Revision 64d154ce
Added by osmith about 4 years ago
| docs/imsi-pseudo-spec.adoc | ||
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<<< |
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== Required Changes |
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[[hlr-imsi-pseudo-storage]] |
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=== Pseudonymous IMSI Storage in the HLR |
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The HLR must store up to two pseudonymous IMSIs (imsi_pseudo) and their related |
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=== Process Update_Location_HLR |
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All IMSI Pseudonymization related changes to Process Update_Location_HLR |
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(3GPP TS 29.002) are optional. All deviations from the existing specification
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that are outlined in this section are expected to be enabled or disabled
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entirely where IMSI pseudonymization is implemented.
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(3GPP TS 29.002) are optional. Deviations from the existing specification that
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are outlined in this section are expected to be enabled or disabled entirely
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where IMSI pseudonymization is implemented. |
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[[figure-imsi-pseudo]] |
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.Process Update_Location_HLR with IMSI pseudonymization changes |
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MSC => HLR [label="Update Location Request"]; |
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--- [label="If new pseudonymous IMSI was used: deallocate and cancel old pseudonymous IMSI"]; |
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HLR box HLR [label="Deallocate old pseudonymous IMSI"];
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HLR box HLR [label="Deallocate old pseudonymous IMSI"];
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MSC <= HLR [label="Cancel Location Request"]; |
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MSC => HLR [label="Cancel Location Result"]; |
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---; |
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MSC <= HLR [label="Insert Subscriber Data Request"]; |
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MSC => HLR [label="Insert Subscriber Data Result"]; |
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HLR box HLR [label="Start Next_Pseudo_IMSI_Timer"];
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HLR box HLR [label="Start Next_Pseudo_IMSI_Timer"];
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MSC <= HLR [label="Update Location Result"]; |
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MSC box MSC [label="Finish Location Updating with ME"],
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MSC box MSC [label="Finish Location Updating with ME"],
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HLR box HLR [label="Wait for Next_Pseudo_IMSI_Timer expiry"];
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HLR box HLR [label="Wait for Next_Pseudo_IMSI_Timer expiry"];
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|||; |
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...; |
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HLR box HLR [label="Next_Pseudo_IMSI_Timer expired"];
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HLR box HLR [label="Next_Pseudo_IMSI_Timer expired"];
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HLR box HLR [label="\nAllocate new pseudonymous IMSI\nif subscriber only has one allocated\n"];
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HLR box HLR [label="\nAllocate new pseudonymous IMSI\nif subscriber has only one allocated\n"];
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SMSC <= HLR [label="Next Pseudonymous IMSI SMS"]; |
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SMSC box SMSC [label="Deliver SMS to ME"]; |
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} |
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---- |
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==== Update Location Request |
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When Update Location Request arrives, the HLR does not look up the subscriber |
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by the IMSI, but by the pseudonymous IMSI instead. Unless the subscriber has |
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two pseudonymous IMSI allocated and used the old pseudonymous IMSI in the |
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==== Insert Subscriber Data Result |
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ISD works like before, then set Next_Pseudo_IMSI_Timer |
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When Insert Subscriber Data Result arrives, a subscriber specific |
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Next_Pseudo_IMSI_Timer starts. |
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==== Next_Pseudo_IMSI_Timer Expires |
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* if subscriber has only one pseudo IMSI: |
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* abort if not enough IMSIs available |
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* generate new pseudo IMSI as described earlier |
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* set imsi_pseudo_i like last one + 1 |
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* send SMS to subscriber's SIM with newer pseudo IMSI |
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If the subscriber has only one pseudonymous IMSI allocated, and the amount of |
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available IMSIs in the HLR is high enough, a second pseudonymous IMSI and |
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related imsi_pseudo_i gets allocated for the subscriber (as described in |
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<<hlr-imsi-pseudo-storage>>). |
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If the subscriber still has only one pseudonymous IMSI, because not enough |
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IMSIs were available in the HLR, the process is aborted here and no SMS with |
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a next pseudonymous IMSI is sent to the subscriber. The subscriber will get a |
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new pseudonymous IMSI during the next Location Updating Procedure, if the HLR |
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has enough IMSIs available at that point. |
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An SMS is sent to the SMS - Service Centre (SMS-SC) with the newer pseudonymous |
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IMSI (higher imsi_pseudo_i, see <<hlr-imsi-pseudo-i>>) and related |
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imsi_pseudo_i value. |
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[[sms-format]] |
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==== SMS Format |
Also available in: Unified diff
spec: next pseudo_imsi_timer expires