5G • Security

K_NASenc

NAS Encryption Key

128-bit or 256-bit symmetric ciphering key protecting Non-Access Stratum signaling across the N1 interface.

Technical Explanation

K_NASenc is derived by the UE and AMF from K_AMF using a KDF with the selected 5G encryption algorithm ID (NEA0, 128-NEA1, 128-NEA2, 128-NEA3). It encrypts all sensitive NAS messages (registration, identity, PDU session requests) between UE and AMF.

Key Functions

  • Encrypts NAS signaling messages over the N1 interface
  • Protects user privacy and session requests from over-the-air eavesdropping
  • Supports 128-bit and 256-bit AES, SNOW 3G, and ZUC algorithms
Specifications
3GPP TS 33.501
Interfaces
N1

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