From a0354de49a6d3da7c39bc5b1df93b4b7d239719f Mon Sep 17 00:00:00 2001 From: Oliver Smith Date: Thu, 9 Apr 2020 15:13:38 +0200 Subject: [PATCH] spec: User-configurable Minimum Duration Between IMSI Changes --- docs/imsi-pseudo-spec.adoc | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/docs/imsi-pseudo-spec.adoc b/docs/imsi-pseudo-spec.adoc index eaacd0c..90fec9b 100644 --- a/docs/imsi-pseudo-spec.adoc +++ b/docs/imsi-pseudo-spec.adoc @@ -325,10 +325,6 @@ imsi_pseudo_i value. [[sms-structure]] ==== Next Pseudonymous IMSI SMS Structure -// FIXME -IMPORTANT: This is a draft. The structure is likely to change after the -reference implementation phase. - .Next pseudonymous IMSI SMS structure [packetdiag] ---- @@ -342,6 +338,10 @@ reference implementation phase. } ---- +// FIXME +IMPORTANT: This is a draft. The structure is likely to change after the +reference implementation phase. + IMSI_PSEUDO_I: 32 bits:: See <>. @@ -422,5 +422,21 @@ specification, but found to be out of scope. === User-configurable Minimum Duration Between IMSI Changes +It may be desirable to let subscribers configure their minimum duration between +IMSI changes. This allows subscribers with a high privacy requirement to switch +their pseudonymous IMSI more often, and it allows the pseudonymous IMSI change +to happen less frequently if it is distracting to the subscriber. + +How distracting the pseudonymous IMSI change is, depends on the ME. The +following examples were observed: + +// FIXME: might need an update after SYS#4481 + +* A Samsung GT-I9100 Galaxy SII smartphone with Android 4.0.3 displays a + message at the bottom of the screen for about 5 seconds, but the user + interface remains usable. +* A Samsung GT-E1200 feature phone displays a waiting screen for 16 to 17 + seconds and is unusable during that time. + <<< include::./common/chapters/gfdl.adoc[]