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SJA5: Proper encode/decode of TUAK data in EF.USIM_AUTH_KEY 

Unfortunately, TUAK requires a number of additional (and
differently-sized) parameters, so the format of EF.USIM_AUTH_KEY
differs significantly depending on TUAK or non-TUAK case.

Change-Id: I0dcfe05777510fb34973dc2259b137133d8e199d
This commit is contained in:
Harald Welte 2023-05-29 21:07:24 +02:00 committed by laforge
parent 557c13685e
commit 03650582e0
1 changed files with 33 additions and 3 deletions
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36
pySim/sysmocom_sja2.py
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@ -183,13 +183,43 @@ class EF_USIM_SQN(TransparentEF):
class EF_USIM_AUTH_KEY(TransparentEF):
def __init__(self, fid='af20', name='EF.USIM_AUTH_KEY'):
super().__init__(fid, name=name, desc='USIM authentication key')
Algorithm = Enum(Nibble, milenage=4, sha1_aka=5, tuak=6, xor=15)
CfgByte = BitStruct(Padding(1), 'only_4bytes_res_in_3g'/Bit,
'use_sres_deriv_func_2_in_3g'/Bit,
'use_opc_instead_of_op'/Bit,
'algorithm'/Enum(Nibble, milenage=4, sha1_aka=5, tuak=6, xor=15))
'sres_deriv_func_2_in_3g'/Mapping(Bit, {1:0, 2:1}),
'use_opc_instead_of_op'/Mapping(Bit, {False:0, True:1}),
'algorithm'/Algorithm)
self._construct = Struct('cfg'/CfgByte,
'key'/HexAdapter(Bytes(16)),
'op_opc' /HexAdapter(Bytes(16)))
# TUAK has a rather different layout for the data, so we define a different
# construct below and use explicit _{decode,encode}_bin() methods for separating
# the TUAK and non-TUAK situation
CfgByteTuak = BitStruct(Padding(1),
'key_length'/Mapping(Bit, {128:0, 256:1}),
'sres_deriv_func_in_3g'/Mapping(Bit, {1:0, 2:1}),
'use_opc_instead_of_op'/Mapping(Bit, {False:0, True:1}),
'algorithm'/Algorithm)
TuakCfgByte = BitStruct(Padding(1),
'ck_and_ik_size'/Mapping(Bit, {128:0, 256:1}),
'mac_size'/Mapping(BitsInteger(3), {64:0, 128:1, 256:2}),
'res_size'/Mapping(BitsInteger(3), {32:0, 64:1, 128:2, 256:3}))
self._constr_tuak = Struct('cfg'/CfgByteTuak,
'tuak_cfg'/TuakCfgByte,
'num_of_keccak_iterations'/Int8ub,
'op_opc'/HexAdapter(Bytes(32)),
'k'/HexAdapter(Bytes(32)))
def _decode_bin(self, raw_bin_data: bytearray) -> dict:
if raw_bin_data[0] & 0x0F == 0x06:
return parse_construct(self._constr_tuak, raw_bin_data)
else:
return parse_construct(self._construct, raw_bin_data)
def _encode_bin(self, abstract_data: dict) -> bytearray:
if abstract_data['cfg']['algorithm'] == 'tuak':
return self._constr_tuak.build(abstract_data)
else:
return self._construct.build(abstract_data)
class EF_USIM_AUTH_KEY_2G(TransparentEF):