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AS Security Complete

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AS Security Complete is a signaling procedure in LTE (Long-Term Evolution) and 5G mobile networks that marks the successful completion of the authentication and security setup process between the User Equipment (UE) and the network's Authentication Server (AS). This procedure ensures the confidentiality and integrity of user data during communication. Below is a detailed technical explanation of the AS Security Complete procedure:

1. Authentication and Security Setup Preceding AS Security Complete:

  • Before AS Security Complete, several steps take place, including:
  • Authentication: The UE undergoes authentication to verify its identity and ensure it's authorized to access the network.
  • Key Agreement: The UE and the network establish cryptographic keys to secure the user's data and signaling.
  • Security Mode Command: The network sends a Security Mode Command message to the UE, instructing it to activate the agreed-upon security mechanisms.

2. UE Verification:

  • The UE performs the necessary cryptographic operations to verify the authenticity of the network. This involves using shared secrets, such as keys derived during the authentication process, to compute and compare message authentication codes (MACs) or integrity protection codes.

3. AS Security Complete Generation:

  • After successful verification of the network, the UE generates an AS Security Complete message, signaling that the authentication and security setup have been completed successfully.

4. Contents of AS Security Complete:

  • The AS Security Complete message typically includes the following information:
  • Integrity Protection: This message is typically integrity-protected to ensure its authenticity.
  • Message Authentication Code (MAC): A cryptographic code generated by the UE to prove the authenticity of the message.
  • Security Context: Information about the security parameters and keys that will be used for data encryption and integrity protection during subsequent communication.

5. Transmission to the Network:

  • The UE sends the AS Security Complete message to the network to inform it that the security setup is complete and that the UE is now ready for secure communication.

6. Network Verification:

  • The network verifies the authenticity and integrity of the received AS Security Complete message using the shared secrets and cryptographic algorithms agreed upon during the security setup.

7. Activation of Security Measures:

  • Upon successfully verifying the AS Security Complete message, the network activates the security measures for data encryption and integrity protection for the UE's communication sessions.

8. Secure Data Transfer:

  • With security now activated, data transfer between the UE and the network occurs securely, ensuring that user data remains confidential and protected from unauthorized access and tampering.

9. Procedure Completion:

  • The AS Security Complete procedure is considered complete when both the UE and the network have successfully verified the AS Security Complete message, and secure data transfer is established.

AS Security Complete is a critical step in establishing a secure communication session between the UE and the network. It ensures that data confidentiality and integrity are maintained, safeguarding user privacy and protecting against malicious attacks or eavesdropping during network communication.