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test_fernet.py
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test_fernet.py
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# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
import base64
import calendar
import json
import os
import time
import iso8601
import pretend
import pytest
from cryptography.fernet import Fernet, InvalidToken, MultiFernet
from cryptography.hazmat.primitives.ciphers import algorithms, modes
import cryptography_vectors
def json_parametrize(keys, filename):
vector_file = cryptography_vectors.open_vector_file(
os.path.join("fernet", filename), "r"
)
with vector_file:
data = json.load(vector_file)
return pytest.mark.parametrize(
keys, [tuple([entry[k] for k in keys]) for entry in data]
)
@pytest.mark.supported(
only_if=lambda backend: backend.cipher_supported(
algorithms.AES(b"\x00" * 32), modes.CBC(b"\x00" * 16)
),
skip_message="Does not support AES CBC",
)
class TestFernet(object):
@json_parametrize(
("secret", "now", "iv", "src", "token"),
"generate.json",
)
def test_generate(self, secret, now, iv, src, token, backend):
f = Fernet(secret.encode("ascii"), backend=backend)
actual_token = f._encrypt_from_parts(
src.encode("ascii"),
calendar.timegm(iso8601.parse_date(now).utctimetuple()),
bytes(iv),
)
assert actual_token == token.encode("ascii")
@json_parametrize(
("secret", "now", "src", "ttl_sec", "token"),
"verify.json",
)
def test_verify(
self, secret, now, src, ttl_sec, token, backend, monkeypatch
):
f = Fernet(secret.encode("ascii"), backend=backend)
current_time = calendar.timegm(iso8601.parse_date(now).utctimetuple())
payload = f.decrypt_at_time(
token.encode("ascii"),
ttl=ttl_sec,
current_time=current_time,
)
assert payload == src.encode("ascii")
monkeypatch.setattr(time, "time", lambda: current_time)
payload = f.decrypt(token.encode("ascii"), ttl=ttl_sec)
assert payload == src.encode("ascii")
@json_parametrize(("secret", "token", "now", "ttl_sec"), "invalid.json")
def test_invalid(self, secret, token, now, ttl_sec, backend, monkeypatch):
f = Fernet(secret.encode("ascii"), backend=backend)
current_time = calendar.timegm(iso8601.parse_date(now).utctimetuple())
with pytest.raises(InvalidToken):
f.decrypt_at_time(
token.encode("ascii"),
ttl=ttl_sec,
current_time=current_time,
)
monkeypatch.setattr(time, "time", lambda: current_time)
with pytest.raises(InvalidToken):
f.decrypt(token.encode("ascii"), ttl=ttl_sec)
def test_invalid_start_byte(self, backend):
f = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
with pytest.raises(InvalidToken):
f.decrypt(base64.urlsafe_b64encode(b"\x81"))
def test_timestamp_too_short(self, backend):
f = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
with pytest.raises(InvalidToken):
f.decrypt(base64.urlsafe_b64encode(b"\x80abc"))
def test_non_base64_token(self, backend):
f = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
with pytest.raises(InvalidToken):
f.decrypt(b"\x00")
def test_unicode(self, backend):
f = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
with pytest.raises(TypeError):
f.encrypt("") # type: ignore[arg-type]
with pytest.raises(TypeError):
f.decrypt("") # type: ignore[arg-type]
def test_timestamp_ignored_no_ttl(self, monkeypatch, backend):
f = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
pt = b"encrypt me"
token = f.encrypt(pt)
monkeypatch.setattr(time, "time", pretend.raiser(ValueError))
assert f.decrypt(token, ttl=None) == pt
def test_ttl_required_in_decrypt_at_time(self, monkeypatch, backend):
f = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
pt = b"encrypt me"
token = f.encrypt(pt)
with pytest.raises(ValueError):
f.decrypt_at_time(
token,
ttl=None, # type: ignore[arg-type]
current_time=int(time.time()),
)
@pytest.mark.parametrize("message", [b"", b"Abc!", b"\x00\xFF\x00\x80"])
def test_roundtrips(self, message, backend):
f = Fernet(Fernet.generate_key(), backend=backend)
assert f.decrypt(f.encrypt(message)) == message
def test_bad_key(self, backend):
with pytest.raises(ValueError):
Fernet(base64.urlsafe_b64encode(b"abc"), backend=backend)
def test_extract_timestamp(self, monkeypatch, backend):
f = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
current_time = 1526138327
token = f.encrypt_at_time(b"encrypt me", current_time)
assert f.extract_timestamp(token) == current_time
with pytest.raises(InvalidToken):
f.extract_timestamp(b"nonsensetoken")
@pytest.mark.supported(
only_if=lambda backend: backend.cipher_supported(
algorithms.AES(b"\x00" * 32), modes.CBC(b"\x00" * 16)
),
skip_message="Does not support AES CBC",
)
class TestMultiFernet(object):
def test_encrypt(self, backend):
f1 = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
f2 = Fernet(base64.urlsafe_b64encode(b"\x01" * 32), backend=backend)
f = MultiFernet([f1, f2])
assert f1.decrypt(f.encrypt(b"abc")) == b"abc"
def test_decrypt(self, backend):
f1 = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
f2 = Fernet(base64.urlsafe_b64encode(b"\x01" * 32), backend=backend)
f = MultiFernet([f1, f2])
assert f.decrypt(f1.encrypt(b"abc")) == b"abc"
assert f.decrypt(f2.encrypt(b"abc")) == b"abc"
with pytest.raises(InvalidToken):
f.decrypt(b"\x00" * 16)
def test_decrypt_at_time(self, backend):
f1 = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
f = MultiFernet([f1])
pt = b"encrypt me"
token = f.encrypt_at_time(pt, current_time=100)
assert f.decrypt_at_time(token, ttl=1, current_time=100) == pt
with pytest.raises(InvalidToken):
f.decrypt_at_time(token, ttl=1, current_time=102)
with pytest.raises(ValueError):
f.decrypt_at_time(
token, ttl=None, current_time=100 # type: ignore[arg-type]
)
def test_no_fernets(self, backend):
with pytest.raises(ValueError):
MultiFernet([])
def test_non_iterable_argument(self, backend):
with pytest.raises(TypeError):
MultiFernet(None) # type: ignore[arg-type]
def test_rotate(self, backend):
f1 = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
f2 = Fernet(base64.urlsafe_b64encode(b"\x01" * 32), backend=backend)
mf1 = MultiFernet([f1])
mf2 = MultiFernet([f2, f1])
plaintext = b"abc"
mf1_ciphertext = mf1.encrypt(plaintext)
assert mf2.decrypt(mf1_ciphertext) == plaintext
rotated = mf2.rotate(mf1_ciphertext)
assert rotated != mf1_ciphertext
assert mf2.decrypt(rotated) == plaintext
with pytest.raises(InvalidToken):
mf1.decrypt(rotated)
def test_rotate_preserves_timestamp(self, backend, monkeypatch):
f1 = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
f2 = Fernet(base64.urlsafe_b64encode(b"\x01" * 32), backend=backend)
mf1 = MultiFernet([f1])
mf2 = MultiFernet([f2, f1])
plaintext = b"abc"
original_time = int(time.time()) - 5 * 60
mf1_ciphertext = mf1.encrypt_at_time(plaintext, original_time)
rotated_time, _ = Fernet._get_unverified_token_data(
mf2.rotate(mf1_ciphertext)
)
assert int(time.time()) != rotated_time
assert original_time == rotated_time
def test_rotate_decrypt_no_shared_keys(self, backend):
f1 = Fernet(base64.urlsafe_b64encode(b"\x00" * 32), backend=backend)
f2 = Fernet(base64.urlsafe_b64encode(b"\x01" * 32), backend=backend)
mf1 = MultiFernet([f1])
mf2 = MultiFernet([f2])
with pytest.raises(InvalidToken):
mf2.rotate(mf1.encrypt(b"abc"))