forked from Telos4/LoRa-Workshop
101 lines
2.7 KiB
Python
101 lines
2.7 KiB
Python
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#
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# frm_payload: appnonce(3) netid(3) devaddr(4) dlsettings(1) rxdelay(1) cflist(0..16)
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#
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from .MalformedPacketException import MalformedPacketException
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from .AES_CMAC import AES_CMAC
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import ucryptolib
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MODE_ECB = 1
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class JoinAcceptPayload:
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def read(self, payload):
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if len(payload) < 12:
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raise MalformedPacketException("Invalid join accept")
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self.encrypted_payload = payload
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def create(self, args):
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pass
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def length(self):
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return len(self.encrypted_payload)
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def to_raw(self):
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return self.encrypted_payload
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def to_clear_raw(self):
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return self.payload
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def get_appnonce(self):
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return self.appnonce
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def get_netid(self):
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return self.netid
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def get_devaddr(self):
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return list(map(int, reversed(self.devaddr)))
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def get_dlsettings(self):
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return self.dlsettings
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def get_rxdelay(self):
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return self.rxdelay
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def get_cflist(self):
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return self.cflist
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def compute_mic(self, key, direction, mhdr):
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mic = []
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mic += [mhdr.to_raw()]
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mic += self.to_clear_raw()
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cmac = AES_CMAC()
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computed_mic = cmac.encode(bytes(key), bytes(mic))[:4]
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return list(map(int, computed_mic))
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def decrypt_payload(self, key, direction, mic):
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a = []
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a += self.encrypted_payload
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a += mic
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cipher = ucryptolib.aes(bytearray(key), MODE_ECB)
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self.payload = cipher.encrypt(bytes(a))[:-4]
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self.appnonce = self.payload[:3]
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self.netid = self.payload[3:6]
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self.devaddr = self.payload[6:10]
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self.dlsettings = self.payload[10]
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self.rxdelay = self.payload[11]
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self.cflist = None
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if self.payload[12:]:
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self.cflist = self.payload[12:]
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return list(map(int, self.payload))
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def encrypt_payload(self, key, direction, mhdr):
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a = []
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a += self.to_clear_raw()
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a += self.compute_mic(key, direction, mhdr)
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cipher = ucryptolib.aes(bytearray(key), MODE_ECB)
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return list(map(int, cipher.decrypt(bytes(a))))
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def derive_nwskey(self, key, devnonce):
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a = [0x01]
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a += self.get_appnonce()
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a += self.get_netid()
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a += devnonce
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a += [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
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cipher = ucryptolib.aes(bytearray(key), MODE_ECB)
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return list(map(int, cipher.encrypt(bytes(a))))
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def derive_appskey(self, key, devnonce):
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a = [0x02]
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a += self.get_appnonce()
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a += self.get_netid()
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a += devnonce
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a += [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
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cipher = ucryptolib.aes(bytearray(key), MODE_ECB)
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return list(map(int, cipher.encrypt(bytes(a))))
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