5G • Security
K_NASint
NAS Integrity Protection Key
Integrity protection key used by UE and AMF to compute 32-bit Message Authentication Codes (MAC) on NAS PDUs.
Technical Explanation
Derived from K_AMF, K_NASint is used with the selected NIA algorithm (128-NIA1, 128-NIA2, 128-NIA3) to calculate a Message Authentication Code (MAC-I). This guarantees that NAS signaling cannot be tampered with or replayed by rogue base stations or man-in-the-middle attackers.
Key Functions
- Guarantees authenticity and anti-tampering of all NAS messages
- Computes 32-bit Message Authentication Code (MAC-I) on every NAS PDU
- Mandatory on all 5G NAS messages after security activation
Specifications
3GPP TS 33.501
Interfaces
N1
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