diff --git a/test/go.mod b/test/go.mod
index a0008f31..53a9f956 100644
--- a/test/go.mod
+++ b/test/go.mod
@@ -20,7 +20,7 @@ require (
 	github.com/free5gc/smf v0.0.0
 	github.com/free5gc/udm v0.0.0
 	github.com/free5gc/udr v0.0.0
-	github.com/free5gc/util v1.0.5-0.20230511064842-2e120956883b
+	github.com/free5gc/util v1.0.5-0.20230823103219-e511c4fd20ef
 	github.com/gin-gonic/gin v1.9.0
 	github.com/go-ping/ping v0.0.0-20210506233800-ff8be3320020
 	github.com/google/uuid v1.3.0
diff --git a/test/go.sum b/test/go.sum
index 4f53256c..d6c47e4d 100644
--- a/test/go.sum
+++ b/test/go.sum
@@ -100,8 +100,9 @@ github.com/free5gc/pfcp v1.0.6/go.mod h1:WzpW7Zxhx5WONMumNKRWbPn7pl/iTYp2FqRLNiO
 github.com/free5gc/tlv v1.0.2-0.20230131124215-8b6ebd69bf93 h1:QPSSI5zw4goiIfxem9doVyMqTO8iKLQ536pzpET5Y+Q=
 github.com/free5gc/tlv v1.0.2-0.20230131124215-8b6ebd69bf93/go.mod h1:KbbQJIgGaA2jIwnTJgJ/lE3JSDEp3898S6c4TEq0Vyg=
 github.com/free5gc/util v1.0.5-0.20230306071612-a52909216bd2/go.mod h1:fgV0hXf5arxAWs8D9LfrrfNByZ1IDCWYlgBzncy5GtE=
-github.com/free5gc/util v1.0.5-0.20230511064842-2e120956883b h1:XMw3j+4AEXLeL/uyiZ7/qYE1X7Ul05RTwWBhzxCLi+0=
 github.com/free5gc/util v1.0.5-0.20230511064842-2e120956883b/go.mod h1:l2Jrml4vojDomW5jdDJhIS60KdbrE9uPYhyAq/7OnF4=
+github.com/free5gc/util v1.0.5-0.20230823103219-e511c4fd20ef h1:ne0EMnst7wbLoaY2Uvn/2Kvp/KkXKMQJcaIJQKFe+a4=
+github.com/free5gc/util v1.0.5-0.20230823103219-e511c4fd20ef/go.mod h1:l2Jrml4vojDomW5jdDJhIS60KdbrE9uPYhyAq/7OnF4=
 github.com/gin-contrib/cors v1.3.1 h1:doAsuITavI4IOcd0Y19U4B+O0dNWihRyX//nn4sEmgA=
 github.com/gin-contrib/cors v1.3.1/go.mod h1:jjEJ4268OPZUcU7k9Pm653S7lXUGcqMADzFA61xsmDk=
 github.com/gin-contrib/sse v0.1.0 h1:Y/yl/+YNO8GZSjAhjMsSuLt29uWRFHdHYUb5lYOV9qE=
diff --git a/test/registration_test.go b/test/registration_test.go
index eeb1c29c..b51b24fe 100644
--- a/test/registration_test.go
+++ b/test/registration_test.go
@@ -641,7 +641,7 @@ func TestServiceRequest(t *testing.T) {
 
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
@@ -1199,7 +1199,7 @@ func TestPDUSessionReleaseRequest(t *testing.T) {
 
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
@@ -1412,7 +1412,7 @@ func TestPDUSessionReleaseAbnormal(t *testing.T) {
 
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
@@ -1663,7 +1663,7 @@ func TestXnHandover(t *testing.T) {
 
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
@@ -1861,7 +1861,7 @@ func TestPaging(t *testing.T) {
 	// send PduSessionEstablishmentRequest Msg
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
@@ -2143,7 +2143,7 @@ func TestN2Handover(t *testing.T) {
 	// send PduSessionEstablishmentRequest Msg
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
@@ -2481,7 +2481,7 @@ func TestDuplicateRegistration(t *testing.T) {
 
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
@@ -2751,7 +2751,7 @@ func TestAFInfluenceOnTrafficRouting(t *testing.T) {
 	// send GetPduSessionEstablishmentRequest Msg
 
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet",
-		&models.Snssai{Sst: 1, Sd: "010203"})
+		&models.Snssai{Sst: 1, Sd: "fedcba"})
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
 	assert.Nil(t, err)
 	sendMsg, err = test.GetUplinkNASTransport(ue.AmfUeNgapId, ue.RanUeNgapId, pdu)
@@ -3037,7 +3037,7 @@ func TestReSynchronization(t *testing.T) {
 
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
@@ -3276,7 +3276,7 @@ func TestRequestTwoPDUSessions(t *testing.T) {
 
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)
@@ -3612,7 +3612,7 @@ func TestEAPAKAPrimeAuthentication(t *testing.T) {
 
 	sNssai := models.Snssai{
 		Sst: 1,
-		Sd:  "010203",
+		Sd:  "fedcba",
 	}
 	pdu = nasTestpacket.GetUlNasTransport_PduSessionEstablishmentRequest(10, nasMessage.ULNASTransportRequestTypeInitialRequest, "internet", &sNssai)
 	pdu, err = test.EncodeNasPduWithSecurity(ue, pdu, nas.SecurityHeaderTypeIntegrityProtectedAndCiphered, true, false)