diff --git a/api.go b/api.go
index ec80501..6f2999a 100644
--- a/api.go
+++ b/api.go
@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"math/rand"
 	"net/url"
 	"os"
@@ -57,7 +56,7 @@ type HARData struct {
 }
 
 func readHAR() {
-	file, err := ioutil.ReadFile("chatgpt.har")
+	file, err := os.ReadFile("chatgpt.har")
 	if err != nil {
 		fmt.Println(err)
 		return
@@ -88,7 +87,7 @@ func readHAR() {
 	arkHeader = make(http.Header)
 	for _, h := range arkReq.Request.Headers {
 		// arkHeader except cookie & content-length
-		if strings.EqualFold(h.Name, "content-length") == false && strings.EqualFold(h.Name, "cookie") == false && strings.HasPrefix(h.Name, ":") == false {
+		if !strings.EqualFold(h.Name, "content-length") && !strings.EqualFold(h.Name, "cookie") && !strings.HasPrefix(h.Name, ":") {
 			arkHeader.Set(h.Name, h.Value)
 			if strings.EqualFold(h.Name, "user-agent") {
 				bv = h.Value
diff --git a/crypt.go b/crypt.go
index 405c4b0..dc85d5f 100644
--- a/crypt.go
+++ b/crypt.go
@@ -135,6 +135,9 @@ func Decrypt(data string, key string) string {
 
 func AesDecrypt(baseText string, password string) (string, error) {
 	encBytes, err := base64.StdEncoding.DecodeString(baseText)
+	if err != nil {
+		return "", err
+	}
 	var encData encryptionData
 	err = json.Unmarshal(encBytes, &encData)
 	if err != nil {
@@ -145,6 +148,9 @@ func AesDecrypt(baseText string, password string) (string, error) {
 		return "", err
 	}
 	salt, err := hex.DecodeString(encData.S)
+	if err != nil {
+		return "", err
+	}
 	key, iv, err := DefaultEvpKDF([]byte(password), salt)
 	if err != nil {
 		return "", err
diff --git a/util.go b/util.go
index db70c67..45b3ed0 100644
--- a/util.go
+++ b/util.go
@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"math/rand"
 	"net/url"
 	"os"
 	"strings"
@@ -74,12 +73,3 @@ func getRequestId(sessionId string) string {
 	pwd := fmt.Sprintf("REQUESTED%sID", sessionId)
 	return Encrypt(`{"sc":[147,307]}`, pwd)
 }
-
-func randomHex(length int) string {
-	chars := []rune("0123456789abcdef")
-	var b strings.Builder
-	for i := 0; i < length; i++ {
-		b.WriteRune(chars[rand.Intn(len(chars))])
-	}
-	return b.String()
-}