fix decimal to utf8 convertion and add error handling in convert even…

…t-data

internal/service/handlers/helpers/proof_params.go

@@ -8,7 +8,6 @@ import (
 	zk "github.com/rarimo/zkverifier-kit"
 	"github.com/status-im/keycard-go/hexutils"
 	"math/big"
-	"strconv"
 	"time"
 )
 
@@ -65,12 +64,12 @@ func Utf8ToHex(input string) string {
 }
 
 func DecimalToHexToUtf8(input string) (string, error) {
-	inputDecimal, err := strconv.Atoi(input)
-	if err != nil {
-		return "", fmt.Errorf("failde to convert input string to decimal: %w", err)
-
+	inputBig, ok := new(big.Int).SetString(input, 10)
+	if !ok {
+		return "", fmt.Errorf("failed to parse big int when converting to UTF8")
 	}
-	inputUtf8 := string(hexutils.HexToBytes(strconv.FormatInt(int64(inputDecimal), 16)))
+
+	inputUtf8 := string(inputBig.Bytes())
 
 	return inputUtf8, nil
 }

internal/service/handlers/verification_callback_light.go

@@ -59,7 +59,12 @@ func VerificationSignatureCallback(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	userIDHashDecimal, _ := new(big.Int).SetString(pubSignals[10], 10)
+	userIDHashDecimal, ok := new(big.Int).SetString(pubSignals[10], 10)
+	if !ok {
+		Log(r).Error("failed to parse event data")
+		ape.RenderErr(w, problems.BadRequest(err)...)
+		return
+	}
 	var eventDataBytes [32]byte
 	userIDHashDecimal.FillBytes(eventDataBytes[:])