def unregister(self, patient_uid, auth_token):
"""
Unregisters a patient from this hospital, and removes the patient from consistent storage, and removes all
patient records from local storage.
Raises Unauthorized if token is not valid.
Raises PatientNotRegistered if patient is not registered at this hospital.
"""
# Obtain the hashed UID.
hash_uid = hasher.hash(patient_uid)
# To perform authorization check, retrieve patient public key from consistent storage.
res = self.consistent_storage.get(hash_uid)
if not res['exists'] or not res['value']:
raise PatientNotRegistered(patient_uid)
# Verify the token against the patient's public key
pub_key = res['value']
if not self._verify_auth_token(pub_key, auth_token):
raise Unauthorized('missing or invalid token')
# If not, all good! Remove patient from consistent storage.
res = self.consistent_storage.remove(hash_uid)
if not res['removed']:
raise PatientConsistencyViolation('Remove', res['error'])
# Delete patient data from local storage.
self.local_storage.delete_key(hash_uid)
return True
def register(self, patient_name, patient_id, pub_key):
"""
Registers the patient to this hospital and stores the patient's
public key and patient ID in the consistent storage.
Raises PatientRegistrationExists if the patient is already registered in this hospital.
Raises PatientRegistrationViolation if the patient is already registered in another hospital.
"""
uid = patient_name + patient_id
hash_uid = hasher.hash(uid)
# First check if hashed UID resides in consistent storage, and get the owner of the key.
res = self.consistent_storage.get(hash_uid)
if res['exists']:
if res['is_owner']:
raise PatientRegistrationExists(uid)
else:
raise PatientRegistrationViolation(uid, res['owner'])
# Otherwise, perform a linearizable put request to consistent storage.
res = self.consistent_storage.put(hash_uid, pub_key)
if not res['ok']:
raise PatientRegistrationViolation(uid, res['owner'])
# Store medical record in local storage
record = MedicalRecord(
self.hospital_name,
uid,
notes=f'New registration at {self.hospital_name}')
self.local_storage.insert_item(hash_uid, pub_key, record)
# Return patient unique identifier
return uid
def read(self, patient_uid):
"""
Returns encrypted medical records for uid.
Returns an error if the patient has not registered with a hospital.
"""
med_records = []
# Obtain the hashed UID.
hash_uid = hasher.hash(patient_uid)
# Obtain the encrypted medical records.
med_records = self.local_storage.get_items(hash_uid)
return med_records
def transfer_request(self, hospital_id, patient_uid, patient_data,
signature):
"""
This RPC handler is invoked by another hospital to receive a transfer request for a patient.
"""
patient_data = patient_data.encode('utf-8')
# Obtain the hashed UID.
hash_uid = hasher.hash(patient_uid)
# Make sure that we are actually the owner of the patient uid.
# NOTE: This cannot be achieved with sagas, because different hospitals have a different
# view of the consistent storage state, and thus it is possible for the receiving
# hospital (i.e. this hospital) to not yet be the owner of the key at the time
# that this request is received.
# We shall just ignore this check, since there is no actual violation if we transfer
# encrypted patient data without actually transferring ownership of the key.
# if not self.consistent_storage.get(hash_uid)['is_owner']:
# raise PatientNotRegistered(patient_uid)
# If the patient already has data in our local storage, abort.
items = self.local_storage.get_items(hash_uid)
if items:
raise Unauthorized('patient data exists')
# Look up hospital in discovery service
hospital_info = self.discovery_svc.find_hospital(hospital_id)
if hospital_info is None:
raise PatientTransferInvalidHospital(hospital_id)
# Get public key of hospital and verify signature
pub_key = hospital_info['public_key']
if not crypto.verify(patient_data, signature,
crypto.load_pubkey(pub_key)):
raise Unauthorized('cannot verify transfer request')
# Load patient data into local storage.
decoded = base64.b64decode(patient_data).decode('utf-8')
records = json.loads(decoded)
self.local_storage.load_items(hash_uid, records)
# Return successful response to caller to complete the transfer.
return True
def prepopulate(num_cards, name):
bdb_root_url = getenv('BIGCHAIN_ROOT_URL')
if not bdb_root_url:
raise Exception('BIGCHAIN_ROOT_URL not set')
temp_backend = BigchaindbBackend(bdb_root_url)
_debug_print("Generating keys...")
public_key, private_key = crypto.generate_keys()
public_key = crypto.export_key(public_key)
private_key = crypto.export_key(private_key)
for i in range(num_cards):
patient_id = str(i)
hash_uid = hasher.hash(name + patient_id)
res = temp_backend.init_put(hash_uid, public_key)
if not res['ok']:
_debug_print("INIT PUT failed, aborting this PUT ...")
continue
_debug_print(f"{hash_uid} with pub_key:{public_key} put to bigchaindb")
file_name = PATH_TO_VOLUME + name + patient_id + "_personal_card.csv"
with open(file_name, 'w') as f:
writer = csv.writer(f,
delimiter=",",
quotechar='"',
quoting=csv.QUOTE_MINIMAL)
writer.writerow(['NAME', 'ID', 'UID', 'PUB_KEY', 'PRIV_KEY'])
writer.writerow(
[name, patient_id, hash_uid, public_key, private_key])
_debug_print(f"{hash_uid} with priv_key:{public_key} written to csv")
def write(self, physician_uid, patient_uid, data):
"""
Create medical record for patient and put in local storage.
"""
# Check that the physician has registered with this hospital.
if not self.local_storage.valid_staff(physician_uid):
raise PhysicianNotRegistered(physician_uid)
# Obtain the hashed UID.
hash_uid = hasher.hash(patient_uid)
# Retrieve patient public key from consistent storage.
res = self.consistent_storage.get(hash_uid)
if not res['exists'] or not res['value']:
raise PatientNotRegistered(patient_uid)
pub_key = res['value']
# Store medical record in local storage
record = MedicalRecord(physician_uid, patient_uid, data)
self.local_storage.insert_item(hash_uid, pub_key, record)
return True
def transfer(self, patient_uid, auth_token, dest_hospital):
"""
Transfers a patient registration from the current hospital to a new one.
Raises Unauthorized if token is not valid.
Raises PatientNotRegistered if patient is not registered at this hospital.
"""
# Obtain the hashed UID.
hash_uid = hasher.hash(patient_uid)
# To perform authorization check, retrieve patient public key from consistent storage.
res = self.consistent_storage.get(hash_uid)
if not res['exists'] or not res['value']:
raise PatientNotRegistered(patient_uid)
# Verify the token against the patient's public key
pub_key = res['value']
if not self._verify_auth_token(pub_key, auth_token):
raise Unauthorized('missing or invalid token')
# Look up destination hospital in discovery service
dest_hospital_info = self.discovery_svc.find_hospital(dest_hospital)
if dest_hospital_info is None:
raise PatientTransferInvalidHospital(dest_hospital)
# Make sure we are not transferring to ourselves.
if dest_hospital_info['id'] == self.discovery_svc.get_id():
raise PatientTransferInvalidHospital(dest_hospital)
# If not, all good! Transfer patient in consistent storage.
res = self.consistent_storage.transfer(hash_uid, dest_hospital)
if not res['transferred']:
raise PatientConsistencyViolation('Transfer', res['error'])
# Now we actually transfer the encrypted patient data to the target hospital.
# TODO: Maybe make this part of the request asynchronous? (i.e. push onto a work queue)
# Add a new record for patient to signify the transfer to a new hospital
dest_hospital_name = dest_hospital_info['name']
transfer_record = MedicalRecord(
self.hospital_name,
patient_uid,
notes=f'Transferred to {dest_hospital_name}')
self.local_storage.insert_item(hash_uid, pub_key, transfer_record)
# Retrieve private key from discovery service
hospital_id = self.discovery_svc.get_id()
priv_key = self.discovery_svc.get_private_key()
# Serialize and encode all patient data
records = self.local_storage.get_items(hash_uid)
data = json.dumps(records)
encoded = base64.b64encode(data.encode('utf-8'))
# Sign the encoded data to get a signature
signature = crypto.sign(encoded, crypto.load_privkey(priv_key)).hex()
# Send out the transfer request to the target hospital
addr = dest_hospital_info['gateway_addr']
url = f'http://{addr}/transfer_request'
payload = {
'hospital_id': hospital_id,
'uid': patient_uid,
'data': encoded.decode('utf-8'),
'signature': signature,
}
try:
res = requests.post(url, json=payload)
res.raise_for_status()
except requests.HTTPError as e:
# If there's an error raised here, unfortunately the transfer
# cannot be rolled back. If only we had actual sagas here...
# In this case, the patient's data is still in this hospital even though
# the destination hospital now owns the patient registration.
if res.json().get('error'):
raise PatientTransferRequestFailed(dest_hospital,
res.json().get('error'))
raise PatientTransferRequestFailed(dest_hospital, str(e))
# Make sure that response is valid
res = res.json()
success = res.get('success')
if not success:
raise PatientTransferRequestFailed(dest_hospital, res.get('error'))
# Now we can remove the patient from our local storage
self.local_storage.delete_key(hash_uid)
return True