NAS 5G AMF to UE 3GPP TS 24.501

5G NAS - Authentication Result

Authentication Result is the NAS message used to transport the final EAP authentication result from the network to the UE.

Message Fact Sheet

Protocol	nas	Network	5g
Spec	3GPP TS 24.501	Spec Section	8.2.3
Direction	AMF to UE	Message Type	5GMM signaling

Full message name	5G NAS - Authentication Result
Protocol	NAS
Technology	5G
Direction	AMF to UE
Interface	N1
Signaling bearer / channel	NAS signaling / Dedicated NAS message, commonly via DL Information Transfer
Typical trigger	Sent when the network must deliver EAP-based primary authentication result to the UE.
Main purpose	Carries the EAP success or failure result in EAP-based primary authentication.
Main specification	3GPP TS 24.501, 8.2.3
Release added	Release 15
Procedures where used	5G Authentication Procedure, 5G Initial Registration

What is Authentication Result in simple terms?

Authentication Result is the NAS message used to transport the final EAP authentication result from the network to the UE.

Carries the EAP success or failure result in EAP-based primary authentication.

Why this message matters

Authentication Result tells the UE the final EAP-based authentication outcome.

Where this message appears in the call flow

5G Authentication Procedure

Call flow position: Network result message in the EAP-based authentication branch.

Typical state: UE has already answered an EAP-based authentication request.

Preconditions:

The procedure is using EAP-based primary authentication.

Next likely message: Security Mode Command, Registration continuation, or termination depending on result

Call flow position

Previous message(s): Authentication Response

Next message(s): Security Mode Command, Registration Accept, Procedure termination

Message direction and transport

Sender and receiver: AMF to UE

Interface: N1

Domain: Core-side mobility management signaling for EAP-based authentication result transport

Signaling bearer: NAS signaling

Logical channel: Dedicated NAS message, commonly via DL Information Transfer

Transport / encapsulation: NAS 5GS message carried end-to-end between AMF and UE

Security context: Used in the EAP-based authentication branch; protection depends on the exact procedure stage.

Message Structure Overview

Authentication Result is mainly relevant for EAP-based primary authentication, not for every ordinary 5G AKA path.

ASN.1 Message Syntax for 5G NAS - Authentication Result

This message is not typically analyzed as ASN.1 on the wire. It is usually read as a NAS or protocol field structure instead.

Authentication Result is a NAS 24.501 message, not an ASN.1 message.

5G NAS - Authentication Result - Example Dump

Authentication Result
  Extended Protocol Discriminator: 5G Mobility Management
  Security Header Type: Plain NAS
  Message Type: Authentication Result
  ngKSI: 3
  EAP Message: Success

How to read this dump

Check whether the procedure is actually EAP-based before expecting this message in the trace.

Important Information Elements

IE	Required	Description
`ngKSI`	Yes	Identifies the NAS key set context selected with the EAP result.
`EAP message`	Yes	Carries the EAP success or EAP failure message delivered to the UE.

Detailed field explanation

`ngKSI`

Identifies the NAS key set context selected with the EAP result.

Presence: Required

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

`EAP message`

Carries the EAP success or EAP failure message delivered to the UE.

Presence: Required

In practice: If present, it reflects the external DN authentication result. It is worth checking when the session succeeds on NAS but service access still depends on an external authentication flow.

What to check in logs and traces

Confirm the authentication branch uses EAP and not pure 5G AKA-only result handling.
Inspect the EAP message result carefully.
Correlate the result with the next Security Mode or registration step.

Common Issues and Troubleshooting

Authentication seems to succeed but no normal registration continuation follows.

Likely cause: The EAP result may indicate failure or the next NAS step may not have been triggered correctly.

What to inspect: Check the EAP result contents and the next AMF action.

Next step: Verify whether the registration path continues into Security Mode Command or terminates.

FAQ

Is Authentication Result always present in 5G?

No. It is mainly associated with EAP-based authentication result delivery rather than every basic 5G AKA flow.

Related message pages

Related Procedures

Related Tools

Use This Reference in Practice

Decode this message with the 3GPP Decoder, inspect the related message database, or open the matching call flow to see where this signaling step fits in the full procedure.