1TxsDataAvailability []byte
475 for i := 0; i < len(z.Metadata.L1TxsDataAvailability); i++ {
476 l1TxsDataAvailability = append(l1TxsDataAvailability, z.Metadata.L1TxsDataAvailability[i]...)
477 }
478 b = append(b, l1TxsDataAvailability...)
479
480 // [MAX_TX*(2*NLevels + 24) bits] L2TxsData
481 var l2TxsData []byte
482 l2TxDataLen := 2*z.Metadata.NLevels + 24 //nolint:gomnd
483 l2TxsDataLen := (z.Metadata.MaxTx * l2TxDataLen)
484 expectedL2TxsDataLen := l2TxsDataLen / 8 //nolint:gomnd
485 for i := 0; i < len(z.Metadata.L2TxsData); i++ {
486 l2TxsData = append(l2TxsData, z.Metadata.L2TxsData[i]...)
487 }
488 if len(l2TxsData) > int(expectedL2TxsDataLen) {
489 return nil, tracerr.Wrap(fmt.Errorf("len(l2TxsData): %d, expected: %d", len(l2TxsData), expectedL2TxsDataLen))
490 }
491
492 b = append(b, l2TxsData...)
493 l2TxsPadding := make([]byte, (int(z.Metadata.MaxTx)-len(z.Metadata.L1TxsDataAvailability)-len(z.Metadata.L2TxsData))*int(l2TxDataLen)/8) //nolint:gomnd
494 b = append(b, l2TxsPadding...)
495
496 // [NLevels * MAX_TOKENS_FEE bits] feeTxsData
497 for i := 0; i < len(z.FeeIdxs); i++ {
498 feeIdx := make([]byte, bytesNLevels) //nolint:gomnd
499 feeIdxBytes := z.FeeIdxs[i].Bytes()
500 copy(feeIdx[len(feeIdx)-len(feeIdxBytes):], feeIdxBytes[:])
501 b = append(b, feeIdx...)
502 }
503
504 // [16 bits] chainID
505 var chainID [2]byte
506 binary.BigEndian.PutUint16(chainID[:], z.Metadata.ChainID)
507 b = append(b, chainID[:]...)
508
509 // [32 bits] currentNumBatch
510 currNumBatchBytes := z.CurrentNumBatch.Bytes()
511 var currNumBatch [4]byte
512 copy(currNumBatch[4-len(currNumBatchBytes):], currNumBatchBytes)
513 b = append(b, currNumBatch[:]...)
514
515 return b, nil
516}