diff --git a/cmd/playground/main.go b/cmd/playground/main.go
new file mode 100644
index 000000000..61c6aa474
--- /dev/null
+++ b/cmd/playground/main.go
@@ -0,0 +1,83 @@
+package main
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"flag"
+	"fmt"
+	"log"
+	"strings"
+
+	"go.vocdoni.io/dvote/util"
+)
+
+func main() {
+	strInputList := flag.String("inputs", "", "inputs parts")
+	strExpected := flag.String("raw", "", "expected raw")
+	flag.Parse()
+
+	if *strInputList == "" {
+		log.Fatal("inputs is required")
+	}
+	inputList := strings.Split(*strInputList, ",")
+	if len(inputList) != 2 {
+		log.Fatal("inputs is required, and must be a comma separated list of two big ints")
+	}
+	if *strExpected == "" {
+		log.Fatal("raw expected is required")
+	}
+	rawExpected, err := hex.DecodeString(*strExpected)
+	if err != nil {
+		log.Fatalf("error decoding vote package: %s", err)
+	}
+	expectedHash := sha256.Sum256(rawExpected)
+
+	rebuildHash := util.SplittedArboStrToBytes(inputList[0], inputList[1], false, false)
+	fmt.Println("")
+	fmt.Println("Without swap endianess and lazy")
+	fmt.Println("")
+	fmt.Println("- Provided raw", hex.EncodeToString(rawExpected), len(rawExpected))
+	fmt.Println("")
+	fmt.Println("- Rebuild hash", hex.EncodeToString(rebuildHash), len(rebuildHash))
+	fmt.Println("")
+	fmt.Println("- Calculated hash", hex.EncodeToString(expectedHash[:]), len(expectedHash[:]))
+	fmt.Println("")
+	fmt.Println("- Match?", bytes.Equal(rebuildHash, expectedHash[:]))
+	fmt.Println("")
+
+	rebuildHash = util.SplittedArboStrToBytes(inputList[0], inputList[1], true, false)
+	fmt.Println("With swap endianess and lazy")
+	fmt.Println("")
+	fmt.Println("- Provided raw", hex.EncodeToString(rawExpected), len(rawExpected))
+	fmt.Println("")
+	fmt.Println("- Rebuild hash", hex.EncodeToString(rebuildHash), len(rebuildHash))
+	fmt.Println("")
+	fmt.Println("- Calculated hash", hex.EncodeToString(expectedHash[:]), len(expectedHash[:]))
+	fmt.Println("")
+	fmt.Println("- Match?", bytes.Equal(rebuildHash, expectedHash[:]))
+
+	rebuildHash = util.SplittedArboStrToBytes(inputList[0], inputList[1], false, true)
+	fmt.Println("")
+	fmt.Println("Without swap endianess and strict")
+	fmt.Println("")
+	fmt.Println("- Provided raw", hex.EncodeToString(rawExpected), len(rawExpected))
+	fmt.Println("")
+	fmt.Println("- Rebuild hash", hex.EncodeToString(rebuildHash), len(rebuildHash))
+	fmt.Println("")
+	fmt.Println("- Calculated hash", hex.EncodeToString(expectedHash[:]), len(expectedHash[:]))
+	fmt.Println("")
+	fmt.Println("- Match?", bytes.Equal(rebuildHash, expectedHash[:]))
+	fmt.Println("")
+
+	rebuildHash = util.SplittedArboStrToBytes(inputList[0], inputList[1], true, true)
+	fmt.Println("With swap endianess and strict")
+	fmt.Println("")
+	fmt.Println("- Provided raw", hex.EncodeToString(rawExpected), len(rawExpected))
+	fmt.Println("")
+	fmt.Println("- Rebuild hash", hex.EncodeToString(rebuildHash), len(rebuildHash))
+	fmt.Println("")
+	fmt.Println("- Calculated hash", hex.EncodeToString(expectedHash[:]), len(expectedHash[:]))
+	fmt.Println("")
+	fmt.Println("- Match?", bytes.Equal(rebuildHash, expectedHash[:]))
+}
diff --git a/crypto/zk/prover/pubsignals.go b/crypto/zk/prover/pubsignals.go
index 1aa769397..fd581b308 100644
--- a/crypto/zk/prover/pubsignals.go
+++ b/crypto/zk/prover/pubsignals.go
@@ -42,20 +42,23 @@ func (p *Proof) ElectionID() ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	return util.SplittedArboStrToBytes(electionID1str, electionID2str), nil
+	return util.SplittedArboStrToBytes(electionID1str, electionID2str, false, true), nil
 }
 
 // VoteHash returns the VoteHash included into the current proof.
-func (p *Proof) VoteHash() ([]byte, error) {
+func (p *Proof) VoteHash() ([]byte, []string, error) {
 	voteHash1str, err := p.extractPubSignal("voteHash[0]")
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	voteHash2str, err := p.extractPubSignal("voteHash[1]")
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
-	return util.SplittedArboStrToBytes(voteHash1str, voteHash2str), nil
+	return util.SplittedArboStrToBytes(voteHash1str, voteHash2str, false, true), []string{
+		voteHash1str,
+		voteHash2str,
+	}, nil
 }
 
 // CensusRoot returns the CensusRoot included into the current proof.
diff --git a/util/zk.go b/util/zk.go
index e797fdd4b..c6e7187ee 100644
--- a/util/zk.go
+++ b/util/zk.go
@@ -43,25 +43,31 @@ func BytesToArboSplitStr(input []byte) []string {
 }
 
 // SplittedArboToBytes function receives a slice of big.Int's and returns the
-func SplittedArboToBytes(input1, input2 *big.Int) []byte {
+func SplittedArboToBytes(input1, input2 *big.Int, swap, strict bool) []byte {
 	// when the last bytes are 0, the SwapEndianness function removes them
 	// so we need to add them back until we have 16 bytes in both parts
-	b1 := arbo.SwapEndianness(input1.Bytes())
-	for len(b1) < 16 {
-		b1 = append(b1, 0)
+	b1 := input1.Bytes()
+	b2 := input2.Bytes()
+	if swap {
+		b1 = arbo.SwapEndianness(b1)
+		b2 = arbo.SwapEndianness(b2)
 	}
-	b2 := arbo.SwapEndianness(input2.Bytes())
-	for len(b2) < 16 {
-		b2 = append(b2, 0)
+	if strict {
+		for len(b1) < 16 {
+			b1 = append([]byte{0}, b1...)
+		}
+		for len(b2) < 16 {
+			b2 = append([]byte{0}, b2...)
+		}
 	}
 	return append(b1, b2...)
 }
 
 // SplittedArboStrToBytes function wraps SplittedArboToBytes to return the input as []byte
-func SplittedArboStrToBytes(input1, input2 string) []byte {
+func SplittedArboStrToBytes(input1, input2 string, swap, strict bool) []byte {
 	b1 := new(big.Int)
 	b1.SetString(input1, 10)
 	b2 := new(big.Int)
 	b2.SetString(input2, 10)
-	return SplittedArboToBytes(b1, b2)
+	return SplittedArboToBytes(b1, b2, swap, strict)
 }
diff --git a/util/zk_test.go b/util/zk_test.go
index b7a1e0360..08f501b53 100644
--- a/util/zk_test.go
+++ b/util/zk_test.go
@@ -22,17 +22,13 @@ func TestBytesToArboStr(t *testing.T) {
 }
 
 func TestConversionConsistency(t *testing.T) {
-	originalInput := []byte("test input")
-
+	originalInput := RandomBytes(20)
 	// Convert to strings
 	strParts := BytesToArboSplitStr(originalInput)
-
 	// Convert strings back to bytes
-	reconstructedBytes := SplittedArboStrToBytes(strParts[0], strParts[1])
-
+	reconstructedBytes := SplittedArboStrToBytes(strParts[0], strParts[1], true, true)
 	// Hash the original input to compare with reconstructed bytes
 	expectedHash := sha256.Sum256(originalInput)
-
 	// Check if reconstructed bytes match the hash of the original input
 	qt.Assert(t, bytes.Equal(reconstructedBytes, expectedHash[:]), qt.IsTrue)
 }
diff --git a/vochain/transaction/proofs/zkproof/zkproof.go b/vochain/transaction/proofs/zkproof/zkproof.go
index 6bc1e468d..c70a3aa0c 100644
--- a/vochain/transaction/proofs/zkproof/zkproof.go
+++ b/vochain/transaction/proofs/zkproof/zkproof.go
@@ -3,12 +3,14 @@ package zkproof
 import (
 	"bytes"
 	"crypto/sha256"
+	"encoding/hex"
 	"fmt"
 	"math/big"
 
 	"go.vocdoni.io/dvote/crypto/zk"
 	"go.vocdoni.io/dvote/crypto/zk/circuit"
 	"go.vocdoni.io/dvote/crypto/zk/prover"
+	"go.vocdoni.io/dvote/log"
 	"go.vocdoni.io/dvote/vochain/state"
 	"go.vocdoni.io/proto/build/go/models"
 )
@@ -34,6 +36,10 @@ func (*ProofVerifierZk) Verify(process *models.Process, envelope *models.VoteEnv
 	}
 	hashedPid := sha256.Sum256(process.ProcessId)
 	if !bytes.Equal(hashedPid[:], proofProcessID) {
+		log.Warnw("process id mismatch",
+			"processID", fmt.Sprintf("%x", process.ProcessId),
+			"hashedPID", fmt.Sprintf("%x", hashedPid),
+			"proofPID", fmt.Sprintf("%x", proofProcessID))
 		return false, nil, fmt.Errorf("process id mismatch %x != %x", process.ProcessId, proofProcessID)
 	}
 	// verify the census root
@@ -45,12 +51,17 @@ func (*ProofVerifierZk) Verify(process *models.Process, envelope *models.VoteEnv
 		return false, nil, fmt.Errorf("census root mismatch")
 	}
 	// verify the votePackage hash
-	proofVoteHash, err := proof.VoteHash()
+	proofVoteHash, strParts, err := proof.VoteHash()
 	if err != nil {
 		return false, nil, fmt.Errorf("failed on parsing vote hash from public inputs provided: %w", err)
 	}
 	hashedVotePackage := sha256.Sum256(envelope.VotePackage)
 	if !bytes.Equal(hashedVotePackage[:], proofVoteHash) {
+		log.Warnw("voteHash id mismatch",
+			"votPackage", hex.EncodeToString(envelope.VotePackage),
+			"hashedVotePackage", hex.EncodeToString(hashedVotePackage[:]),
+			"proofParts", strParts,
+			"proofVotePackage", hex.EncodeToString(proofVoteHash))
 		return false, nil, fmt.Errorf("vote hash mismatch")
 	}
 	// get vote weight from proof publicSignals