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Use zero padding for EF['ACC'] field 

The ``EF_ACC`` field defines the access control class (ACC)
for a subscriber.

Without this patch, the implementation adds padding 1 towards
the most significant bits if the input is shorter than 2 bytes.

However, it should be padded with 0, otherwise additional ACCs
are allocated to the subscriber. (Probably only a single bit
shall be set to 1)

Excerpt from [ETSI TS 131 102, 4.2.15](https://www.etsi.org/deliver/etsi_ts/131100_131199/131102/04.15.00_60/ts_131102v041500p.pdf):

```
EF_ACC: Two bytes: B1, B2

B1.b8...B1.b4: high priority users (class 15...11)
B1.b3: always 0
B1.b2...B1.b2 and B2.b7...B2.b0: normal priority users (class 9...0) - to be evenly distributed across subscribers
```

**Legend:** Byte X, bit Y: BX.bY


Change-Id: I1b8dc01a6c48adad1ed8158de59b12519ed688e9
This commit is contained in:
Robert Falkenberg 2021-04-01 16:14:27 +02:00 committed by laforge
parent c98ef8a79d
commit 75487aed90
1 changed files with 1 additions and 1 deletions
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2
pySim/cards.py
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@ -76,7 +76,7 @@ class Card(object):
return sw
def update_acc(self, acc):
data, sw = self._scc.update_binary(EF['ACC'], lpad(acc, 4))
data, sw = self._scc.update_binary(EF['ACC'], lpad(acc, 4, c='0'))
return sw
def read_hplmn_act(self):