def _decrypt_token(self, id_phone, ciphertext):
"""
decrypts incoming tokens from SmartPhones
if decryption succeeds, datetime of id_phone is updated
alerts on invalid token, datetime not updated
:param id_phone: skt of the token's phone
:param ciphertext: ciphertext encrypted from beacon
:return: None
"""
update_execution_log(["New Token", id_phone, ciphertext])
print("New Token from ID Phone: {0}, Ciphertext: {1}".format(
id_phone, ciphertext))
key = self._get_key(id_phone)
if key is not None:
try:
new_datetime_string = Fernet(key).decrypt(
str.encode(ciphertext)).decode()
new_datetime = dt.strptime(new_datetime_string,
database_dt_format)
database_datetime = dt.strptime(self._database[id_phone][2],
database_dt_format)
if new_datetime > database_datetime:
self._database[id_phone][2] = new_datetime_string
with open(self._database_path, 'w') as j:
json.dump(self._database, j, indent=0)
except InvalidToken:
update_execution_log(["Invalid Token", id_phone, ciphertext])
def random_bluetooth(self, prob=0.5):
"""
called when the phone's bluetooth is off
:param prob: probability of phone's bluetooth turning on
:return:
"""
update_execution_log(["Smartphone Bluetooth Off", self._id_phone])
self._bluetooth = False if random.rand() < prob else True
def random_on(self, prob=0.5):
"""
called when the phone is off
:param prob: probability of phone turning on
:return: None
"""
update_execution_log(["Smartphone Off", self._id_phone])
self._on = False if random.rand() < prob else True
def routine(self, id_phone, id_beacon, key):
"""
Health Authority starts a client session to communicate a new patient
:param id_phone: skt of the new patient's phone
:param id_beacon: identifies the beacon associated to the patient
:param key: key for symmetric encryption
:return: None
"""
update_execution_log([health_authority_header, id_phone, id_beacon, key])
self._client_session(separator.join([health_authority_header, id_phone, id_beacon, key]))
def add_beacon(self, id_beacon, info):
"""
stores a new id_beacon with info into AuthorityBackend database
:param id_beacon: identifies the new beacon added
:param info: info regarding the new patient
:return: None
"""
update_execution_log(["New Beacon", id_beacon, info])
self._database[id_beacon] = info
with open(self._database_path, 'w') as j:
json.dump(self._database, j, indent=0)
def _get_key(self, id_phone):
"""
retrieves key for symmetric encryption of id_phone
alerts on invalid id_phone
:param id_phone: skt of the phone sending the ciphertext to AppBackend
:return: 44bit key
"""
if id_phone in self._database:
return self._database[id_phone][1]
else:
update_execution_log(["Invalid Phone", id_phone])
def control_routine(self, td_expire):
"""
control routine used to check violations
if datetime expires, AppBackend sends an alert to AuthorityBackend
:param td_expire: time tolerance from last datetime update
:return: None
"""
for id_phone in self._database:
id_beacon = self._database[id_phone][0]
expire_dt = dt.strptime(self._database[id_phone][2],
database_dt_format) + td(seconds=td_expire)
if dt.utcnow() > expire_dt:
update_execution_log([app_header, id_beacon])
self._client_session(separator.join([app_header, id_beacon]))
def _add_phone(self, id_phone, id_beacon, key):
"""
adds a new phone to AppBackend's database
stores the actual datetime
database is stored on a json file in the root directory of AppBackend
:param id_phone: skt of the phone
:param id_beacon: identifies the associated beacon
:param key: key for symmetric encryption
:return: None
"""
update_execution_log(["New Patient", id_phone, id_beacon, key])
self._database[id_phone] = [
id_beacon, key,
dt.utcnow().strftime(database_dt_format)
]
with open(self._database_path, 'w') as j:
json.dump(self._database, j, indent=0)
def routine(self, on=True, prob=0.5):
"""
can't build up properly Bluetooth transmission
transmissions are simulated through a header.txt file
if beacon is on, encrypts a plaintext for the SmartPhone on the header.txt file
if beacon is off, there's no encryption and the file is truncated
:param on: routine changes according to beacon on/off status
:param prob: probability of beacon turning on
:return: None
"""
if on:
plaintext = str.encode(dt.utcnow().strftime(database_dt_format))
ciphertext = Fernet(self._key).encrypt(plaintext).decode()
update_execution_log(
["New Encryption", self._id_beacon, self._header, ciphertext])
with open(self._packet, "w") as f:
f.write(ciphertext)
else:
update_execution_log(["Beacon Off", self._id_beacon, self._header])
open(self._packet, "w").close()
self._on = False if random.rand() < prob else True
def routine(self, wifi=True, prob=0.5):
"""
if wifi is on, forwards the last token received
if wifi is off, stores all incoming tokens into a log file
if wifi turns on, last stored token is sent to AppBackend
:param wifi: routine changes according to phone's wifi on/off status
:param prob: probability of phone's wifi turning on
:return: None
"""
last_ciphertext = None
for packet in [packet for packet in os.listdir(self._packets_root) if packet.startswith(self._header)]:
if os.path.getsize(os.path.join(self._packets_root, packet)) > 0:
with open(os.path.join(self._packets_root, packet), "r") as f:
ciphertext = f.read()
if wifi:
update_execution_log([smartphone_header, self._id_phone, ciphertext])
self._client_session(separator.join([smartphone_header, self._id_phone, ciphertext]))
else:
last_ciphertext = ciphertext
with open(self._log_path, "w") as j:
self._log[dt.utcnow().strftime(database_dt_format)] = last_ciphertext
json.dump(self._log, j, indent=0)
if not wifi:
update_execution_log(["Smartphone WiFi Off", self._id_phone])
self._wifi = False if random.rand() < prob else True
if self._wifi and last_ciphertext is not None:
update_execution_log([smartphone_header, self._id_phone, last_ciphertext])
self._client_session(separator.join([smartphone_header, self._id_phone, last_ciphertext]))
def _add_datetime(self, id_beacon):
"""
adds to log the datetime of id_beacon's violation
:param id_beacon: identifies the beacon involved in the violation
:return: None
"""
update_execution_log(
["Quarantine Violation", id_beacon, self._database[id_beacon]])
print("Quarantine Violation from ID Beacon: {0}, Info: {1}".format(
id_beacon, self._database[id_beacon]))
if id_beacon in self._database:
if id_beacon not in self._log:
self._log[id_beacon] = [
dt.utcnow().strftime(database_dt_format)
]
else:
self._log[id_beacon].append(
dt.utcnow().strftime(database_dt_format))
with open(self._log_path, 'w') as j:
json.dump(self._log, j, indent=0)
else:
update_execution_log(["Invalid Beacon", id_beacon])
