DECRYPTING A NAS MESSAGE TRACED TO AN E-UTRAN

1 . A method for decrypting a Non-Access Stratum (NAS) message traced in an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), the method comprising the steps of:

providing security information for a trace record of the NAS message; and

decrypting the NAS message using the security information.

2 . The method of claim 1 , wherein the security information includes input parameters for decrypting the NAS message.

3 . The method of claim 1 , wherein the decrypting step is performed in a Mobility Management Entity under the request from E-UTRAN.

4 . The method of claim 1 , wherein the providing step is performed in a Mobility Management Entity, and the decrypting step is performed in a Trace Collection Entity.

5 . The method of claim 1 , wherein the providing step includes adding the security information for a trace record for a cell traffic trace.

6 . The method of claim 1 , wherein the providing step includes adding the security information for a management activated trace from E-UTRAN.

7 . The method of claim 1 , wherein the providing step includes adding the security information for a signalling activated trace.

8 . The method of claim 1 , further comprising the step of tracing the decrypted NAS message, comprising the substeps of:

requesting to record the decrypted NAS message;

recording the decrypted NAS message into trace record;

requesting to stop recording the NAS message; and

stopping recording the NAS message;

9 . The method of claim 8 , wherein the requesting to record and requesting to stop recording steps are performed in an E-UTRAN eNodeB, and the recording and stopping recording steps are performed in a Mobility Management Entity.

10 . The method of claim 8 , wherein the tracing step includes cell traffic tracing.

11 . A method for decrypting a Non-Access Stratum (NAS) message traced in an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), the method comprising the steps of:

providing security information along with a trace record of the NAS message by a Mobility Management Entity; and

decrypting the NAS message using the security information in a Trace Collection Entity.

12 . The method of claim 11 , wherein the providing step includes the substeps of:

requesting a trace session activation;

starting a trace session;

starting a trace recording session;

forwarding cell traffic trace information; and

adding a user equipment identifier for each trace record, including the security information of NAS messages in each trace record, and including a trace recording session reference.

13 . The method of claim 11 , wherein the identifier of the adding step is an International Mobile Subscriber Identifier or International Mobile Equipment Identifier and Software Version Number IMSI/IMEI(SV).

14 . The method of claim 11 , wherein the providing step includes the substeps of:

requesting a trace session activation;

forwarding a trace session activation request including the user equipment identifier;

starting a trace session;

receiving a triggering event to activate a trace record;

starting a trace recording session including the security information of NAS messages in each trace record;

sending a message to activate a trace session; and

starting the trace session and a trace recording session for the identifier.

15 . The method of claim 11 , wherein the providing step includes the substeps of:

requesting a trace session activation;

starting a trace session;

receiving a triggering event to activate a trace record;

starting a trace recording session including the security information of NAS messages in each trace record;

sending a message to activate a trace session; and

starting the trace session and a trace recording session.

16 . A system for decrypting a Non-Access Stratum (NAS) message traced in an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), the system comprising:

a Mobility Management Entity operable to provide security information with a trace record of the NAS message; and

a Trace Collection Entity operable to decrypt the NAS message using the security information.