3GPP 24.501 v20.0.0 — the document's own text
8.2.1.1 Message definition
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
The AUTHENTICATION REQUEST message is sent by the AMF to the UE to initiate authentication of the UE identity. See table 8.2.1.1.1.
Message type: AUTHENTICATION REQUEST
Significance: dual
Direction: network to UE
Table 8.2.1.1.1: AUTHENTICATION REQUEST message content
| IEI | Information Element | Type/Reference | Presence | Format | Length |
|---|---|---|---|---|---|
| Extended protocol discriminator | Extended protocol discriminator9.2 | M | V | 1 | |
| Security header type | Security header type9.3 | M | V | 1/2 | |
| Spare half octet | Spare half octet9.5 | M | V | 1/2 | |
| Authentication request message identity | Message type9.7 | M | V | 1 | |
| ngKSI | NAS key set identifier9.11.3.32 | M | V | 1/2 | |
| Spare half octet | Spare half octet9.5 | M | V | 1/2 | |
| ABBA | ABBA9.11.3.10 | M | LV | 3-n | |
| 21 | Authentication parameter RAND (5G authentication challenge) | Authentication parameter RAND9.11.3.16 | O | TV | 17 |
| 20 | Authentication parameter AUTN (5G authentication challenge) | Authentication parameter AUTN9.11.3.15 | O | TLV | 18 |
| 78 | EAP message | EAP message9.11.2.2 | O | TLV-E | 7-1503 |