def calculate_crc(key):
"""Calculate the CRC16 and compare it."""
print_debug(3, "Starting to compute CRC-16-genibus")
keylen = len(key)
keystring = [chr(b) for b in key[:keylen - 2]]
print_debug(3, "ASCII key: " + str(keystring))
crc = predefined.Crc("crc-16-genibus")
crc.update(keystring)
crc_keydata = int(crc.hexdigest(), 16)
# Do it like the game does, because it's funny
constant = [0x5D, 0x10, 0x7A, 0x33, 0x00, 0x77, 0x13, 0x92, 0xDE]
constant.reverse()
constant = [(~b) & 0xFF for b in constant]
constant = [chr(b) for b in constant]
crc = predefined.Crc("crc-16-genibus")
crc.update(constant)
crc_constantdata = int(crc.hexdigest(), 16) # It's always 0x00D3
# Mix CRC
crc_key = crc_constantdata ^ crc_keydata ^ 0x62D3
print_debug(
3, "Key CRC: " + hex(crc_keydata) + ", constant CRC: " +
hex(crc_constantdata) + ", final CRC: " + hex(crc_key))
return crc_key
def MODBUSCrc(payload):
'''
Have MODBUS CRC of the payload.
Reference from http://crcmod.sourceforge.net/crcmod.predefined.html
'''
modbuscrc = predefined.Crc("modbus")
modbuscrc.update(payload)
return modbuscrc.crcValue
def try_parse(packet=""):
packet_CRC = packet[-4:]
check_CRC = detect.Crc('crc-16')
check_CRC.update((packet[:-4]).encode('utf-8'))
if packet_CRC == check_CRC.hexdigest():
p_components = packet[:-4].split(MeshConfiguration.separator)
route = classes.Route.from_string(p_components[0], p_components[1],
p_components[2], p_components[3])
command = classes.Command.from_string(p_components[4],
p_components[5],
p_components[6])
return Packet(route=route, command=command)
else:
raise exceptions.CorruptPacketException(
['CRC code did not match.', packet])
def computeHashProb(name_set, hash_function):
probability = 1.0
hash_set = set()
collisions = 0.0
for name in name_set:
hash_fun = crc.Crc(hash_function)
hash_fun.update(name)
hash_res = hash_fun.hexdigest()
if hash_res not in hash_set:
hash_set.add(hash_res)
else:
collisions += 1.0
#print "collisions holds %.2f" % collisions
if (name_set.__len__() is not 0):
probability = collisions / name_set.__len__()
return probability
def computeHash(self):
hash_fun = crc.Crc(self.hash_func)
hash_fun.update(self.nameEntry.get_name(delimiter=""))
return hash_fun.hexdigest()
def crc16(self):
crc = detect.Crc('crc-16')
crc.update(str(self).encode('utf-8'))
return crc.hexdigest()
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from crcmod import predefined
def MODBUSCrc(payload):
'''
Have MODBUS CRC of the payload.
Reference from http://crcmod.sourceforge.net/crcmod.predefined.html
'''
modbuscrc = predefined.Crc("modbus")
modbuscrc.update(payload)
return modbuscrc.crcValue
if __name__ == "__main__":
modbuscrc = predefined.Crc("modbus")
modbuscrc.update(b"123456789")
print(modbuscrc)
print(hex(MODBUSCrc(b"123456789")).upper())
print(hex(MODBUSCrc(b"987654321")).upper())