# 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.

from __future__ import absolute_import, division, print_function

import binascii
import os

import pytest

from cryptography.hazmat.backends.interfaces import CipherBackend
from cryptography.hazmat.primitives.ciphers import algorithms, base, modes

from .utils import _load_all_params, generate_aead_test, generate_encrypt_test
from ...doubles import DummyMode
from ...utils import load_nist_vectors


@pytest.mark.supported(
    only_if=lambda backend: backend.cipher_supported(
        algorithms.AES(b"\x00" * 32), modes.XTS(b"\x00" * 16)
    ),
    skip_message="Does not support AES XTS",
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestAESModeXTS(object):
    @pytest.mark.parametrize(
        "vector",
        # This list comprehension excludes any vector that does not have a
        # data unit length that is divisible by 8. The NIST vectors include
        # tests for implementations that support encryption of data that is
        # not divisible modulo 8, but OpenSSL is not such an implementation.
        [x for x in _load_all_params(
            os.path.join("ciphers", "AES", "XTS", "tweak-128hexstr"),
            ["XTSGenAES128.rsp", "XTSGenAES256.rsp"],
            load_nist_vectors
        ) if int(x["dataunitlen"]) / 8.0 == int(x["dataunitlen"]) // 8]
    )
    def test_xts_vectors(self, vector, backend):
        key = binascii.unhexlify(vector["key"])
        tweak = binascii.unhexlify(vector["i"])
        pt = binascii.unhexlify(vector["pt"])
        ct = binascii.unhexlify(vector["ct"])
        cipher = base.Cipher(algorithms.AES(key), modes.XTS(tweak), backend)
        enc = cipher.encryptor()
        computed_ct = enc.update(pt) + enc.finalize()
        assert computed_ct == ct
        dec = cipher.decryptor()
        computed_pt = dec.update(ct) + dec.finalize()
        assert computed_pt == pt


@pytest.mark.supported(
    only_if=lambda backend: backend.cipher_supported(
        algorithms.AES(b"\x00" * 16), modes.CBC(b"\x00" * 16)
    ),
    skip_message="Does not support AES CBC",
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestAESModeCBC(object):
    test_cbc = generate_encrypt_test(
        load_nist_vectors,
        os.path.join("ciphers", "AES", "CBC"),
        [
            "CBCGFSbox128.rsp",
            "CBCGFSbox192.rsp",
            "CBCGFSbox256.rsp",
            "CBCKeySbox128.rsp",
            "CBCKeySbox192.rsp",
            "CBCKeySbox256.rsp",
            "CBCVarKey128.rsp",
            "CBCVarKey192.rsp",
            "CBCVarKey256.rsp",
            "CBCVarTxt128.rsp",
            "CBCVarTxt192.rsp",
            "CBCVarTxt256.rsp",
            "CBCMMT128.rsp",
            "CBCMMT192.rsp",
            "CBCMMT256.rsp",
        ],
        lambda key, **kwargs: algorithms.AES(binascii.unhexlify(key)),
        lambda iv, **kwargs: modes.CBC(binascii.unhexlify(iv)),
    )


@pytest.mark.supported(
    only_if=lambda backend: backend.cipher_supported(
        algorithms.AES(b"\x00" * 16), modes.ECB()
    ),
    skip_message="Does not support AES ECB",
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestAESModeECB(object):
    test_ecb = generate_encrypt_test(
        load_nist_vectors,
        os.path.join("ciphers", "AES", "ECB"),
        [
            "ECBGFSbox128.rsp",
            "ECBGFSbox192.rsp",
            "ECBGFSbox256.rsp",
            "ECBKeySbox128.rsp",
            "ECBKeySbox192.rsp",
            "ECBKeySbox256.rsp",
            "ECBVarKey128.rsp",
            "ECBVarKey192.rsp",
            "ECBVarKey256.rsp",
            "ECBVarTxt128.rsp",
            "ECBVarTxt192.rsp",
            "ECBVarTxt256.rsp",
            "ECBMMT128.rsp",
            "ECBMMT192.rsp",
            "ECBMMT256.rsp",
        ],
        lambda key, **kwargs: algorithms.AES(binascii.unhexlify(key)),
        lambda **kwargs: modes.ECB(),
    )


@pytest.mark.supported(
    only_if=lambda backend: backend.cipher_supported(
        algorithms.AES(b"\x00" * 16), modes.OFB(b"\x00" * 16)
    ),
    skip_message="Does not support AES OFB",
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestAESModeOFB(object):
    test_ofb = generate_encrypt_test(
        load_nist_vectors,
        os.path.join("ciphers", "AES", "OFB"),
        [
            "OFBGFSbox128.rsp",
            "OFBGFSbox192.rsp",
            "OFBGFSbox256.rsp",
            "OFBKeySbox128.rsp",
            "OFBKeySbox192.rsp",
            "OFBKeySbox256.rsp",
            "OFBVarKey128.rsp",
            "OFBVarKey192.rsp",
            "OFBVarKey256.rsp",
            "OFBVarTxt128.rsp",
            "OFBVarTxt192.rsp",
            "OFBVarTxt256.rsp",
            "OFBMMT128.rsp",
            "OFBMMT192.rsp",
            "OFBMMT256.rsp",
        ],
        lambda key, **kwargs: algorithms.AES(binascii.unhexlify(key)),
        lambda iv, **kwargs: modes.OFB(binascii.unhexlify(iv)),
    )


@pytest.mark.supported(
    only_if=lambda backend: backend.cipher_supported(
        algorithms.AES(b"\x00" * 16), modes.CFB(b"\x00" * 16)
    ),
    skip_message="Does not support AES CFB",
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestAESModeCFB(object):
    test_cfb = generate_encrypt_test(
        load_nist_vectors,
        os.path.join("ciphers", "AES", "CFB"),
        [
            "CFB128GFSbox128.rsp",
            "CFB128GFSbox192.rsp",
            "CFB128GFSbox256.rsp",
            "CFB128KeySbox128.rsp",
            "CFB128KeySbox192.rsp",
            "CFB128KeySbox256.rsp",
            "CFB128VarKey128.rsp",
            "CFB128VarKey192.rsp",
            "CFB128VarKey256.rsp",
            "CFB128VarTxt128.rsp",
            "CFB128VarTxt192.rsp",
            "CFB128VarTxt256.rsp",
            "CFB128MMT128.rsp",
            "CFB128MMT192.rsp",
            "CFB128MMT256.rsp",
        ],
        lambda key, **kwargs: algorithms.AES(binascii.unhexlify(key)),
        lambda iv, **kwargs: modes.CFB(binascii.unhexlify(iv)),
    )


@pytest.mark.supported(
    only_if=lambda backend: backend.cipher_supported(
        algorithms.AES(b"\x00" * 16), modes.CFB8(b"\x00" * 16)
    ),
    skip_message="Does not support AES CFB8",
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestAESModeCFB8(object):
    test_cfb8 = generate_encrypt_test(
        load_nist_vectors,
        os.path.join("ciphers", "AES", "CFB"),
        [
            "CFB8GFSbox128.rsp",
            "CFB8GFSbox192.rsp",
            "CFB8GFSbox256.rsp",
            "CFB8KeySbox128.rsp",
            "CFB8KeySbox192.rsp",
            "CFB8KeySbox256.rsp",
            "CFB8VarKey128.rsp",
            "CFB8VarKey192.rsp",
            "CFB8VarKey256.rsp",
            "CFB8VarTxt128.rsp",
            "CFB8VarTxt192.rsp",
            "CFB8VarTxt256.rsp",
            "CFB8MMT128.rsp",
            "CFB8MMT192.rsp",
            "CFB8MMT256.rsp",
        ],
        lambda key, **kwargs: algorithms.AES(binascii.unhexlify(key)),
        lambda iv, **kwargs: modes.CFB8(binascii.unhexlify(iv)),
    )


@pytest.mark.supported(
    only_if=lambda backend: backend.cipher_supported(
        algorithms.AES(b"\x00" * 16), modes.CTR(b"\x00" * 16)
    ),
    skip_message="Does not support AES CTR",
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestAESModeCTR(object):
    test_ctr = generate_encrypt_test(
        load_nist_vectors,
        os.path.join("ciphers", "AES", "CTR"),
        ["aes-128-ctr.txt", "aes-192-ctr.txt", "aes-256-ctr.txt"],
        lambda key, **kwargs: algorithms.AES(binascii.unhexlify(key)),
        lambda iv, **kwargs: modes.CTR(binascii.unhexlify(iv)),
    )


@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",
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
class TestAESModeGCM(object):
    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()
        encryptor._bytes_processed = modes.GCM._MAX_ENCRYPTED_BYTES - 16
        encryptor.update(b"0" * 16)
        assert (
            encryptor._bytes_processed == modes.GCM._MAX_ENCRYPTED_BYTES
        )
        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()
        encryptor._aad_bytes_processed = modes.GCM._MAX_AAD_BYTES - 16
        encryptor.authenticate_additional_data(b"0" * 16)
        assert encryptor._aad_bytes_processed == modes.GCM._MAX_AAD_BYTES
        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
        encryptor.update(b"0" * 7)
        assert encryptor._bytes_processed == 15
        encryptor.update(b"0" * 18)
        assert encryptor._bytes_processed == 33

    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
        encryptor.authenticate_additional_data(b"0" * 18)
        assert encryptor._aad_bytes_processed == 26

    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)

    def test_gcm_tag_decrypt_finalize_tag_length(self, 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(b"tagtooshort")

    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(
    "mode",
    [
        modes.CBC(bytearray(b"\x00" * 16)),
        modes.CTR(bytearray(b"\x00" * 16)),
        modes.OFB(bytearray(b"\x00" * 16)),
        modes.CFB(bytearray(b"\x00" * 16)),
        modes.CFB8(bytearray(b"\x00" * 16)),
        modes.XTS(bytearray(b"\x00" * 16)),
        # Add a dummy mode for coverage of the cipher_supported check.
        DummyMode(),
    ]
)
@pytest.mark.requires_backend_interface(interface=CipherBackend)
def test_buffer_protocol_alternate_modes(mode, backend):
    data = bytearray(b"sixteen_byte_msg")
    key = algorithms.AES(bytearray(os.urandom(32)))
    if not backend.cipher_supported(key, mode):
        pytest.skip("AES in {} mode not supported".format(mode.name))
    cipher = base.Cipher(key, mode, backend)
    enc = cipher.encryptor()
    ct = enc.update(data) + enc.finalize()
    dec = cipher.decryptor()
    pt = dec.update(ct) + dec.finalize()
    assert pt == data
