def main():
alice = ContactTracer()
bob = ContactTracer()
### Interaction ###
process_single_day(alice, bob)
process_single_day(alice, bob)
# Compute interaction time and process another day
interaction_time = datetime.fromtimestamp(alice.start_of_today)
interaction_time += timedelta(hours=10)
process_single_day(alice, bob, interaction_time)
print("... skipping 3 days ...\n")
for _ in range(4):
alice.next_day()
bob.next_day()
### Diagnosis and reporting ###
report_day(alice.start_of_today)
print("Bob is diagnosed with SARS-CoV-2")
bob_contagious_start = datetime.fromtimestamp(bob.start_of_today - 7 * 86400)
print(
"Doctor establishes that Bob started being contagious at {}".format(
bob_contagious_start
)
)
print("\n[Bob -> Server] Bob sends:")
tracing_info_bob = bob.get_tracing_information(bob_contagious_start)
bob_contagious_start_epoch, bob_contagious_key = tracing_info_bob
print(" * his key on {}: {}".format(bob_contagious_start, bob_contagious_key.hex()))
print(
" * the corresponding start time in epoch-seconds: {}\n".format(
bob_contagious_start_epoch
)
)
### Contact tracing ###
print("[Server] Compiles download batch\n")
release_time = bob.start_of_today + 4 * SECONDS_PER_BATCH
batch = TracingDataBatch([tracing_info_bob], release_time=release_time)
print("[Server -> Alice] Alice receives batch")
print(" * Alice checks if she was in contact with an infected person")
if alice.matches_with_batch(batch) > 0:
print(" * CORRECT: Alice's phone concludes she is at risk")
else:
print(" * ERROR: Alice's phone does not conclude she is at risk")
print("\n[Alice] Runs housekeeping to update her observation store")
alice.housekeeping_after_batch(batch)
def test_deleting_old_keys():
ct = ContactTracer(start_time=START_TIME)
ct.next_day()
ct.next_day()
assert len(ct.past_keys) > 0
old_day_key = ct.current_day_key
old_ephids = set(ct.current_ephids)
# Get with side-effects: deleting old keys
ct.get_tracing_information(START_TIME)
# Should delete all old keys
assert len(ct.past_keys) == 0
# Should pick a new day key
assert ct.current_day_key != old_day_key
# And all EphIDs should have been regenerated
assert len(set(ct.current_ephids).intersection(old_ephids)) == 0