N32-c vs N32-f
The N32 interface between two SEPPs is split into two sub-interfaces. N32-c handles the control-plane handshake — cipher suites, security capabilities, key material. N32-f carries the actual service-based signaling.
| Attribute | N32-c | N32-f |
|---|---|---|
| Role | Handshake, capability exchange | Forwarding of NF service messages |
| Transport | TLS 1.2/1.3 | TLS or PRINS (JOSE) |
| Frequency | Session establishment | Every SBA message across PLMN |
| IE-level protection | Not applicable | JWE-encrypted sensitive IEs |
| IPX visibility | None | Modification via signed schema (PRINS) |
Verdict
N32-c is the setup; N32-f is where every roaming signaling message flows. Deployments that enable TLS on N32-f but skip PRINS gain transport encryption but leave SUPI and key material visible to any IPX in the middle.