aboutsummaryrefslogtreecommitdiffstats
path: root/pySim/utils.py
blob: 43e4c53562f7942ed2ee30ea6289be0051e72334 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
#!/usr/bin/env python
# -*- coding: utf-8 -*-

""" pySim: various utilities
"""

#
# Copyright (C) 2009-2010  Sylvain Munaut <tnt@246tNt.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#


def h2b(s):
	return ''.join([chr((int(x,16)<<4)+int(y,16)) for x,y in zip(s[0::2], s[1::2])])

def b2h(s):
	return ''.join(['%02x'%ord(x) for x in s])

def h2i(s):
	return [(int(x,16)<<4)+int(y,16) for x,y in zip(s[0::2], s[1::2])]

def i2h(s):
	return ''.join(['%02x'%(x) for x in s])

def h2s(s):
	return ''.join([chr((int(x,16)<<4)+int(y,16)) for x,y in zip(s[0::2], s[1::2])
						      if int(x + y, 16) != 0xff])

def s2h(s):
	return b2h(s)

# List of bytes to string
def i2s(s):
	return ''.join([chr(x) for x in s])

def swap_nibbles(s):
	return ''.join([x+y for x,y in zip(s[1::2], s[0::2])])

def rpad(s, l, c='f'):
	return s + c * (l - len(s))

def lpad(s, l, c='f'):
	return c * (l - len(s)) + s

def half_round_up(n):
	return (n + 1)//2

# IMSI encoded format:
# For IMSI 0123456789ABCDE:
#
# |     byte 1      | 2 upper | 2 lower  | 3 upper | 3 lower | ... | 9 upper | 9 lower |
# | length in bytes |    0    | odd/even |    2    |    1    | ... |    E    |    D    |
#
# If the IMSI is less than 15 characters, it should be padded with 'f' from the end.
#
# The length is the total number of bytes used to encoded the IMSI. This includes the odd/even
# parity bit. E.g. an IMSI of length 14 is 8 bytes long, not 7, as it uses bytes 2 to 9 to
# encode itself.
#
# Because of this, an odd length IMSI fits exactly into len(imsi) + 1 // 2 bytes, whereas an
# even length IMSI only uses half of the last byte.

def enc_imsi(imsi):
	"""Converts a string imsi into the value of the EF"""
	l = half_round_up(len(imsi) + 1)	# Required bytes - include space for odd/even indicator
	oe = len(imsi) & 1			# Odd (1) / Even (0)
	ei = '%02x' % l + swap_nibbles('%01x%s' % ((oe<<3)|1, rpad(imsi, 15)))
	return ei

def dec_imsi(ef):
	"""Converts an EF value to the imsi string representation"""
	if len(ef) < 4:
		return None
	l = int(ef[0:2], 16) * 2		# Length of the IMSI string
	l = l - 1						# Encoded length byte includes oe nibble
	swapped = swap_nibbles(ef[2:]).rstrip('f')
	if len(swapped) < 1:
		return None
	oe = (int(swapped[0])>>3) & 1	# Odd (1) / Even (0)
	if not oe:
		# if even, only half of last byte was used
		l = l-1
	if l != len(swapped) - 1:
		return None
	imsi = swapped[1:]
	return imsi

def dec_iccid(ef):
	return swap_nibbles(ef).strip('f')

def enc_iccid(iccid):
	return swap_nibbles(rpad(iccid, 20))

def enc_plmn(mcc, mnc):
	"""Converts integer MCC/MNC into 3 bytes for EF"""
	if len(mnc) == 2:
		mnc = "F%s" % mnc
	return swap_nibbles("%s%s" % (mcc, mnc))

def dec_spn(ef):
	byte1 = int(ef[0:2])
	hplmn_disp = (byte1&0x01 == 0x01)
	oplmn_disp = (byte1&0x02 == 0x02)
	name = h2s(ef[2:])
	return (name, hplmn_disp, oplmn_disp)

def enc_spn(name, hplmn_disp=False, oplmn_disp=False):
	byte1 = 0x00
	if hplmn_disp: byte1 = byte1|0x01
	if oplmn_disp: byte1 = byte1|0x02
	return i2h([byte1])+s2h(name)

def hexstr_to_fivebytearr(s):
	return [s[i:i+10] for i in range(0, len(s), 10) ]

def hexstr_to_threebytearr(s):
	return [s[i:i+6] for i in range(0, len(s), 6) ]

def hexstr_to_Nbytearr(s, nbytes):
	return [s[i:i+(nbytes*2)] for i in range(0, len(s), (nbytes*2)) ]

# Accepts hex string representing three bytes
def dec_mcc_from_plmn(plmn):
	ia = h2i(plmn)
	digit1 = ia[0] & 0x0F		# 1st byte, LSB
	digit2 = (ia[0] & 0xF0) >> 4	# 1st byte, MSB
	digit3 = ia[1] & 0x0F		# 2nd byte, LSB
	if digit3 == 0xF and digit2 == 0xF and digit1 == 0xF:
		return 0xFFF # 4095
	return derive_mcc(digit1, digit2, digit3)

def dec_mnc_from_plmn(plmn):
	ia = h2i(plmn)
	digit1 = ia[2] & 0x0F		# 3rd byte, LSB
	digit2 = (ia[2] & 0xF0) >> 4	# 3rd byte, MSB
	digit3 = (ia[1] & 0xF0) >> 4	# 2nd byte, MSB
	if digit3 == 0xF and digit2 == 0xF and digit1 == 0xF:
		return 0xFFF # 4095
	return derive_mnc(digit1, digit2, digit3)

def dec_act(twohexbytes):
	act_list = [
		{'bit': 15, 'name': "UTRAN"},
		{'bit': 14, 'name': "E-UTRAN"},
		{'bit':  7, 'name': "GSM"},
		{'bit':  6, 'name': "GSM COMPACT"},
		{'bit':  5, 'name': "cdma2000 HRPD"},
		{'bit':  4, 'name': "cdma2000 1xRTT"},
	]
	ia = h2i(twohexbytes)
	u16t = (ia[0] << 8)|ia[1]
	sel = []
	for a in act_list:
		if u16t & (1 << a['bit']):
			sel.append(a['name'])
	return sel

def dec_xplmn_w_act(fivehexbytes):
	res = {'mcc': 0, 'mnc': 0, 'act': []}
	plmn_chars = 6
	act_chars = 4
	plmn_str = fivehexbytes[:plmn_chars]				# first three bytes (six ascii hex chars)
	act_str = fivehexbytes[plmn_chars:plmn_chars + act_chars]	# two bytes after first three bytes
	res['mcc'] = dec_mcc_from_plmn(plmn_str)
	res['mnc'] = dec_mnc_from_plmn(plmn_str)
	res['act'] = dec_act(act_str)
	return res

def format_xplmn_w_act(hexstr):
	s = ""
	for rec_data in hexstr_to_Nbytearr(hexstr, 5):
		rec_info = dec_xplmn_w_act(rec_data)
		if rec_info['mcc'] == 0xFFF and rec_info['mnc'] == 0xFFF:
			rec_str = "unused"
		else:
			rec_str = "MCC: %03d MNC: %03d AcT: %s" % (rec_info['mcc'], rec_info['mnc'], ", ".join(rec_info['act']))
		s += "\t%s # %s\n" % (rec_data, rec_str)
	return s

def dec_loci(hexstr):
	res = {'tmsi': '',  'mcc': 0, 'mnc': 0, 'lac': '', 'status': 0}
	res['tmsi'] = hexstr[:8]
	res['mcc'] = dec_mcc_from_plmn(hexstr[8:14])
	res['mnc'] = dec_mnc_from_plmn(hexstr[8:14])
	res['lac'] = hexstr[14:18]
	res['status'] = h2i(hexstr[20:22])
	return res

def dec_psloci(hexstr):
	res = {'p-tmsi': '', 'p-tmsi-sig': '', 'mcc': 0, 'mnc': 0, 'lac': '', 'rac': '', 'status': 0}
	res['p-tmsi'] = hexstr[:8]
	res['p-tmsi-sig'] = hexstr[8:14]
	res['mcc'] = dec_mcc_from_plmn(hexstr[14:20])
	res['mnc'] = dec_mnc_from_plmn(hexstr[14:20])
	res['lac'] = hexstr[20:24]
	res['rac'] = hexstr[24:26]
	res['status'] = h2i(hexstr[26:28])
	return res

def dec_epsloci(hexstr):
	res = {'guti': '', 'mcc': 0, 'mnc': 0, 'tac': '', 'status': 0}
	res['guti'] = hexstr[:24]
	res['tai'] = hexstr[24:34]
	res['mcc'] = dec_mcc_from_plmn(hexstr[24:30])
	res['mnc'] = dec_mnc_from_plmn(hexstr[24:30])
	res['tac'] = hexstr[30:34]
	res['status'] = h2i(hexstr[34:36])
	return res

def dec_xplmn(threehexbytes):
	res = {'mcc': 0, 'mnc': 0, 'act': []}
	plmn_chars = 6
	plmn_str = threehexbytes[:plmn_chars]				# first three bytes (six ascii hex chars)
	res['mcc'] = dec_mcc_from_plmn(plmn_str)
	res['mnc'] = dec_mnc_from_plmn(plmn_str)
	return res

def format_xplmn(hexstr):
	s = ""
	for rec_data in hexstr_to_Nbytearr(hexstr, 3):
		rec_info = dec_xplmn(rec_data)
		if rec_info['mcc'] == 0xFFF and rec_info['mnc'] == 0xFFF:
			rec_str = "unused"
		else:
			rec_str = "MCC: %03d MNC: %03d" % (rec_info['mcc'], rec_info['mnc'])
		s += "\t%s # %s\n" % (rec_data, rec_str)
	return s

def derive_milenage_opc(ki_hex, op_hex):
	"""
	Run the milenage algorithm to calculate OPC from Ki and OP
	"""
	from Crypto.Cipher import AES
	from Crypto.Util.strxor import strxor
	from pySim.utils import b2h

	# We pass in hex string and now need to work on bytes
	aes = AES.new(h2b(ki_hex))
	opc_bytes = aes.encrypt(h2b(op_hex))
	return b2h(strxor(opc_bytes, h2b(op_hex)))

def calculate_luhn(cc):
	"""
	Calculate Luhn checksum used in e.g. ICCID and IMEI
	"""
	num = map(int, str(cc))
	check_digit = 10 - sum(num[-2::-2] + [sum(divmod(d * 2, 10)) for d in num[::-2]]) % 10
	return 0 if check_digit == 10 else check_digit

def mcc_from_imsi(imsi):
	"""
	Derive the MCC (Mobile Country Code) from the first three digits of an IMSI
	"""
	if imsi == None:
		return None

	if len(imsi) > 3:
		return imsi[:3]
	else:
		return None

def mnc_from_imsi(imsi, long=False):
	"""
	Derive the MNC (Mobile Country Code) from the 4th to 6th digit of an IMSI
	"""
	if imsi == None:
		return None

	if len(imsi) > 3:
		if long:
			return imsi[3:6]
		else:
			return imsi[3:5]
	else:
		return None

def derive_mcc(digit1, digit2, digit3):
	"""
	Derive decimal representation of the MCC (Mobile Country Code)
	from three given digits.
	"""

	mcc = 0

	if digit1 != 0x0f:
		mcc += digit1 * 100
	if digit2 != 0x0f:
		mcc += digit2 * 10
	if digit3 != 0x0f:
		mcc += digit3

	return mcc

def derive_mnc(digit1, digit2, digit3=0x0f):
	"""
	Derive decimal representation of the MNC (Mobile Network Code)
	from two or (optionally) three given digits.
	"""

	mnc = 0

	# 3-rd digit is optional for the MNC. If present
	# the algorythm is the same as for the MCC.
	if digit3 != 0x0f:
		return derive_mcc(digit1, digit2, digit3)

	if digit1 != 0x0f:
		mnc += digit1 * 10
	if digit2 != 0x0f:
		mnc += digit2

	return mnc

def dec_msisdn(ef_msisdn):
	"""
	Decode MSISDN from EF.MSISDN or EF.ADN (same structure).
	See 3GPP TS 31.102, section 4.2.26 and 4.4.2.3.
	"""

	# Convert from str to (kind of) 'bytes'
	ef_msisdn = h2b(ef_msisdn)

	# Make sure mandatory fields are present
	if len(ef_msisdn) < 14:
		raise ValueError("EF.MSISDN is too short")

	# Skip optional Alpha Identifier
	xlen = len(ef_msisdn) - 14
	msisdn_lhv = ef_msisdn[xlen:]

	# Parse the length (in bytes) of the BCD encoded number
	bcd_len = ord(msisdn_lhv[0])
	# BCD length = length of dial num (max. 10 bytes) + 1 byte ToN and NPI
	if bcd_len == 0xff:
		return None
	elif bcd_len > 11 or bcd_len < 1:
		raise ValueError("Length of MSISDN (%d bytes) is out of range" % bcd_len)

	# Parse ToN / NPI
	ton = (ord(msisdn_lhv[1]) >> 4) & 0x07
	npi = ord(msisdn_lhv[1]) & 0x0f
	bcd_len -= 1

	# No MSISDN?
	if not bcd_len:
		return (npi, ton, None)

	msisdn = swap_nibbles(b2h(msisdn_lhv[2:][:bcd_len])).rstrip('f')
	# International number 10.5.118/3GPP TS 24.008
	if ton == 0x01:
		msisdn = '+' + msisdn

	return (npi, ton, msisdn)

def enc_msisdn(msisdn, npi=0x01, ton=0x03):
	"""
	Encode MSISDN as LHV so it can be stored to EF.MSISDN.
	See 3GPP TS 31.102, section 4.2.26 and 4.4.2.3.

	Default NPI / ToN values:
	  - NPI: ISDN / telephony numbering plan (E.164 / E.163),
	  - ToN: network specific or international number (if starts with '+').
	"""

	# Leading '+' indicates International Number
	if msisdn[0] == '+':
		msisdn = msisdn[1:]
		ton = 0x01

	# Append 'f' padding if number of digits is odd
	if len(msisdn) % 2 > 0:
		msisdn += 'f'

	# BCD length also includes NPI/ToN header
	bcd_len = len(msisdn) // 2 + 1
	npi_ton = (npi & 0x0f) | ((ton & 0x07) << 4) | 0x80
	bcd = rpad(swap_nibbles(msisdn), 10 * 2) # pad to 10 octets

	return ('%02x' % bcd_len) + ('%02x' % npi_ton) + bcd

def dec_st(st, table="sim"):
	"""
	Parses the EF S/U/IST and prints the list of available services in EF S/U/IST
	"""

	if table == "isim":
		from pySim.ts_31_103 import EF_IST_map
		lookup_map = EF_IST_map
	elif table == "usim":
		from pySim.ts_31_102 import EF_UST_map
		lookup_map = EF_UST_map
	else:
		from pySim.ts_51_011 import EF_SST_map
		lookup_map = EF_SST_map

	st_bytes = [st[i:i+2] for i in range(0, len(st), 2) ]

	avail_st = ""
	# Get each byte and check for available services
	for i in range(0, len(st_bytes)):
		# Byte i contains info about Services num (8i+1) to num (8i+8)
		byte = int(st_bytes[i], 16)
		# Services in each byte are in order MSB to LSB
		# MSB - Service (8i+8)
		# LSB - Service (8i+1)
		for j in range(1, 9):
			if byte&0x01 == 0x01 and ((8*i) + j in lookup_map):
				# Byte X contains info about Services num (8X-7) to num (8X)
				# bit = 1: service available
				# bit = 0: service not available
				avail_st += '\tService %d - %s\n' % ((8*i) + j, lookup_map[(8*i) + j])
			byte = byte >> 1
	return avail_st

def first_TLV_parser(bytelist):
	'''
	first_TLV_parser([0xAA, 0x02, 0xAB, 0xCD, 0xFF, 0x00]) -> (170, 2, [171, 205])

	parses first TLV format record in a list of bytelist
	returns a 3-Tuple: Tag, Length, Value
	Value is a list of bytes
	parsing of length is ETSI'style 101.220
	'''
	Tag = bytelist[0]
	if bytelist[1] == 0xFF:
		Len = bytelist[2]*256 + bytelist[3]
		Val = bytelist[4:4+Len]
	else:
		Len = bytelist[1]
		Val = bytelist[2:2+Len]
	return (Tag, Len, Val)

def TLV_parser(bytelist):
	'''
	TLV_parser([0xAA, ..., 0xFF]) -> [(T, L, [V]), (T, L, [V]), ...]

	loops on the input list of bytes with the "first_TLV_parser()" function
	returns a list of 3-Tuples
	'''
	ret = []
	while len(bytelist) > 0:
		T, L, V = first_TLV_parser(bytelist)
		if T == 0xFF:
			# padding bytes
			break
		ret.append( (T, L, V) )
		# need to manage length of L
		if L > 0xFE:
			bytelist = bytelist[ L+4 : ]
		else:
			bytelist = bytelist[ L+2 : ]
	return ret

def enc_st(st, service, state=1):
	"""
	Encodes the EF S/U/IST/EST and returns the updated Service Table

	Parameters:
		st - Current value of SIM/USIM/ISIM Service Table
		service - Service Number to encode as activated/de-activated
		state - 1 mean activate, 0 means de-activate

	Returns:
		s - Modified value of SIM/USIM/ISIM Service Table

	Default values:
		- state: 1 - Sets the particular Service bit to 1
	"""
	st_bytes = [st[i:i+2] for i in range(0, len(st), 2) ]

	s = ""
	# Check whether the requested service is present in each byte
	for i in range(0, len(st_bytes)):
		# Byte i contains info about Services num (8i+1) to num (8i+8)
		if service in range((8*i) + 1, (8*i) + 9):
			byte = int(st_bytes[i], 16)
			# Services in each byte are in order MSB to LSB
			# MSB - Service (8i+8)
			# LSB - Service (8i+1)
			mod_byte = 0x00
			# Copy bit by bit contents of byte to mod_byte with modified bit
			# for requested service
			for j in range(1, 9):
				mod_byte = mod_byte >> 1
				if service == (8*i) + j:
					mod_byte = state == 1 and mod_byte|0x80 or mod_byte&0x7f
				else:
					mod_byte = byte&0x01 == 0x01 and mod_byte|0x80 or mod_byte&0x7f
				byte = byte >> 1

			s += ('%02x' % (mod_byte))
		else:
			s += st_bytes[i]

	return s

def dec_epdgid(hexstr):
	"""
	Decode ePDG Id to get EF.ePDGId or EF.ePDGIdEm.
	See 3GPP TS 31.102 version 13.4.0 Release 13, section 4.2.102 and 4.2.104.
	"""

	# Convert from hex str to int bytes list
	epdgid_bytes = h2i(hexstr)

	s = ""

	# Get list of tuples containing parsed TLVs
	tlvs = TLV_parser(epdgid_bytes)

	for tlv in tlvs:
		# tlv = (T, L, [V])
		# T = Tag
		# L = Length
		# [V] = List of value

		# Invalid Tag value scenario
		if tlv[0] != 0x80:
			continue

		# Empty field - Zero length
		if tlv[1] == 0:
			continue

		# First byte in the value has the address type
		addr_type = tlv[2][0]
		# TODO: Support parsing of IPv4 and IPv6
		if addr_type == 0x00: #FQDN
			# Skip address tye byte i.e. first byte in value list
			content = tlv[2][1:]
			s += "\t%s # %s\n" % (i2h(content), i2s(content))

	return s

def enc_epdgid(epdg_addr, addr_type='00'):
	"""
	Encode ePDG Id so it can be stored to EF.ePDGId or EF.ePDGIdEm.
	See 3GPP TS 31.102 version 13.4.0 Release 13, section 4.2.102 and 4.2.104.

	Default values:
	  - addr_type: 00 - FQDN format of ePDG Address
	"""

	s = ""

	# TODO: Encoding of IPv4 and IPv6 address
	if addr_type == '00':
		hex_str = s2h(epdg_addr)
		s += '80' + ('%02x' % ((len(hex_str)//2)+1)) + '00' + hex_str

	return s

def sanitize_pin_adm(opts):
	"""
	The ADM pin can be supplied either in its hexadecimal form or as
	ascii string. This function checks the supplied opts parameter and
	returns the pin_adm as hex encoded string, regardles in which form
	it was originally supplied by the user
	"""

	pin_adm = None

	if opts.pin_adm is not None:
		if len(opts.pin_adm) <= 8:
			pin_adm = ''.join(['%02x'%(ord(x)) for x in opts.pin_adm])
			pin_adm = rpad(pin_adm, 16)

		else:
			raise ValueError("PIN-ADM needs to be <=8 digits (ascii)")

	if opts.pin_adm_hex is not None:
		if len(opts.pin_adm_hex) == 16:
			pin_adm = opts.pin_adm_hex
			# Ensure that it's hex-encoded
			try:
				try_encode = h2b(pin_adm)
			except ValueError:
				raise ValueError("PIN-ADM needs to be hex encoded using this option")
		else:
			raise ValueError("PIN-ADM needs to be exactly 16 digits (hex encoded)")

	return pin_adm

def init_reader(opts):
	"""
	Init card reader driver
	"""
	if opts.pcsc_dev is not None:
		print("Using PC/SC reader interface")
		from pySim.transport.pcsc import PcscSimLink
		sl = PcscSimLink(opts.pcsc_dev)
	elif opts.osmocon_sock is not None:
		print("Using Calypso-based (OsmocomBB) reader interface")
		from pySim.transport.calypso import CalypsoSimLink
		sl = CalypsoSimLink(sock_path=opts.osmocon_sock)
	elif opts.modem_dev is not None:
		print("Using modem for Generic SIM Access (3GPP TS 27.007)")
		from pySim.transport.modem_atcmd import ModemATCommandLink
		sl = ModemATCommandLink(device=opts.modem_dev, baudrate=opts.modem_baud)
	else: # Serial reader is default
		print("Using serial reader interface")
		from pySim.transport.serial import SerialSimLink
		sl = SerialSimLink(device=opts.device, baudrate=opts.baudrate)

	return sl