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Александр Геннадьевич Сальный
2022-10-15 21:01:12 +03:00
commit 7caeeaaff5
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venv/Lib/site-packages/cryptography/hazmat/backends/openssl/aead.py Normal file
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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 typing
from cryptography.exceptions import InvalidTag
if typing.TYPE_CHECKING:
from cryptography.hazmat.backends.openssl.backend import Backend
from cryptography.hazmat.primitives.ciphers.aead import (
AESCCM,
AESGCM,
AESOCB3,
AESSIV,
ChaCha20Poly1305,
)
_AEAD_TYPES = typing.Union[
AESCCM, AESGCM, AESOCB3, AESSIV, ChaCha20Poly1305
]
_ENCRYPT = 1
_DECRYPT = 0
def _aead_cipher_name(cipher: "_AEAD_TYPES") -> bytes:
from cryptography.hazmat.primitives.ciphers.aead import (
AESCCM,
AESGCM,
AESOCB3,
AESSIV,
ChaCha20Poly1305,
)
if isinstance(cipher, ChaCha20Poly1305):
return b"chacha20-poly1305"
elif isinstance(cipher, AESCCM):
return f"aes-{len(cipher._key) * 8}-ccm".encode("ascii")
elif isinstance(cipher, AESOCB3):
return f"aes-{len(cipher._key) * 8}-ocb".encode("ascii")
elif isinstance(cipher, AESSIV):
return f"aes-{len(cipher._key) * 8 // 2}-siv".encode("ascii")
else:
assert isinstance(cipher, AESGCM)
return f"aes-{len(cipher._key) * 8}-gcm".encode("ascii")
def _evp_cipher(cipher_name: bytes, backend: "Backend"):
if cipher_name.endswith(b"-siv"):
evp_cipher = backend._lib.EVP_CIPHER_fetch(
backend._ffi.NULL,
cipher_name,
backend._ffi.NULL,
)
backend.openssl_assert(evp_cipher != backend._ffi.NULL)
evp_cipher = backend._ffi.gc(evp_cipher, backend._lib.EVP_CIPHER_free)
else:
evp_cipher = backend._lib.EVP_get_cipherbyname(cipher_name)
backend.openssl_assert(evp_cipher != backend._ffi.NULL)
return evp_cipher
def _aead_setup(
backend: "Backend",
cipher_name: bytes,
key: bytes,
nonce: bytes,
tag: typing.Optional[bytes],
tag_len: int,
operation: int,
):
evp_cipher = _evp_cipher(cipher_name, backend)
ctx = backend._lib.EVP_CIPHER_CTX_new()
ctx = backend._ffi.gc(ctx, backend._lib.EVP_CIPHER_CTX_free)
res = backend._lib.EVP_CipherInit_ex(
ctx,
evp_cipher,
backend._ffi.NULL,
backend._ffi.NULL,
backend._ffi.NULL,
int(operation == _ENCRYPT),
)
backend.openssl_assert(res != 0)
res = backend._lib.EVP_CIPHER_CTX_set_key_length(ctx, len(key))
backend.openssl_assert(res != 0)
res = backend._lib.EVP_CIPHER_CTX_ctrl(
ctx,
backend._lib.EVP_CTRL_AEAD_SET_IVLEN,
len(nonce),
backend._ffi.NULL,
)
backend.openssl_assert(res != 0)
if operation == _DECRYPT:
assert tag is not None
res = backend._lib.EVP_CIPHER_CTX_ctrl(
ctx, backend._lib.EVP_CTRL_AEAD_SET_TAG, len(tag), tag
)
backend.openssl_assert(res != 0)
elif cipher_name.endswith(b"-ccm"):
res = backend._lib.EVP_CIPHER_CTX_ctrl(
ctx, backend._lib.EVP_CTRL_AEAD_SET_TAG, tag_len, backend._ffi.NULL
)
backend.openssl_assert(res != 0)
nonce_ptr = backend._ffi.from_buffer(nonce)
key_ptr = backend._ffi.from_buffer(key)
res = backend._lib.EVP_CipherInit_ex(
ctx,
backend._ffi.NULL,
backend._ffi.NULL,
key_ptr,
nonce_ptr,
int(operation == _ENCRYPT),
)
backend.openssl_assert(res != 0)
return ctx
def _set_length(backend: "Backend", ctx, data_len: int) -> None:
intptr = backend._ffi.new("int *")
res = backend._lib.EVP_CipherUpdate(
ctx, backend._ffi.NULL, intptr, backend._ffi.NULL, data_len
)
backend.openssl_assert(res != 0)
def _process_aad(backend: "Backend", ctx, associated_data: bytes) -> None:
outlen = backend._ffi.new("int *")
res = backend._lib.EVP_CipherUpdate(
ctx, backend._ffi.NULL, outlen, associated_data, len(associated_data)
)
backend.openssl_assert(res != 0)
def _process_data(backend: "Backend", ctx, data: bytes) -> bytes:
outlen = backend._ffi.new("int *")
buf = backend._ffi.new("unsigned char[]", len(data))
res = backend._lib.EVP_CipherUpdate(ctx, buf, outlen, data, len(data))
if res == 0:
# AES SIV can error here if the data is invalid on decrypt
backend._consume_errors()
raise InvalidTag
return backend._ffi.buffer(buf, outlen[0])[:]
def _encrypt(
backend: "Backend",
cipher: "_AEAD_TYPES",
nonce: bytes,
data: bytes,
associated_data: typing.List[bytes],
tag_length: int,
) -> bytes:
from cryptography.hazmat.primitives.ciphers.aead import AESCCM, AESSIV
cipher_name = _aead_cipher_name(cipher)
ctx = _aead_setup(
backend, cipher_name, cipher._key, nonce, None, tag_length, _ENCRYPT
)
# CCM requires us to pass the length of the data before processing anything
# However calling this with any other AEAD results in an error
if isinstance(cipher, AESCCM):
_set_length(backend, ctx, len(data))
for ad in associated_data:
_process_aad(backend, ctx, ad)
processed_data = _process_data(backend, ctx, data)
outlen = backend._ffi.new("int *")
# All AEADs we support besides OCB are streaming so they return nothing
# in finalization. OCB can return up to (16 byte block - 1) bytes so
# we need a buffer here too.
buf = backend._ffi.new("unsigned char[]", 16)
res = backend._lib.EVP_CipherFinal_ex(ctx, buf, outlen)
backend.openssl_assert(res != 0)
processed_data += backend._ffi.buffer(buf, outlen[0])[:]
tag_buf = backend._ffi.new("unsigned char[]", tag_length)
res = backend._lib.EVP_CIPHER_CTX_ctrl(
ctx, backend._lib.EVP_CTRL_AEAD_GET_TAG, tag_length, tag_buf
)
backend.openssl_assert(res != 0)
tag = backend._ffi.buffer(tag_buf)[:]
if isinstance(cipher, AESSIV):
# RFC 5297 defines the output as IV || C, where the tag we generate is
# the "IV" and C is the ciphertext. This is the opposite of our
# other AEADs, which are Ciphertext || Tag
backend.openssl_assert(len(tag) == 16)
return tag + processed_data
else:
return processed_data + tag
def _decrypt(
backend: "Backend",
cipher: "_AEAD_TYPES",
nonce: bytes,
data: bytes,
associated_data: typing.List[bytes],
tag_length: int,
) -> bytes:
from cryptography.hazmat.primitives.ciphers.aead import AESCCM, AESSIV
if len(data) < tag_length:
raise InvalidTag
if isinstance(cipher, AESSIV):
# RFC 5297 defines the output as IV || C, where the tag we generate is
# the "IV" and C is the ciphertext. This is the opposite of our
# other AEADs, which are Ciphertext || Tag
tag = data[:tag_length]
data = data[tag_length:]
else:
tag = data[-tag_length:]
data = data[:-tag_length]
cipher_name = _aead_cipher_name(cipher)
ctx = _aead_setup(
backend, cipher_name, cipher._key, nonce, tag, tag_length, _DECRYPT
)
# CCM requires us to pass the length of the data before processing anything
# However calling this with any other AEAD results in an error
if isinstance(cipher, AESCCM):
_set_length(backend, ctx, len(data))
for ad in associated_data:
_process_aad(backend, ctx, ad)
# CCM has a different error path if the tag doesn't match. Errors are
# raised in Update and Final is irrelevant.
if isinstance(cipher, AESCCM):
outlen = backend._ffi.new("int *")
buf = backend._ffi.new("unsigned char[]", len(data))
res = backend._lib.EVP_CipherUpdate(ctx, buf, outlen, data, len(data))
if res != 1:
backend._consume_errors()
raise InvalidTag
processed_data = backend._ffi.buffer(buf, outlen[0])[:]
else:
processed_data = _process_data(backend, ctx, data)
outlen = backend._ffi.new("int *")
# OCB can return up to 15 bytes (16 byte block - 1) in finalization
buf = backend._ffi.new("unsigned char[]", 16)
res = backend._lib.EVP_CipherFinal_ex(ctx, buf, outlen)
processed_data += backend._ffi.buffer(buf, outlen[0])[:]
if res == 0:
backend._consume_errors()
raise InvalidTag
return processed_data