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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 binascii
import os
import pytest
from cryptography.hazmat.primitives.ciphers import algorithms, base, modes
from .utils import generate_aead_test
from ...utils import load_nist_vectors
@pytest.mark.supported(
only_if=lambda backend: backend.cipher_supported(
algorithms.AES(b"\x00" * 16), modes.GCM(b"\x00" * 12)
),
skip_message="Does not support AES GCM",
)
class TestAESModeGCM:
test_gcm = generate_aead_test(
load_nist_vectors,
os.path.join("ciphers", "AES", "GCM"),
[
"gcmDecrypt128.rsp",
"gcmDecrypt192.rsp",
"gcmDecrypt256.rsp",
"gcmEncryptExtIV128.rsp",
"gcmEncryptExtIV192.rsp",
"gcmEncryptExtIV256.rsp",
],
algorithms.AES,
modes.GCM,
)
def test_gcm_tag_with_only_aad(self, backend):
key = binascii.unhexlify(b"5211242698bed4774a090620a6ca56f3")
iv = binascii.unhexlify(b"b1e1349120b6e832ef976f5d")
aad = binascii.unhexlify(b"b6d729aab8e6416d7002b9faa794c410d8d2f193")
tag = binascii.unhexlify(b"0f247e7f9c2505de374006738018493b")
cipher = base.Cipher(
algorithms.AES(key), modes.GCM(iv), backend=backend
)
encryptor = cipher.encryptor()
encryptor.authenticate_additional_data(aad)
encryptor.finalize()
assert encryptor.tag == tag
def test_gcm_ciphertext_with_no_aad(self, backend):
key = binascii.unhexlify(b"e98b72a9881a84ca6b76e0f43e68647a")
iv = binascii.unhexlify(b"8b23299fde174053f3d652ba")
ct = binascii.unhexlify(b"5a3c1cf1985dbb8bed818036fdd5ab42")
tag = binascii.unhexlify(b"23c7ab0f952b7091cd324835043b5eb5")
pt = binascii.unhexlify(b"28286a321293253c3e0aa2704a278032")
cipher = base.Cipher(
algorithms.AES(key), modes.GCM(iv), backend=backend
)
encryptor = cipher.encryptor()
computed_ct = encryptor.update(pt) + encryptor.finalize()
assert computed_ct == ct
assert encryptor.tag == tag
def test_gcm_ciphertext_limit(self, backend):
encryptor = base.Cipher(
algorithms.AES(b"\x00" * 16),
modes.GCM(b"\x01" * 16),
backend=backend,
).encryptor()
new_max = modes.GCM._MAX_ENCRYPTED_BYTES - 16
encryptor._bytes_processed = new_max # type: ignore[attr-defined]
encryptor.update(b"0" * 16)
max = modes.GCM._MAX_ENCRYPTED_BYTES
assert encryptor._bytes_processed == max # type: ignore[attr-defined]
with pytest.raises(ValueError):
encryptor.update(b"0")
def test_gcm_aad_limit(self, backend):
encryptor = base.Cipher(
algorithms.AES(b"\x00" * 16),
modes.GCM(b"\x01" * 16),
backend=backend,
).encryptor()
new_max = modes.GCM._MAX_AAD_BYTES - 16
encryptor._aad_bytes_processed = new_max # type: ignore[attr-defined]
encryptor.authenticate_additional_data(b"0" * 16)
max = modes.GCM._MAX_AAD_BYTES
assert (
encryptor._aad_bytes_processed == max # type: ignore[attr-defined]
)
with pytest.raises(ValueError):
encryptor.authenticate_additional_data(b"0")
def test_gcm_ciphertext_increments(self, backend):
encryptor = base.Cipher(
algorithms.AES(b"\x00" * 16),
modes.GCM(b"\x01" * 16),
backend=backend,
).encryptor()
encryptor.update(b"0" * 8)
assert encryptor._bytes_processed == 8 # type: ignore[attr-defined]
encryptor.update(b"0" * 7)
assert encryptor._bytes_processed == 15 # type: ignore[attr-defined]
encryptor.update(b"0" * 18)
assert encryptor._bytes_processed == 33 # type: ignore[attr-defined]
def test_gcm_aad_increments(self, backend):
encryptor = base.Cipher(
algorithms.AES(b"\x00" * 16),
modes.GCM(b"\x01" * 16),
backend=backend,
).encryptor()
encryptor.authenticate_additional_data(b"0" * 8)
assert (
encryptor._aad_bytes_processed == 8 # type: ignore[attr-defined]
)
encryptor.authenticate_additional_data(b"0" * 18)
assert (
encryptor._aad_bytes_processed == 26 # type: ignore[attr-defined]
)
def test_gcm_tag_decrypt_none(self, backend):
key = binascii.unhexlify(b"5211242698bed4774a090620a6ca56f3")
iv = binascii.unhexlify(b"b1e1349120b6e832ef976f5d")
aad = binascii.unhexlify(b"b6d729aab8e6416d7002b9faa794c410d8d2f193")
encryptor = base.Cipher(
algorithms.AES(key), modes.GCM(iv), backend=backend
).encryptor()
encryptor.authenticate_additional_data(aad)
encryptor.finalize()
decryptor = base.Cipher(
algorithms.AES(key), modes.GCM(iv), backend=backend
).decryptor()
decryptor.authenticate_additional_data(aad)
with pytest.raises(ValueError):
decryptor.finalize()
def test_gcm_tag_decrypt_mode(self, backend):
key = binascii.unhexlify(b"5211242698bed4774a090620a6ca56f3")
iv = binascii.unhexlify(b"b1e1349120b6e832ef976f5d")
aad = binascii.unhexlify(b"b6d729aab8e6416d7002b9faa794c410d8d2f193")
encryptor = base.Cipher(
algorithms.AES(key), modes.GCM(iv), backend=backend
).encryptor()
encryptor.authenticate_additional_data(aad)
encryptor.finalize()
tag = encryptor.tag
decryptor = base.Cipher(
algorithms.AES(key), modes.GCM(iv, tag), backend=backend
).decryptor()
decryptor.authenticate_additional_data(aad)
decryptor.finalize()
def test_gcm_tag_decrypt_finalize(self, backend):
key = binascii.unhexlify(b"5211242698bed4774a090620a6ca56f3")
iv = binascii.unhexlify(b"b1e1349120b6e832ef976f5d")
aad = binascii.unhexlify(b"b6d729aab8e6416d7002b9faa794c410d8d2f193")
encryptor = base.Cipher(
algorithms.AES(key), modes.GCM(iv), backend=backend
).encryptor()
encryptor.authenticate_additional_data(aad)
encryptor.finalize()
tag = encryptor.tag
decryptor = base.Cipher(
algorithms.AES(key), modes.GCM(iv), backend=backend
).decryptor()
decryptor.authenticate_additional_data(aad)
decryptor.finalize_with_tag(tag)
@pytest.mark.parametrize("tag", [b"tagtooshort", b"toolong" * 12])
def test_gcm_tag_decrypt_finalize_tag_length(self, tag, backend):
decryptor = base.Cipher(
algorithms.AES(b"0" * 16), modes.GCM(b"0" * 12), backend=backend
).decryptor()
with pytest.raises(ValueError):
decryptor.finalize_with_tag(tag)
def test_buffer_protocol(self, backend):
data = bytearray(b"helloworld")
enc = base.Cipher(
algorithms.AES(bytearray(b"\x00" * 16)),
modes.GCM(bytearray(b"\x00" * 12)),
backend,
).encryptor()
enc.authenticate_additional_data(bytearray(b"foo"))
ct = enc.update(data) + enc.finalize()
dec = base.Cipher(
algorithms.AES(bytearray(b"\x00" * 16)),
modes.GCM(bytearray(b"\x00" * 12), enc.tag),
backend,
).decryptor()
dec.authenticate_additional_data(bytearray(b"foo"))
pt = dec.update(ct) + dec.finalize()
assert pt == data
@pytest.mark.parametrize("size", [8, 128])
def test_gcm_min_max_iv(self, size, backend):
if backend._fips_enabled:
# Red Hat disables non-96-bit IV support as part of its FIPS
# patches.
pytest.skip("Non-96-bit IVs unsupported in FIPS mode.")
key = os.urandom(16)
iv = b"\x00" * size
payload = b"data"
encryptor = base.Cipher(algorithms.AES(key), modes.GCM(iv)).encryptor()
ct = encryptor.update(payload)
encryptor.finalize()
tag = encryptor.tag
decryptor = base.Cipher(algorithms.AES(key), modes.GCM(iv)).decryptor()
pt = decryptor.update(ct)
decryptor.finalize_with_tag(tag)
assert pt == payload
@pytest.mark.parametrize("alg", [algorithms.AES128, algorithms.AES256])
def test_alternate_aes_classes(self, alg, backend):
data = bytearray(b"sixteen_byte_msg")
cipher = base.Cipher(
alg(b"0" * (alg.key_size // 8)), modes.GCM(b"\x00" * 12), backend
)
enc = cipher.encryptor()
ct = enc.update(data) + enc.finalize()
dec = cipher.decryptor()
pt = dec.update(ct) + dec.finalize_with_tag(enc.tag)
assert pt == data
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