remove text replaced by specification
diff --git a/README.md b/README.md
index edbde8a..da98b0d 100644
--- a/README.md
+++ b/README.md
@@ -5,146 +5,4 @@
Homepage: https://osmocom.org/projects/imsi-pseudo/wiki
-## How it works
-
-The first pseudo IMSI gets allocated in the HLR, as the SIM card is
-provisioned. After that pseudo IMSI is used for the first time in location
-update, the HLR waits for some time, then decides the next pseudo IMSI and
-sends it together with a delay value as SMS to the SIM. The SIM applet receives
-the SMS and waits the specified delay. Then it overwrites its current IMSI with
-the new one, marks the TMSI as invalid, and initiates the next location update.
-Afterwards, the process repeats.
-
-```
-HLR <-> SIM LOCATION UPDATE, imsi_pseudo=200
-(time passes)
-HLR -> SIM NEW PSEUDO IMSI, imsi_pseudo=123, delay=60
-(time passes until the SMS arrives)
-(SIM applet waits 60 seconds)
-HLR <-> SIM LOCATION UPDATE, imsi_pseudo=123
-...
-```
-
-## In detail
-
-### 1. Provisioning the SIM
-
-The HLR allocates a new pseudo IMSI as random choice from the pool of available
-IMSIs. The pseudo IMSI must not be used by any other subscriber as pseudo IMSI,
-but may be the real IMSI of another subscriber. The subscriber-specific counter
-imsi_pseudo_i is 0 for the first allocated IMSI for that subscriber.
-
-| id | imsi | imsi_pseudo | imsi_pseudo_i |
-|------|--------|---------------|---------------|
-| 1 | 100 | 200 | 0 |
-
-The pseudo IMSI is saved to the SIM as IMSI, instead of the real IMSI. The SIM
-is also provisioned with the IMSI pseudonymization applet.
-
-### 2. Successful Location Update with pseudo IMSI
-
-a) If this was the first Location Update after provisioning the SIM, the
-subscriber has only one pseudo IMSI allocated. The HLR waits for some time.
-Then it allocates the next pseudo IMSI from the pool of available IMSIs (as in
-1., but with imsi_pseudo_i increased by one). The HLR sends the new
-pseudo IMSI, the imsi_pseudo_i and a random delay value in one SMS to the SIM.
-
-The random delay is how long the SIM applet should wait before changing the
-IMSI. This delay prevents easy correlation of the arrival of the SMS with the
-Location Update that will follow in 3. by the SIM. Due to other latencies in
-the network, this is a minimum delay. At this point, the subscriber has two
-allocated pseudo IMSIs:
-
-| id | imsi | imsi_pseudo | imsi_pseudo_i |
-|------|--------|---------------|---------------|
-| 1 | 100 | 200 | 0 |
-| 2 | 100 | 123 | 1 |
-
-b) If this was not the first Location Update after provisioning a new SIM, the
-subscriber already has two pseudo IMSIs allocated when doing the Location
-Update. The HLR compares imsi_pseudo_i to find out if the Location Update was
-done with the newer or older pseudo IMSI.
-
-If the older pseudo IMSI was used, then the SIM applet was not able to set the
-new IMSI. This may be caused by an SMS arriving late, possibly even months
-after it was sent in case the UE was without power for a long period of time.
-Therefore the HLR cannot deallocate the newer pseudo IMSI without risking that
-the SIM would configure that IMSI and then be locked out (unable to do any
-further location updates). Instead, the HLR proceeds like in a), but sends the
-same unused new pseudo IMSI again instead of allocating a new one.
-
-If the newer pseudo IMSI was used, the SIM applet has successfully set the new
-IMSI. The HLR deallocates the old pseudo IMSI and sends a Purge MS request to
-the VLR with the old pseudo IMSI. Then the HLR proceeds like in a).
-
-### 3. Arrival of the SMS
-
-The SIM applet verifies, that imsi_pseudo_i is higher than the last
-imsi_pseudo_i it has seen (initially: 0). If that is not the case, it discards
-the message.
-
-The SIM applet registers a timer to wait the specified delay. When the timer
-expires, the applet updates the last imsi_pseudo_i value that it has seen. Then
-it overwrites the IMSI with the next pseudo IMSI and invalidates the TMSI and
-Kc. The applet triggers a refresh, which causes the SIM to do a new Location
-Update with the new IMSI.
-
-It is important, that the SIM does not invoke the IMSI detach procedure (TS
-04.08 Section 4.3.4). This is controlled by the network. Otherwise it becomes
-trivial to correlate the detach of the old IMSI with the attach or Location
-Update of the new IMSI.
-
-## Notes
-
-### What if the SMS gets lost?
-
-Both the old and the new pseudo IMSI entry exist in the HLR.
-
-The SIM will use the old pseudo IMSI in the next Location Update. The HLR will
-try to send _the same_ new pseudo IMSI with the same new imsi_pseudo_i, as soon
-as the next Location Update is complete.
-
-### What if the SMS arrives late?
-
-The imsi_pseudo_i counter will not be higher than the value the SIM applet
-already knows. Therefore, the applet will discard the message.
-
-### Warning the user if SMS don't arrive
-
-An attacker could possibly block the SMS from arriving at the SIM applet. In
-that case, the SIM would continue using the old pseudo IMSI indefinitely.
-
-We can count the location updates done with the same pseudo IMSI in the SIM
-applet, and warn the user if the same pseudo IMSI has been used more than N
-(e.g. 5) times.
-
-### End2end encryption
-
-When deploying the IMSI pseudonymization, the operator should make sure that
-the pseudo IMSI related SMS between the HLR and the SIM cannot be read or
-modified by third parties. Otherwise, the next pseudonymous IMSI is leaked, and
-in case of modifying the IMSI in the SMS, the SIM may be locked out of the
-network.
-
-OTA SMS are usually encrypted and authenticated (TS 03.48), with algorithms and
-key lengths that the operator chooses (depending on the SIM and how it is
-configured).
-
-It was considered to add an additional layer of end2end encryption for the
-pseudonymized IMSIs on top, but this is out-of-scope for this project. For
-reference, one could pre-provision a random "imsi_pseudo_key" with the SIM
-card, store it in the pseudo IMSI table in the HLR, and deploy a new encryption
-key together with each new pseudo IMSI, attached to the SMS.
-
-### User-configurable minimum duration between IMSI changes
-
-It may be desirable to let users configure their minimum duration between IMSI
-changes. This allows people with a high privacy requirement to switch their
-pseudonymous IMSI more often, and it allows the IMSI change to happen less
-often if it is distracting to the user. The latter depends on the phone's
-software, for example:
-* 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.
+Find the specification in the docs subdir.
diff --git a/docs/specification.md b/docs/specification.md
deleted file mode 100644
index 13a221a..0000000
--- a/docs/specification.md
+++ /dev/null
@@ -1,28 +0,0 @@
-# [WIP] Make IMSI Pseudonymization an optional extension of 3GPP TS
-
-NOTE: this file is deprecated, it will be replaced by imsi-pseudo-spec.adoc.
-
-Relevant specs:
-* 3GPP TS 23.008: Organization of subscriber data
- * Add pseudo IMSI and pseudo_imsi_i optionally to be saved in the HLR
-* "Process Update_Location_HLR" of TS 09.02
- * Cancel location in old VLR/SGSN if IMSI pseudonymization is enabled, and a
- previous pseudonymous IMSI exists for the subscriber
-
-Optional additions we need to make, and where to make them:
-
-* Initial provisioning of the SIM: can optionally have a pseudo IMSI
-* During location update, the HLR uses the pseudo IMSI for all communication
- with the VLR / MSC
- * Is there anything to update? We just replace the IMSI, so the SIM and the
- VLR / MSC don't act any different
-* After successful location update:
- * See 2. in README.md
-
-TODO:
-* extend the list above with the exact sections of the spec, where the new
- information should be placed
-* Is there a spec for SIM applets, or do we put the SIM applet behaviour in the
- regular spec for SIM cards, or mention its behavior in the location update
- related change?
-* describe everything in detail, fill in the full contents for the SMS etc.