diff --git a/php/src/Kernel/Util/AntCertificationUtil.php b/php/src/Kernel/Util/AntCertificationUtil.php
index 8d69d19..177ccb1 100644
--- a/php/src/Kernel/Util/AntCertificationUtil.php
+++ b/php/src/Kernel/Util/AntCertificationUtil.php
@@ -48,7 +48,7 @@ public function getRootCertSN($certPath)
         for ($i = 0; $i < count($array) - 1; $i++) {
             $ssl[$i] = openssl_x509_parse($array[$i] . "-----END CERTIFICATE-----");
             if (strpos($ssl[$i]['serialNumber'], '0x') === 0) {
-                $ssl[$i]['serialNumber'] = $this->hex2dec($ssl[$i]['serialNumber']);
+                $ssl[$i]['serialNumber'] = $this->hex2dec($ssl[$i]['serialNumberHex']);
             }
             if ($ssl[$i]['signatureTypeLN'] == "sha1WithRSAEncryption" || $ssl[$i]['signatureTypeLN'] == "sha256WithRSAEncryption") {
                 if ($SN == null) {
@@ -72,7 +72,7 @@ function hex2dec($hex)
     {
         $dec = 0;
         $len = strlen($hex);
-        for ($i = (false === strpos(strtolower($hex), '0x') ? 1 : 3); $i <= $len; $i++) {
+        for ($i = 1; $i <= $len; $i++) {
             $dec = bcadd($dec, bcmul(strval(hexdec($hex[$i - 1])), bcpow('16', strval($len - $i))));
         }
         return $dec;
@@ -609,4 +609,4 @@ function stripSignerAsn($der = null)
         }
         return substr($der, 4, $len + 4);
     }
-}
+}
\ No newline at end of file