Split all things into a more "library-like" package

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

pySim/cards.py

@@ -0,0 +1,259 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+""" pySim: Card programmation logic
+"""
+
+#
+# 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/>.
+#
+
+from pySim.utils import b2h, swap_nibbles, rpad, lpad
+
+
+class Card(object):
+
+	def __init__(self, scc):
+		self._scc = scc
+
+	def _e_iccid(self, iccid):
+		return swap_nibbles(iccid)
+
+	def _e_imsi(self, imsi):
+		"""Converts a string imsi into the value of the EF"""
+		l = (len(imsi) + 1) // 2	# Required bytes
+		oe = len(imsi) & 1			# Odd (1) / Even (0)
+		ei = '%02x' % l + swap_nibbles(lpad('%01x%s' % ((oe<<3)|1, imsi), 16))
+		return ei
+
+	def _e_plmn(self, mcc, mnc):
+		"""Converts integer MCC/MNC into 6 bytes for EF"""
+		return swap_nibbles(lpad('%d' % mcc, 3) + lpad('%d' % mnc, 3))
+
+	def reset(self):
+		self._scc.reset_card()
+
+
+class _MagicSimBase(Card):
+	"""
+	Theses cards uses several record based EFs to store the provider infos,
+	each possible provider uses a specific record number in each EF. The
+	indexes used are ( where N is the number of providers supported ) :
+	 - [2 .. N+1] for the operator name
+     - [1 .. N] for the programable EFs
+
+	* 3f00/7f4d/8f0c : Operator Name
+
+	bytes 0-15 : provider name, padded with 0xff
+	byte  16   : length of the provider name
+	byte  17   : 01 for valid records, 00 otherwise
+
+	* 3f00/7f4d/8f0d : Programmable Binary EFs
+
+	* 3f00/7f4d/8f0e : Programmable Record EFs
+
+	"""
+
+	@classmethod
+	def autodetect(kls, scc):
+		try:
+			for p, l, t in kls._files.values():
+				if not t:
+					continue
+				if scc.record_size(['3f00', '7f4d', p]) != l:
+					return None
+		except:
+			return None
+
+		return kls(scc)
+
+	def _get_count(self):
+		"""
+		Selects the file and returns the total number of entries
+		and entry size
+		"""
+		f = self._files['name']
+
+		r = self._scc.select_file(['3f00', '7f4d', f[0]])
+		rec_len = int(r[-1][28:30], 16)
+		tlen = int(r[-1][4:8],16)
+		rec_cnt = (tlen / rec_len) - 1;
+
+		if (rec_cnt < 1) or (rec_len != f[1]):
+			raise RuntimeError('Bad card type')
+
+		return rec_cnt
+
+	def program(self, p):
+		# Go to dir
+		self._scc.select_file(['3f00', '7f4d'])
+
+		# Home PLMN in PLMN_Sel format
+		hplmn = self._e_plmn(p['mcc'], p['mnc'])
+
+		# Operator name ( 3f00/7f4d/8f0c )
+		self._scc.update_record(self._files['name'][0], 2,
+			rpad(b2h(p['name']), 32)  + ('%02x' % len(p['name'])) + '01'
+		)
+
+		# ICCID/IMSI/Ki/HPLMN ( 3f00/7f4d/8f0d )
+		v = ''
+
+			# inline Ki
+		if self._ki_file is None:
+			v += p['ki']
+
+			# ICCID
+		v += '3f00' + '2fe2' + '0a' + self._e_iccid(p['iccid'])
+
+			# IMSI
+		v += '7f20' + '6f07' + '09' + self._e_imsi(p['imsi'])
+
+			# Ki
+		if self._ki_file:
+			v += self._ki_file + '10' + p['ki']
+
+			# PLMN_Sel
+		v+= '6f30' + '18' +  rpad(hplmn, 36)
+
+		self._scc.update_record(self._files['b_ef'][0], 1,
+			rpad(v, self._files['b_ef'][1]*2)
+		)
+
+		# SMSP ( 3f00/7f4d/8f0e )
+			# FIXME
+
+		# Write PLMN_Sel forcefully as well
+		r = self._scc.select_file(['3f00', '7f20', '6f30'])
+		tl = int(r[-1][4:8], 16)
+
+		hplmn = self._e_plmn(p['mcc'], p['mnc'])
+		self._scc.update_binary('6f30', hplmn + 'ff' * (tl-3))
+
+	def erase(self):
+		# Dummy
+		df = {}
+		for k, v in self._files.iteritems():
+			ofs = 1
+			fv = v[1] * 'ff'
+			if k == 'name':
+				ofs = 2
+				fv = fv[0:-4] + '0000'
+			df[v[0]] = (fv, ofs)
+
+		# Write
+		for n in range(0,self._get_count()):
+			for k, (msg, ofs) in df.iteritems():
+				self._scc.update_record(['3f00', '7f4d', k], n + ofs, msg)
+
+
+class SuperSim(_MagicSimBase):
+
+	name = 'supersim'
+
+	_files = {
+		'name' : ('8f0c', 18, True),
+		'b_ef' : ('8f0d', 74, True),
+		'r_ef' : ('8f0e', 50, True),
+	}
+
+	_ki_file = None
+
+
+class MagicSim(_MagicSimBase):
+
+	name = 'magicsim'
+
+	_files = {
+		'name' : ('8f0c', 18, True),
+		'b_ef' : ('8f0d', 130, True),
+		'r_ef' : ('8f0e', 102, False),
+	}
+
+	_ki_file = '6f1b'
+
+
+class FakeMagicSim(Card):
+	"""
+	Theses cards have a record based EF 3f00/000c that contains the provider
+	informations. See the program method for its format. The records go from
+	1 to N.
+	"""
+
+	name = 'fakemagicsim'
+
+	@classmethod
+	def autodetect(kls, scc):
+		try:
+			if scc.record_size(['3f00', '000c']) != 0x5a:
+				return None
+		except:
+			return None
+
+		return kls(scc)
+
+	def _get_infos(self):
+		"""
+		Selects the file and returns the total number of entries
+		and entry size
+		"""
+
+		r = self._scc.select_file(['3f00', '000c'])
+		rec_len = int(r[-1][28:30], 16)
+		tlen = int(r[-1][4:8],16)
+		rec_cnt = (tlen / rec_len) - 1;
+
+		if (rec_cnt < 1) or (rec_len != 0x5a):
+			raise RuntimeError('Bad card type')
+
+		return rec_cnt, rec_len
+
+	def program(self, p):
+		# Home PLMN
+		r = self._scc.select_file(['3f00', '7f20', '6f30'])
+		tl = int(r[-1][4:8], 16)
+
+		hplmn = self._e_plmn(p['mcc'], p['mnc'])
+		self._scc.update_binary('6f30', hplmn + 'ff' * (tl-3))
+
+		# Get total number of entries and entry size
+		rec_cnt, rec_len = self._get_infos()
+
+		# Set first entry
+		entry = (
+			'81' +								#  1b  Status: Valid & Active
+			rpad(b2h(p['name'][0:14]), 28) +	# 14b  Entry Name
+			self._e_iccid(p['iccid']) +			# 10b  ICCID
+			self._e_imsi(p['imsi']) +			#  9b  IMSI_len + id_type(9) + IMSI
+			p['ki'] +							# 16b  Ki
+			24*'f' + 'fd' + 24*'f' +			# 25b  (unknown ...)
+			rpad(p['smsp'], 20) +				# 10b  SMSP (padded with ff if needed)
+			10*'f'								#  5b  (unknown ...)
+		)
+		self._scc.update_record('000c', 1, entry)
+
+	def erase(self):
+		# Get total number of entries and entry size
+		rec_cnt, rec_len = self._get_infos()
+
+		# Erase all entries
+		entry = 'ff' * rec_len
+		for i in range(0, rec_cnt):
+			self._scc.update_record('000c', 1+i, entry)
+
+
+	# In order for autodetection ...
+_cards_classes = [ FakeMagicSim, SuperSim, MagicSim ]

pySim/commands.py

@@ -0,0 +1,93 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+""" pySim: SIM Card commands according to ISO 7816-4 and TS 11.11
+"""
+
+#
+# Copyright (C) 2009-2010  Sylvain Munaut <tnt@246tNt.com>
+# Copyright (C) 2010       Harald Welte <laforge@gnumonks.org>
+#
+# 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/>.
+#
+
+
+class SimCardCommands(object):
+	def __init__(self, transport):
+		self._tp = transport;
+
+	def select_file(self, dir_list):
+		rv = []
+		for i in dir_list:
+			data, sw = self._tp.send_apdu_checksw("a0a4000002" + i)
+			rv.append(data)
+		return rv
+
+	def read_binary(self, ef, length=None, offset=0):
+		if not hasattr(type(ef), '__iter__'):
+			ef = [ef]
+		r = self.select_file(ef)
+		if length is None:
+			length = int(r[-1][4:8], 16) - offset
+		pdu = 'a0b0%04x%02x' % (offset, (min(256, length) & 0xff))
+		return self._tp.send_apdu(pdu)
+
+	def update_binary(self, ef, data, offset=0):
+		if not hasattr(type(ef), '__iter__'):
+			ef = [ef]
+		self.select_file(ef)
+		pdu = 'a0d6%04x%02x' % (offset, len(data)/2) + data
+		return self._tp.send_apdu(pdu)
+
+	def read_record(self, ef, rec_no):
+		if not hasattr(type(ef), '__iter__'):
+			ef = [ef]
+		r = self.select_file(ef)
+		rec_length = int(r[-1][28:30], 16)
+		pdu = 'a0b2%02x04%02x' % (rec_no, rec_length)
+		return self._tp.send_apdu(pdu)
+
+	def update_record(self, ef, rec_no, data, force_len=False):
+		if not hasattr(type(ef), '__iter__'):
+			ef = [ef]
+		r = self.select_file(ef)
+		if not force_len:
+			rec_length = int(r[-1][28:30], 16)
+			if (len(data)/2 != rec_length):
+				raise ValueError('Invalid data length (expected %d, got %d)' % (rec_length, len(data)/2))
+		else:
+			rec_length = len(data)/2
+		pdu = ('a0dc%02x04%02x' % (rec_no, rec_length)) + data
+		return self._tp.send_apdu(pdu)
+
+	def record_size(self, ef):
+		r = self.select_file(ef)
+		return int(r[-1][28:30], 16)
+
+	def record_count(self, ef):
+		r = self.select_file(ef)
+		return int(r[-1][4:8], 16) // int(r[-1][28:30], 16)
+
+	def run_gsm(self, rand):
+		if len(rand) != 32:
+			raise ValueError('Invalid rand')
+		self.select_file(['3f00', '7f20'])
+		return self._tp.send_apdu('a088000010' + rand)
+
+	def reset_card(self):
+		return self._tp.reset_card()
+
+	def verify_chv(self, chv_no, code):
+		fc = rpad(b2h(code), 16)
+		return self.send_apdu('a02000' + ('%02x' % chv_no) + '08' + fc)

pySim/exceptions.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+""" pySim: Exceptions
+"""
+
+#
+# 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/>.
+#
+
+from __future__ import absolute_import
+
+import exceptions
+
+
+class NoCardError(exceptions.Exception):
+	pass
+
+class ProtocolError(exceptions.Exception):
+	pass

pySim/transport/pcsc.py

@@ -0,0 +1,104 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+""" pySim: PCSC reader transport link
+"""
+
+#
+# Copyright (C) 2009-2010  Sylvain Munaut <tnt@246tNt.com>
+# Copyright (C) 2010  Harald Welte <laforge@gnumonks.org>
+#
+# 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/>.
+#
+
+from smartcard.Exceptions import NoCardException
+from smartcard.System import readers
+from smartcard.CardConnectionObserver import ConsoleCardConnectionObserver
+
+from pySim.exceptions import NoCardError
+from pySim.utils import h2i, i2h
+
+
+class PcscSimLink(object):
+
+	def __init__(self, reader_number=0, observer=0):
+		r = readers();
+		try:
+			self._con = r[reader_number].createConnection()
+			if (observer):
+			    observer = ConsoleCardConnectionObserver()
+			    self._con.addObserver(observer)
+			self._con.connect()
+			#print r[reader_number], b2h(self._con.getATR())
+		except NoCardException:
+			raise NoCardError()
+
+	def __del__(self):
+		self._con.disconnect()
+		return
+
+	def reset_card(self):
+		self._con.disconnect()
+		try:
+			self._con.connect()
+		except NoCardException:
+			raise NoCardError()
+		return 1
+
+	def send_apdu_raw(self, pdu):
+		"""send_apdu_raw(pdu): Sends an APDU with minimal processing
+
+		   pdu    : string of hexadecimal characters (ex. "A0A40000023F00")
+		   return : tuple(data, sw), where
+		            data : string (in hex) of returned data (ex. "074F4EFFFF")
+		            sw   : string (in hex) of status word (ex. "9000")
+		"""
+		apdu = h2i(pdu)
+
+		data, sw1, sw2 = self._con.transmit(apdu)
+
+		sw = [sw1, sw2]
+
+		# Return value
+		return i2h(data), i2h(sw)
+
+	def send_apdu(self, pdu):
+		"""send_apdu(pdu): Sends an APDU and auto fetch response data
+
+		   pdu    : string of hexadecimal characters (ex. "A0A40000023F00")
+		   return : tuple(data, sw), where
+		            data : string (in hex) of returned data (ex. "074F4EFFFF")
+		            sw   : string (in hex) of status word (ex. "9000")
+		"""
+		data, sw = self.send_apdu_raw(pdu)
+
+		if (sw is not None) and (sw[0:2] == '9f'):
+			pdu_gr = pdu[0:2] + 'c00000' + sw[2:4]
+			data, sw = self.send_apdu_raw(pdu_gr)
+
+		return data, sw
+
+	def send_apdu_checksw(self, pdu, sw="9000"):
+		"""send_apdu_checksw(pdu,sw): Sends an APDU and check returned SW
+
+		   pdu    : string of hexadecimal characters (ex. "A0A40000023F00")
+		   sw     : string of 4 hexadecimal characters (ex. "9000")
+		   return : tuple(data, sw), where
+		            data : string (in hex) of returned data (ex. "074F4EFFFF")
+		            sw   : string (in hex) of status word (ex. "9000")
+		"""
+		rv = self.send_apdu(pdu)
+		if sw.lower() != rv[1]:
+			raise RuntimeError("SW match failed ! Expected %s and got %s." % (sw.lower(), rv[1]))
+		return rv

pySim/transport/serial.py

@@ -0,0 +1,214 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+""" pySim: Transport Link for serial (RS232) based readers included with simcard
+"""
+
+#
+# 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/>.
+#
+
+from __future__ import absolute_import
+
+import serial
+import time
+
+from pySim.exceptions import NoCardError, ProtocolError
+from pySim.utils import h2b, b2h
+
+
+class SerialSimLink(object):
+
+	def __init__(self, device='/dev/ttyUSB0', baudrate=9600, rst='-rts', debug=False):
+		self._sl = serial.Serial(
+				port = device,
+				parity = serial.PARITY_EVEN,
+				bytesize = serial.EIGHTBITS,
+				stopbits = serial.STOPBITS_TWO,
+				timeout = 1,
+				xonxoff = 0,
+				rtscts = 0,
+				baudrate = baudrate,
+			)
+		self._rst_pin = rst
+		self._debug = debug
+
+		rv = self.reset_card()
+		if rv == 0:
+			raise NoCardError()
+		elif rv < 0:
+			raise ProtocolError()
+
+	def __del__(self):
+		self._sl.close()
+
+	def reset_card(self):
+		rst_meth_map = {
+			'rts': self._sl.setRTS,
+			'dtr': self._sl.setDTR,
+		}
+		rst_val_map = { '+':0, '-':1 }
+
+		try:
+			rst_meth = rst_meth_map[self._rst_pin[1:]]
+			rst_val  = rst_val_map[self._rst_pin[0]]
+		except:
+			raise ValueError('Invalid reset pin %s' % self._rst_pin);
+
+		rst_meth(rst_val)
+		time.sleep(0.1)  # 100 ms
+		self._sl.flushInput()
+		rst_meth(rst_val ^ 1)
+
+		b = self._rx_byte()
+		if not b:
+			return 0
+		if ord(b) != 0x3b:
+			return -1;
+		self._dbg_print("TS: 0x%x Direct convention" % ord(b))
+
+		while ord(b) == 0x3b:
+			b = self._rx_byte()
+
+		if not b:
+			return -1
+		t0 = ord(b)
+		self._dbg_print("T0: 0x%x" % t0)
+
+		for i in range(4):
+			if t0 & (0x10 << i):
+				self._dbg_print("T%si = %x" % (chr(ord('A')+i), ord(self._rx_byte())))
+
+		for i in range(0, t0 & 0xf):
+			self._dbg_print("Historical = %x" % ord(self._rx_byte()))
+
+		while True:
+			x = self._rx_byte()
+			if not x:
+				break
+			self._dbg_print("Extra: %x" % ord(x))
+
+		return 1
+
+	def _dbg_print(self, s):
+		if self._debug:
+			print s
+
+	def _tx_byte(self, b):
+		self._sl.write(b)
+		r = self._sl.read()
+		if r != b:	# TX and RX are tied, so we must clear the echo
+			raise ProtocolError("Bad echo value. Expected %02x, got %s)" % (ord(b), '%02x'%ord(r) if r else '(nil)'))
+
+	def _tx_string(self, s):
+		"""This is only safe if it's guaranteed the card won't send any data
+		during the time of tx of the string !!!"""
+		self._sl.write(s)
+		r = self._sl.read(len(s))
+		if r != s:	# TX and RX are tied, so we must clear the echo
+			raise ProtocolError("Bad echo value (Expected: %s, got %s)" % (b2h(s), b2h(r)))
+
+	def _rx_byte(self):
+		return self._sl.read()
+
+	def send_apdu_raw(self, pdu):
+		"""send_apdu_raw(pdu): Sends an APDU with minimal processing
+
+		   pdu    : string of hexadecimal characters (ex. "A0A40000023F00")
+		   return : tuple(data, sw), where
+		            data : string (in hex) of returned data (ex. "074F4EFFFF")
+		            sw   : string (in hex) of status word (ex. "9000")
+		"""
+
+		pdu = h2b(pdu)
+		data_len = ord(pdu[4])	# P3
+
+		# Send first CLASS,INS,P1,P2,P3
+		self._tx_string(pdu[0:5])
+
+		# Wait ack which can be
+		#  - INS: Command acked -> go ahead
+		#  - 0x60: NULL, just wait some more
+		#  - SW1: The card can apparently proceed ...
+		while True:
+			b = self._rx_byte()
+			if b == pdu[1]:
+				break
+			elif b != '\x60':
+				# Ok, it 'could' be SW1
+				sw1 = b
+				sw2 = self._rx_byte()
+				nil = self._rx_byte()
+				if (sw2 and not nil):
+					return '', b2h(sw1+sw2)
+
+				raise ProtocolError()
+
+		# Send data (if any)
+		if len(pdu) > 5:
+			self._tx_string(pdu[5:])
+
+		# Receive data (including SW !)
+		#  length = [P3 - tx_data (=len(pdu)-len(hdr)) + 2 (SW1/2) ]
+		to_recv = data_len - len(pdu) + 5 + 2
+
+		data = ''
+		while (len(data) < to_recv):
+			b = self._rx_byte()
+			if (to_recv == 2) and (b == '\x60'): # Ignore NIL if we have no RX data (hack ?)
+				continue
+			if not b:
+				break;
+			data += b
+
+		# Split datafield from SW
+		if len(data) < 2:
+			return None, None
+		sw = data[-2:]
+		data = data[0:-2]
+
+		# Return value
+		return b2h(data), b2h(sw)
+
+	def send_apdu(self, pdu):
+		"""send_apdu(pdu): Sends an APDU and auto fetch response data
+
+		   pdu    : string of hexadecimal characters (ex. "A0A40000023F00")
+		   return : tuple(data, sw), where
+		            data : string (in hex) of returned data (ex. "074F4EFFFF")
+		            sw   : string (in hex) of status word (ex. "9000")
+		"""
+		data, sw = self.send_apdu_raw(pdu)
+
+		if (sw is not None) and (sw[0:2] == '9f'):
+			pdu_gr = pdu[0:2] + 'c00000' + sw[2:4]
+			data, sw = self.send_apdu_raw(pdu_gr)
+
+		return data, sw
+
+	def send_apdu_checksw(self, pdu, sw="9000"):
+		"""send_apdu_checksw(pdu,sw): Sends an APDU and check returned SW
+
+		   pdu    : string of hexadecimal characters (ex. "A0A40000023F00")
+		   sw     : string of 4 hexadecimal characters (ex. "9000")
+		   return : tuple(data, sw), where
+		            data : string (in hex) of returned data (ex. "074F4EFFFF")
+		            sw   : string (in hex) of status word (ex. "9000")
+		"""
+		rv = self.send_apdu(pdu)
+		if sw.lower() != rv[1]:
+			raise RuntimeError("SW match failed ! Expected %s and got %s." % (sw.lower(), rv[1]))
+		return rv

pySim/utils.py

@@ -0,0 +1,44 @@
+#!/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 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