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|
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import absolute_import, division, print_function
import collections
import itertools
import math
import six
from cryptography import utils
from cryptography.exceptions import (
AlreadyFinalized, InternalError, InvalidSignature, InvalidTag,
UnsupportedAlgorithm, _Reasons
)
from cryptography.hazmat.backends.interfaces import (
CMACBackend, CipherBackend, DSABackend, HMACBackend, HashBackend,
PBKDF2HMACBackend, RSABackend
)
from cryptography.hazmat.bindings.openssl.binding import Binding
from cryptography.hazmat.primitives import hashes, interfaces
from cryptography.hazmat.primitives.asymmetric import dsa, rsa
from cryptography.hazmat.primitives.asymmetric.padding import (
MGF1, PKCS1v15, PSS
)
from cryptography.hazmat.primitives.ciphers.algorithms import (
AES, ARC4, Blowfish, CAST5, Camellia, IDEA, SEED, TripleDES
)
from cryptography.hazmat.primitives.ciphers.modes import (
CBC, CFB, CTR, ECB, GCM, OFB
)
_OpenSSLError = collections.namedtuple("_OpenSSLError",
["code", "lib", "func", "reason"])
@utils.register_interface(CipherBackend)
@utils.register_interface(CMACBackend)
@utils.register_interface(DSABackend)
@utils.register_interface(HashBackend)
@utils.register_interface(HMACBackend)
@utils.register_interface(PBKDF2HMACBackend)
@utils.register_interface(RSABackend)
class Backend(object):
"""
OpenSSL API binding interfaces.
"""
name = "openssl"
def __init__(self):
self._binding = Binding()
self._ffi = self._binding.ffi
self._lib = self._binding.lib
self._binding.init_static_locks()
# adds all ciphers/digests for EVP
self._lib.OpenSSL_add_all_algorithms()
# registers available SSL/TLS ciphers and digests
self._lib.SSL_library_init()
# loads error strings for libcrypto and libssl functions
self._lib.SSL_load_error_strings()
self._cipher_registry = {}
self._register_default_ciphers()
self.activate_osrandom_engine()
def activate_builtin_random(self):
# Obtain a new structural reference.
e = self._lib.ENGINE_get_default_RAND()
if e != self._ffi.NULL:
self._lib.ENGINE_unregister_RAND(e)
# Reset the RNG to use the new engine.
self._lib.RAND_cleanup()
# decrement the structural reference from get_default_RAND
res = self._lib.ENGINE_finish(e)
assert res == 1
def activate_osrandom_engine(self):
# Unregister and free the current engine.
self.activate_builtin_random()
# Fetches an engine by id and returns it. This creates a structural
# reference.
e = self._lib.ENGINE_by_id(self._lib.Cryptography_osrandom_engine_id)
assert e != self._ffi.NULL
# Initialize the engine for use. This adds a functional reference.
res = self._lib.ENGINE_init(e)
assert res == 1
# Set the engine as the default RAND provider.
res = self._lib.ENGINE_set_default_RAND(e)
assert res == 1
# Decrement the structural ref incremented by ENGINE_by_id.
res = self._lib.ENGINE_free(e)
assert res == 1
# Decrement the functional ref incremented by ENGINE_init.
res = self._lib.ENGINE_finish(e)
assert res == 1
# Reset the RNG to use the new engine.
self._lib.RAND_cleanup()
def openssl_version_text(self):
"""
Friendly string name of linked OpenSSL.
Example: OpenSSL 1.0.1e 11 Feb 2013
"""
return self._ffi.string(self._lib.OPENSSL_VERSION_TEXT).decode("ascii")
def create_hmac_ctx(self, key, algorithm):
return _HMACContext(self, key, algorithm)
def hash_supported(self, algorithm):
digest = self._lib.EVP_get_digestbyname(algorithm.name.encode("ascii"))
return digest != self._ffi.NULL
def hmac_supported(self, algorithm):
return self.hash_supported(algorithm)
def create_hash_ctx(self, algorithm):
return _HashContext(self, algorithm)
def cipher_supported(self, cipher, mode):
try:
adapter = self._cipher_registry[type(cipher), type(mode)]
except KeyError:
return False
evp_cipher = adapter(self, cipher, mode)
return self._ffi.NULL != evp_cipher
def register_cipher_adapter(self, cipher_cls, mode_cls, adapter):
if (cipher_cls, mode_cls) in self._cipher_registry:
raise ValueError("Duplicate registration for: {0} {1}".format(
cipher_cls, mode_cls)
)
self._cipher_registry[cipher_cls, mode_cls] = adapter
def _register_default_ciphers(self):
for cipher_cls, mode_cls in itertools.product(
[AES, Camellia],
[CBC, CTR, ECB, OFB, CFB],
):
self.register_cipher_adapter(
cipher_cls,
mode_cls,
GetCipherByName("{cipher.name}-{cipher.key_size}-{mode.name}")
)
for mode_cls in [CBC, CFB, OFB]:
self.register_cipher_adapter(
TripleDES,
mode_cls,
GetCipherByName("des-ede3-{mode.name}")
)
for mode_cls in [CBC, CFB, OFB, ECB]:
self.register_cipher_adapter(
Blowfish,
mode_cls,
GetCipherByName("bf-{mode.name}")
)
for mode_cls in [CBC, CFB, OFB, ECB]:
self.register_cipher_adapter(
SEED,
mode_cls,
GetCipherByName("seed-{mode.name}")
)
for cipher_cls, mode_cls in itertools.product(
[CAST5, IDEA],
[CBC, OFB, CFB, ECB],
):
self.register_cipher_adapter(
cipher_cls,
mode_cls,
GetCipherByName("{cipher.name}-{mode.name}")
)
self.register_cipher_adapter(
ARC4,
type(None),
GetCipherByName("rc4")
)
self.register_cipher_adapter(
AES,
GCM,
GetCipherByName("{cipher.name}-{cipher.key_size}-{mode.name}")
)
def create_symmetric_encryption_ctx(self, cipher, mode):
return _CipherContext(self, cipher, mode, _CipherContext._ENCRYPT)
def create_symmetric_decryption_ctx(self, cipher, mode):
return _CipherContext(self, cipher, mode, _CipherContext._DECRYPT)
def pbkdf2_hmac_supported(self, algorithm):
if self._lib.Cryptography_HAS_PBKDF2_HMAC:
return self.hmac_supported(algorithm)
else:
# OpenSSL < 1.0.0 has an explicit PBKDF2-HMAC-SHA1 function,
# so if the PBKDF2_HMAC function is missing we only support
# SHA1 via PBKDF2_HMAC_SHA1.
return isinstance(algorithm, hashes.SHA1)
def derive_pbkdf2_hmac(self, algorithm, length, salt, iterations,
key_material):
buf = self._ffi.new("char[]", length)
if self._lib.Cryptography_HAS_PBKDF2_HMAC:
evp_md = self._lib.EVP_get_digestbyname(
algorithm.name.encode("ascii"))
assert evp_md != self._ffi.NULL
res = self._lib.PKCS5_PBKDF2_HMAC(
key_material,
len(key_material),
salt,
len(salt),
iterations,
evp_md,
length,
buf
)
assert res == 1
else:
if not isinstance(algorithm, hashes.SHA1):
raise UnsupportedAlgorithm(
"This version of OpenSSL only supports PBKDF2HMAC with "
"SHA1",
_Reasons.UNSUPPORTED_HASH
)
res = self._lib.PKCS5_PBKDF2_HMAC_SHA1(
key_material,
len(key_material),
salt,
len(salt),
iterations,
length,
buf
)
assert res == 1
return self._ffi.buffer(buf)[:]
def _err_string(self, code):
err_buf = self._ffi.new("char[]", 256)
self._lib.ERR_error_string_n(code, err_buf, 256)
return self._ffi.string(err_buf, 256)[:]
def _consume_errors(self):
errors = []
while True:
code = self._lib.ERR_get_error()
if code == 0:
break
lib = self._lib.ERR_GET_LIB(code)
func = self._lib.ERR_GET_FUNC(code)
reason = self._lib.ERR_GET_REASON(code)
errors.append(_OpenSSLError(code, lib, func, reason))
return errors
def _unknown_error(self, error):
return InternalError(
"Unknown error code {0} from OpenSSL, "
"you should probably file a bug. {1}".format(
error.code, self._err_string(error.code)
)
)
def _bn_to_int(self, bn):
if six.PY3:
# Python 3 has constant time from_bytes, so use that.
bn_num_bytes = (self._lib.BN_num_bits(bn) + 7) // 8
bin_ptr = self._ffi.new("unsigned char[]", bn_num_bytes)
bin_len = self._lib.BN_bn2bin(bn, bin_ptr)
assert bin_len > 0
assert bin_ptr != self._ffi.NULL
return int.from_bytes(self._ffi.buffer(bin_ptr)[:bin_len], "big")
else:
# Under Python 2 the best we can do is hex()
hex_cdata = self._lib.BN_bn2hex(bn)
assert hex_cdata != self._ffi.NULL
hex_str = self._ffi.string(hex_cdata)
self._lib.OPENSSL_free(hex_cdata)
return int(hex_str, 16)
def _int_to_bn(self, num, bn=None):
"""
Converts a python integer to a BIGNUM. The returned BIGNUM will not
be garbage collected (to support adding them to structs that take
ownership of the object). Be sure to register it for GC if it will
be discarded after use.
"""
if bn is None:
bn = self._ffi.NULL
if six.PY3:
# Python 3 has constant time to_bytes, so use that.
binary = num.to_bytes(int(num.bit_length() / 8.0 + 1), "big")
bn_ptr = self._lib.BN_bin2bn(binary, len(binary), bn)
assert bn_ptr != self._ffi.NULL
return bn_ptr
else:
# Under Python 2 the best we can do is hex()
hex_num = hex(num).rstrip("L").lstrip("0x").encode("ascii") or b"0"
bn_ptr = self._ffi.new("BIGNUM **")
bn_ptr[0] = bn
res = self._lib.BN_hex2bn(bn_ptr, hex_num)
assert res != 0
assert bn_ptr[0] != self._ffi.NULL
return bn_ptr[0]
def generate_rsa_private_key(self, public_exponent, key_size):
if public_exponent < 3:
raise ValueError("public_exponent must be >= 3")
if public_exponent & 1 == 0:
raise ValueError("public_exponent must be odd")
if key_size < 512:
raise ValueError("key_size must be at least 512-bits")
ctx = self._lib.RSA_new()
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.RSA_free)
bn = self._int_to_bn(public_exponent)
bn = self._ffi.gc(bn, self._lib.BN_free)
res = self._lib.RSA_generate_key_ex(
ctx, key_size, bn, self._ffi.NULL
)
assert res == 1
return self._rsa_cdata_to_private_key(ctx)
def _new_evp_pkey(self):
evp_pkey = self._lib.EVP_PKEY_new()
assert evp_pkey != self._ffi.NULL
return self._ffi.gc(evp_pkey, backend._lib.EVP_PKEY_free)
def _rsa_private_key_to_evp_pkey(self, private_key):
evp_pkey = self._new_evp_pkey()
rsa_cdata = self._rsa_cdata_from_private_key(private_key)
res = self._lib.EVP_PKEY_assign_RSA(evp_pkey, rsa_cdata)
assert res == 1
return evp_pkey
def _rsa_public_key_to_evp_pkey(self, public_key):
evp_pkey = self._new_evp_pkey()
rsa_cdata = self._rsa_cdata_from_public_key(public_key)
res = self._lib.EVP_PKEY_assign_RSA(evp_pkey, rsa_cdata)
assert res == 1
return evp_pkey
def _rsa_cdata_to_private_key(self, cdata):
return rsa.RSAPrivateKey(
p=self._bn_to_int(cdata.p),
q=self._bn_to_int(cdata.q),
dmp1=self._bn_to_int(cdata.dmp1),
dmq1=self._bn_to_int(cdata.dmq1),
iqmp=self._bn_to_int(cdata.iqmp),
private_exponent=self._bn_to_int(cdata.d),
public_exponent=self._bn_to_int(cdata.e),
modulus=self._bn_to_int(cdata.n),
)
def _rsa_cdata_from_private_key(self, private_key):
# Does not GC the RSA cdata. You *must* make sure it's freed
# correctly yourself!
ctx = self._lib.RSA_new()
assert ctx != self._ffi.NULL
ctx.p = self._int_to_bn(private_key.p)
ctx.q = self._int_to_bn(private_key.q)
ctx.d = self._int_to_bn(private_key.d)
ctx.e = self._int_to_bn(private_key.e)
ctx.n = self._int_to_bn(private_key.n)
ctx.dmp1 = self._int_to_bn(private_key.dmp1)
ctx.dmq1 = self._int_to_bn(private_key.dmq1)
ctx.iqmp = self._int_to_bn(private_key.iqmp)
res = self._lib.RSA_blinding_on(ctx, self._ffi.NULL)
assert res == 1
return ctx
def _rsa_cdata_from_public_key(self, public_key):
# Does not GC the RSA cdata. You *must* make sure it's freed
# correctly yourself!
ctx = self._lib.RSA_new()
assert ctx != self._ffi.NULL
ctx.e = self._int_to_bn(public_key.e)
ctx.n = self._int_to_bn(public_key.n)
res = self._lib.RSA_blinding_on(ctx, self._ffi.NULL)
assert res == 1
return ctx
def create_rsa_signature_ctx(self, private_key, padding, algorithm):
return _RSASignatureContext(self, private_key, padding, algorithm)
def create_rsa_verification_ctx(self, public_key, signature, padding,
algorithm):
return _RSAVerificationContext(self, public_key, signature, padding,
algorithm)
def mgf1_hash_supported(self, algorithm):
if self._lib.Cryptography_HAS_MGF1_MD:
return self.hash_supported(algorithm)
else:
return isinstance(algorithm, hashes.SHA1)
def generate_dsa_parameters(self, key_size):
if key_size not in (1024, 2048, 3072):
raise ValueError(
"Key size must be 1024 or 2048 or 3072 bits")
if (self._lib.OPENSSL_VERSION_NUMBER < 0x1000000f and
key_size > 1024):
raise ValueError(
"Key size must be 1024 because OpenSSL < 1.0.0 doesn't "
"support larger key sizes")
ctx = self._lib.DSA_new()
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.DSA_free)
res = self._lib.DSA_generate_parameters_ex(
ctx, key_size, self._ffi.NULL, 0,
self._ffi.NULL, self._ffi.NULL, self._ffi.NULL
)
assert res == 1
return dsa.DSAParameters(
modulus=self._bn_to_int(ctx.p),
subgroup_order=self._bn_to_int(ctx.q),
generator=self._bn_to_int(ctx.g)
)
def generate_dsa_private_key(self, parameters):
ctx = self._lib.DSA_new()
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.DSA_free)
ctx.p = self._int_to_bn(parameters.p)
ctx.q = self._int_to_bn(parameters.q)
ctx.g = self._int_to_bn(parameters.g)
self._lib.DSA_generate_key(ctx)
return dsa.DSAPrivateKey(
modulus=self._bn_to_int(ctx.p),
subgroup_order=self._bn_to_int(ctx.q),
generator=self._bn_to_int(ctx.g),
x=self._bn_to_int(ctx.priv_key),
y=self._bn_to_int(ctx.pub_key)
)
def decrypt_rsa(self, private_key, ciphertext, padding):
if isinstance(padding, PKCS1v15):
padding_enum = self._lib.RSA_PKCS1_PADDING
else:
raise UnsupportedAlgorithm(
"{0} is not supported by this backend".format(
padding.name
),
_Reasons.UNSUPPORTED_PADDING
)
key_size_bytes = int(math.ceil(private_key.key_size / 8.0))
if key_size_bytes < len(ciphertext):
raise ValueError("Ciphertext too large for key size")
if self._lib.Cryptography_HAS_PKEY_CTX:
return self._decrypt_rsa_pkey_ctx(private_key, ciphertext,
padding_enum)
else:
return self._decrypt_rsa_098(private_key, ciphertext, padding_enum)
def _decrypt_rsa_pkey_ctx(self, private_key, ciphertext, padding_enum):
evp_pkey = self._rsa_private_key_to_evp_pkey(private_key)
pkey_ctx = self._lib.EVP_PKEY_CTX_new(
evp_pkey, self._ffi.NULL
)
assert pkey_ctx != self._ffi.NULL
pkey_ctx = self._ffi.gc(pkey_ctx, self._lib.EVP_PKEY_CTX_free)
res = self._lib.EVP_PKEY_decrypt_init(pkey_ctx)
assert res == 1
res = self._lib.EVP_PKEY_CTX_set_rsa_padding(
pkey_ctx, padding_enum)
assert res > 0
buf_size = self._lib.EVP_PKEY_size(evp_pkey)
assert buf_size > 0
outlen = self._ffi.new("size_t *", buf_size)
buf = self._ffi.new("char[]", buf_size)
res = self._lib.Cryptography_EVP_PKEY_decrypt(
pkey_ctx,
buf,
outlen,
ciphertext,
len(ciphertext)
)
if res <= 0:
errors = self._consume_errors()
assert errors
assert errors[0].lib == self._lib.ERR_LIB_RSA
assert (
errors[0].reason == self._lib.RSA_R_BLOCK_TYPE_IS_NOT_01 or
errors[0].reason == self._lib.RSA_R_BLOCK_TYPE_IS_NOT_02
)
raise ValueError("Decryption failed")
return self._ffi.buffer(buf)[:outlen[0]]
def _decrypt_rsa_098(self, private_key, ciphertext, padding_enum):
rsa_cdata = self._rsa_cdata_from_private_key(private_key)
rsa_cdata = self._ffi.gc(rsa_cdata, self._lib.RSA_free)
key_size = self._lib.RSA_size(rsa_cdata)
assert key_size > 0
buf = self._ffi.new("unsigned char[]", key_size)
res = self._lib.RSA_private_decrypt(
len(ciphertext),
ciphertext,
buf,
rsa_cdata,
padding_enum
)
if res < 0:
errors = self._consume_errors()
assert errors
assert errors[0].lib == self._lib.ERR_LIB_RSA
assert (
errors[0].reason == self._lib.RSA_R_BLOCK_TYPE_IS_NOT_01 or
errors[0].reason == self._lib.RSA_R_BLOCK_TYPE_IS_NOT_02
)
raise ValueError("Decryption failed")
return self._ffi.buffer(buf)[:res]
def cmac_algorithm_supported(self, algorithm):
return (
backend._lib.Cryptography_HAS_CMAC == 1
and backend.cipher_supported(algorithm, CBC(
b"\x00" * algorithm.block_size))
)
def create_cmac_ctx(self, algorithm):
return _CMACContext(self, algorithm)
class GetCipherByName(object):
def __init__(self, fmt):
self._fmt = fmt
def __call__(self, backend, cipher, mode):
cipher_name = self._fmt.format(cipher=cipher, mode=mode).lower()
return backend._lib.EVP_get_cipherbyname(cipher_name.encode("ascii"))
@utils.register_interface(interfaces.CipherContext)
@utils.register_interface(interfaces.AEADCipherContext)
@utils.register_interface(interfaces.AEADEncryptionContext)
class _CipherContext(object):
_ENCRYPT = 1
_DECRYPT = 0
def __init__(self, backend, cipher, mode, operation):
self._backend = backend
self._cipher = cipher
self._mode = mode
self._operation = operation
self._tag = None
if isinstance(self._cipher, interfaces.BlockCipherAlgorithm):
self._block_size = self._cipher.block_size
else:
self._block_size = 1
ctx = self._backend._lib.EVP_CIPHER_CTX_new()
ctx = self._backend._ffi.gc(
ctx, self._backend._lib.EVP_CIPHER_CTX_free
)
registry = self._backend._cipher_registry
try:
adapter = registry[type(cipher), type(mode)]
except KeyError:
raise UnsupportedAlgorithm(
"cipher {0} in {1} mode is not supported "
"by this backend".format(
cipher.name, mode.name if mode else mode),
_Reasons.UNSUPPORTED_CIPHER
)
evp_cipher = adapter(self._backend, cipher, mode)
if evp_cipher == self._backend._ffi.NULL:
raise UnsupportedAlgorithm(
"cipher {0} in {1} mode is not supported "
"by this backend".format(
cipher.name, mode.name if mode else mode),
_Reasons.UNSUPPORTED_CIPHER
)
if isinstance(mode, interfaces.ModeWithInitializationVector):
iv_nonce = mode.initialization_vector
elif isinstance(mode, interfaces.ModeWithNonce):
iv_nonce = mode.nonce
else:
iv_nonce = self._backend._ffi.NULL
# begin init with cipher and operation type
res = self._backend._lib.EVP_CipherInit_ex(ctx, evp_cipher,
self._backend._ffi.NULL,
self._backend._ffi.NULL,
self._backend._ffi.NULL,
operation)
assert res != 0
# set the key length to handle variable key ciphers
res = self._backend._lib.EVP_CIPHER_CTX_set_key_length(
ctx, len(cipher.key)
)
assert res != 0
if isinstance(mode, GCM):
res = self._backend._lib.EVP_CIPHER_CTX_ctrl(
ctx, self._backend._lib.EVP_CTRL_GCM_SET_IVLEN,
len(iv_nonce), self._backend._ffi.NULL
)
assert res != 0
if operation == self._DECRYPT:
res = self._backend._lib.EVP_CIPHER_CTX_ctrl(
ctx, self._backend._lib.EVP_CTRL_GCM_SET_TAG,
len(mode.tag), mode.tag
)
assert res != 0
# pass key/iv
res = self._backend._lib.EVP_CipherInit_ex(
ctx,
self._backend._ffi.NULL,
self._backend._ffi.NULL,
cipher.key,
iv_nonce,
operation
)
assert res != 0
# We purposely disable padding here as it's handled higher up in the
# API.
self._backend._lib.EVP_CIPHER_CTX_set_padding(ctx, 0)
self._ctx = ctx
def update(self, data):
# OpenSSL 0.9.8e has an assertion in its EVP code that causes it
# to SIGABRT if you call update with an empty byte string. This can be
# removed when we drop support for 0.9.8e (CentOS/RHEL 5). This branch
# should be taken only when length is zero and mode is not GCM because
# AES GCM can return improper tag values if you don't call update
# with empty plaintext when authenticating AAD for ...reasons.
if len(data) == 0 and not isinstance(self._mode, GCM):
return b""
buf = self._backend._ffi.new("unsigned char[]",
len(data) + self._block_size - 1)
outlen = self._backend._ffi.new("int *")
res = self._backend._lib.EVP_CipherUpdate(self._ctx, buf, outlen, data,
len(data))
assert res != 0
return self._backend._ffi.buffer(buf)[:outlen[0]]
def finalize(self):
buf = self._backend._ffi.new("unsigned char[]", self._block_size)
outlen = self._backend._ffi.new("int *")
res = self._backend._lib.EVP_CipherFinal_ex(self._ctx, buf, outlen)
if res == 0:
errors = self._backend._consume_errors()
if not errors and isinstance(self._mode, GCM):
raise InvalidTag
assert errors
if errors[0][1:] == (
self._backend._lib.ERR_LIB_EVP,
self._backend._lib.EVP_F_EVP_ENCRYPTFINAL_EX,
self._backend._lib.EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH
) or errors[0][1:] == (
self._backend._lib.ERR_LIB_EVP,
self._backend._lib.EVP_F_EVP_DECRYPTFINAL_EX,
self._backend._lib.EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH
):
raise ValueError(
"The length of the provided data is not a multiple of "
"the block length."
)
else:
raise self._backend._unknown_error(errors[0])
if (isinstance(self._mode, GCM) and
self._operation == self._ENCRYPT):
block_byte_size = self._block_size // 8
tag_buf = self._backend._ffi.new(
"unsigned char[]", block_byte_size
)
res = self._backend._lib.EVP_CIPHER_CTX_ctrl(
self._ctx, self._backend._lib.EVP_CTRL_GCM_GET_TAG,
block_byte_size, tag_buf
)
assert res != 0
self._tag = self._backend._ffi.buffer(tag_buf)[:]
res = self._backend._lib.EVP_CIPHER_CTX_cleanup(self._ctx)
assert res == 1
return self._backend._ffi.buffer(buf)[:outlen[0]]
def authenticate_additional_data(self, data):
outlen = self._backend._ffi.new("int *")
res = self._backend._lib.EVP_CipherUpdate(
self._ctx, self._backend._ffi.NULL, outlen, data, len(data)
)
assert res != 0
@property
def tag(self):
return self._tag
@utils.register_interface(interfaces.HashContext)
class _HashContext(object):
def __init__(self, backend, algorithm, ctx=None):
self.algorithm = algorithm
self._backend = backend
if ctx is None:
ctx = self._backend._lib.EVP_MD_CTX_create()
ctx = self._backend._ffi.gc(ctx,
self._backend._lib.EVP_MD_CTX_destroy)
evp_md = self._backend._lib.EVP_get_digestbyname(
algorithm.name.encode("ascii"))
if evp_md == self._backend._ffi.NULL:
raise UnsupportedAlgorithm(
"{0} is not a supported hash on this backend".format(
algorithm.name),
_Reasons.UNSUPPORTED_HASH
)
res = self._backend._lib.EVP_DigestInit_ex(ctx, evp_md,
self._backend._ffi.NULL)
assert res != 0
self._ctx = ctx
def copy(self):
copied_ctx = self._backend._lib.EVP_MD_CTX_create()
copied_ctx = self._backend._ffi.gc(
copied_ctx, self._backend._lib.EVP_MD_CTX_destroy
)
res = self._backend._lib.EVP_MD_CTX_copy_ex(copied_ctx, self._ctx)
assert res != 0
return _HashContext(self._backend, self.algorithm, ctx=copied_ctx)
def update(self, data):
res = self._backend._lib.EVP_DigestUpdate(self._ctx, data, len(data))
assert res != 0
def finalize(self):
buf = self._backend._ffi.new("unsigned char[]",
self._backend._lib.EVP_MAX_MD_SIZE)
outlen = self._backend._ffi.new("unsigned int *")
res = self._backend._lib.EVP_DigestFinal_ex(self._ctx, buf, outlen)
assert res != 0
assert outlen[0] == self.algorithm.digest_size
res = self._backend._lib.EVP_MD_CTX_cleanup(self._ctx)
assert res == 1
return self._backend._ffi.buffer(buf)[:outlen[0]]
@utils.register_interface(interfaces.HashContext)
class _HMACContext(object):
def __init__(self, backend, key, algorithm, ctx=None):
self.algorithm = algorithm
self._backend = backend
if ctx is None:
ctx = self._backend._ffi.new("HMAC_CTX *")
self._backend._lib.HMAC_CTX_init(ctx)
ctx = self._backend._ffi.gc(
ctx, self._backend._lib.HMAC_CTX_cleanup
)
evp_md = self._backend._lib.EVP_get_digestbyname(
algorithm.name.encode('ascii'))
if evp_md == self._backend._ffi.NULL:
raise UnsupportedAlgorithm(
"{0} is not a supported hash on this backend".format(
algorithm.name),
_Reasons.UNSUPPORTED_HASH
)
res = self._backend._lib.Cryptography_HMAC_Init_ex(
ctx, key, len(key), evp_md, self._backend._ffi.NULL
)
assert res != 0
self._ctx = ctx
self._key = key
def copy(self):
copied_ctx = self._backend._ffi.new("HMAC_CTX *")
self._backend._lib.HMAC_CTX_init(copied_ctx)
copied_ctx = self._backend._ffi.gc(
copied_ctx, self._backend._lib.HMAC_CTX_cleanup
)
res = self._backend._lib.Cryptography_HMAC_CTX_copy(
copied_ctx, self._ctx
)
assert res != 0
return _HMACContext(
self._backend, self._key, self.algorithm, ctx=copied_ctx
)
def update(self, data):
res = self._backend._lib.Cryptography_HMAC_Update(
self._ctx, data, len(data)
)
assert res != 0
def finalize(self):
buf = self._backend._ffi.new("unsigned char[]",
self._backend._lib.EVP_MAX_MD_SIZE)
outlen = self._backend._ffi.new("unsigned int *")
res = self._backend._lib.Cryptography_HMAC_Final(
self._ctx, buf, outlen
)
assert res != 0
assert outlen[0] == self.algorithm.digest_size
self._backend._lib.HMAC_CTX_cleanup(self._ctx)
return self._backend._ffi.buffer(buf)[:outlen[0]]
def _get_rsa_pss_salt_length(pss, key_size, digest_size):
if pss._mgf._salt_length is not None:
salt = pss._mgf._salt_length
else:
salt = pss._salt_length
if salt is MGF1.MAX_LENGTH or salt is PSS.MAX_LENGTH:
# bit length - 1 per RFC 3447
emlen = int(math.ceil((key_size - 1) / 8.0))
salt_length = emlen - digest_size - 2
assert salt_length >= 0
return salt_length
else:
return salt
@utils.register_interface(interfaces.AsymmetricSignatureContext)
class _RSASignatureContext(object):
def __init__(self, backend, private_key, padding, algorithm):
self._backend = backend
self._private_key = private_key
if not isinstance(padding, interfaces.AsymmetricPadding):
raise TypeError(
"Expected provider of interfaces.AsymmetricPadding")
if isinstance(padding, PKCS1v15):
if self._backend._lib.Cryptography_HAS_PKEY_CTX:
self._finalize_method = self._finalize_pkey_ctx
self._padding_enum = self._backend._lib.RSA_PKCS1_PADDING
else:
self._finalize_method = self._finalize_pkcs1
elif isinstance(padding, PSS):
if not isinstance(padding._mgf, MGF1):
raise UnsupportedAlgorithm(
"Only MGF1 is supported by this backend",
_Reasons.UNSUPPORTED_MGF
)
# Size of key in bytes - 2 is the maximum
# PSS signature length (salt length is checked later)
key_size_bytes = int(math.ceil(private_key.key_size / 8.0))
if key_size_bytes - algorithm.digest_size - 2 < 0:
raise ValueError("Digest too large for key size. Use a larger "
"key.")
if not self._backend.mgf1_hash_supported(padding._mgf._algorithm):
raise UnsupportedAlgorithm(
"When OpenSSL is older than 1.0.1 then only SHA1 is "
"supported with MGF1.",
_Reasons.UNSUPPORTED_HASH
)
if self._backend._lib.Cryptography_HAS_PKEY_CTX:
self._finalize_method = self._finalize_pkey_ctx
self._padding_enum = self._backend._lib.RSA_PKCS1_PSS_PADDING
else:
self._finalize_method = self._finalize_pss
else:
raise UnsupportedAlgorithm(
"{0} is not supported by this backend".format(padding.name),
_Reasons.UNSUPPORTED_PADDING
)
self._padding = padding
self._algorithm = algorithm
self._hash_ctx = _HashContext(backend, self._algorithm)
def update(self, data):
if self._hash_ctx is None:
raise AlreadyFinalized("Context has already been finalized")
self._hash_ctx.update(data)
def finalize(self):
if self._hash_ctx is None:
raise AlreadyFinalized("Context has already been finalized")
evp_pkey = self._backend._rsa_private_key_to_evp_pkey(
self._private_key)
evp_md = self._backend._lib.EVP_get_digestbyname(
self._algorithm.name.encode("ascii"))
assert evp_md != self._backend._ffi.NULL
pkey_size = self._backend._lib.EVP_PKEY_size(evp_pkey)
assert pkey_size > 0
return self._finalize_method(evp_pkey, pkey_size, evp_md)
def _finalize_pkey_ctx(self, evp_pkey, pkey_size, evp_md):
pkey_ctx = self._backend._lib.EVP_PKEY_CTX_new(
evp_pkey, self._backend._ffi.NULL
)
assert pkey_ctx != self._backend._ffi.NULL
pkey_ctx = self._backend._ffi.gc(pkey_ctx,
self._backend._lib.EVP_PKEY_CTX_free)
res = self._backend._lib.EVP_PKEY_sign_init(pkey_ctx)
assert res == 1
res = self._backend._lib.EVP_PKEY_CTX_set_signature_md(
pkey_ctx, evp_md)
assert res > 0
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_padding(
pkey_ctx, self._padding_enum)
assert res > 0
if isinstance(self._padding, PSS):
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_pss_saltlen(
pkey_ctx,
_get_rsa_pss_salt_length(
self._padding,
self._private_key.key_size,
self._hash_ctx.algorithm.digest_size
)
)
assert res > 0
if self._backend._lib.Cryptography_HAS_MGF1_MD:
# MGF1 MD is configurable in OpenSSL 1.0.1+
mgf1_md = self._backend._lib.EVP_get_digestbyname(
self._padding._mgf._algorithm.name.encode("ascii"))
assert mgf1_md != self._backend._ffi.NULL
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_mgf1_md(
pkey_ctx, mgf1_md
)
assert res > 0
data_to_sign = self._hash_ctx.finalize()
self._hash_ctx = None
buflen = self._backend._ffi.new("size_t *")
res = self._backend._lib.EVP_PKEY_sign(
pkey_ctx,
self._backend._ffi.NULL,
buflen,
data_to_sign,
len(data_to_sign)
)
assert res == 1
buf = self._backend._ffi.new("unsigned char[]", buflen[0])
res = self._backend._lib.EVP_PKEY_sign(
pkey_ctx, buf, buflen, data_to_sign, len(data_to_sign))
if res != 1:
errors = self._backend._consume_errors()
assert errors[0].lib == self._backend._lib.ERR_LIB_RSA
reason = None
if (errors[0].reason ==
self._backend._lib.RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE):
reason = ("Salt length too long for key size. Try using "
"MAX_LENGTH instead.")
elif (errors[0].reason ==
self._backend._lib.RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY):
reason = "Digest too large for key size. Use a larger key."
assert reason is not None
raise ValueError(reason)
return self._backend._ffi.buffer(buf)[:]
def _finalize_pkcs1(self, evp_pkey, pkey_size, evp_md):
sig_buf = self._backend._ffi.new("char[]", pkey_size)
sig_len = self._backend._ffi.new("unsigned int *")
res = self._backend._lib.EVP_SignFinal(
self._hash_ctx._ctx,
sig_buf,
sig_len,
evp_pkey
)
self._hash_ctx.finalize()
self._hash_ctx = None
if res == 0:
errors = self._backend._consume_errors()
assert errors[0].lib == self._backend._lib.ERR_LIB_RSA
assert (errors[0].reason ==
self._backend._lib.RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY)
raise ValueError("Digest too large for key size. Use a larger "
"key.")
return self._backend._ffi.buffer(sig_buf)[:sig_len[0]]
def _finalize_pss(self, evp_pkey, pkey_size, evp_md):
data_to_sign = self._hash_ctx.finalize()
self._hash_ctx = None
padded = self._backend._ffi.new("unsigned char[]", pkey_size)
rsa_cdata = self._backend._lib.EVP_PKEY_get1_RSA(evp_pkey)
assert rsa_cdata != self._backend._ffi.NULL
rsa_cdata = self._backend._ffi.gc(rsa_cdata,
self._backend._lib.RSA_free)
res = self._backend._lib.RSA_padding_add_PKCS1_PSS(
rsa_cdata,
padded,
data_to_sign,
evp_md,
_get_rsa_pss_salt_length(
self._padding,
self._private_key.key_size,
len(data_to_sign)
)
)
if res != 1:
errors = self._backend._consume_errors()
assert errors[0].lib == self._backend._lib.ERR_LIB_RSA
assert (errors[0].reason ==
self._backend._lib.RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE)
raise ValueError("Salt length too long for key size. Try using "
"MAX_LENGTH instead.")
sig_buf = self._backend._ffi.new("char[]", pkey_size)
sig_len = self._backend._lib.RSA_private_encrypt(
pkey_size,
padded,
sig_buf,
rsa_cdata,
self._backend._lib.RSA_NO_PADDING
)
assert sig_len != -1
return self._backend._ffi.buffer(sig_buf)[:sig_len]
@utils.register_interface(interfaces.AsymmetricVerificationContext)
class _RSAVerificationContext(object):
def __init__(self, backend, public_key, signature, padding, algorithm):
self._backend = backend
self._public_key = public_key
self._signature = signature
if not isinstance(padding, interfaces.AsymmetricPadding):
raise TypeError(
"Expected provider of interfaces.AsymmetricPadding")
if isinstance(padding, PKCS1v15):
if self._backend._lib.Cryptography_HAS_PKEY_CTX:
self._verify_method = self._verify_pkey_ctx
self._padding_enum = self._backend._lib.RSA_PKCS1_PADDING
else:
self._verify_method = self._verify_pkcs1
elif isinstance(padding, PSS):
if not isinstance(padding._mgf, MGF1):
raise UnsupportedAlgorithm(
"Only MGF1 is supported by this backend",
_Reasons.UNSUPPORTED_MGF
)
# Size of key in bytes - 2 is the maximum
# PSS signature length (salt length is checked later)
key_size_bytes = int(math.ceil(public_key.key_size / 8.0))
if key_size_bytes - algorithm.digest_size - 2 < 0:
raise ValueError(
"Digest too large for key size. Check that you have the "
"correct key and digest algorithm."
)
if not self._backend.mgf1_hash_supported(padding._mgf._algorithm):
raise UnsupportedAlgorithm(
"When OpenSSL is older than 1.0.1 then only SHA1 is "
"supported with MGF1.",
_Reasons.UNSUPPORTED_HASH
)
if self._backend._lib.Cryptography_HAS_PKEY_CTX:
self._verify_method = self._verify_pkey_ctx
self._padding_enum = self._backend._lib.RSA_PKCS1_PSS_PADDING
else:
self._verify_method = self._verify_pss
else:
raise UnsupportedAlgorithm(
"{0} is not supported by this backend".format(padding.name),
_Reasons.UNSUPPORTED_PADDING
)
self._padding = padding
self._algorithm = algorithm
self._hash_ctx = _HashContext(backend, self._algorithm)
def update(self, data):
if self._hash_ctx is None:
raise AlreadyFinalized("Context has already been finalized")
self._hash_ctx.update(data)
def verify(self):
if self._hash_ctx is None:
raise AlreadyFinalized("Context has already been finalized")
evp_pkey = self._backend._rsa_public_key_to_evp_pkey(
self._public_key)
evp_md = self._backend._lib.EVP_get_digestbyname(
self._algorithm.name.encode("ascii"))
assert evp_md != self._backend._ffi.NULL
self._verify_method(evp_pkey, evp_md)
def _verify_pkey_ctx(self, evp_pkey, evp_md):
pkey_ctx = self._backend._lib.EVP_PKEY_CTX_new(
evp_pkey, self._backend._ffi.NULL
)
assert pkey_ctx != self._backend._ffi.NULL
pkey_ctx = self._backend._ffi.gc(pkey_ctx,
self._backend._lib.EVP_PKEY_CTX_free)
res = self._backend._lib.EVP_PKEY_verify_init(pkey_ctx)
assert res == 1
res = self._backend._lib.EVP_PKEY_CTX_set_signature_md(
pkey_ctx, evp_md)
assert res > 0
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_padding(
pkey_ctx, self._padding_enum)
assert res > 0
if isinstance(self._padding, PSS):
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_pss_saltlen(
pkey_ctx,
_get_rsa_pss_salt_length(
self._padding,
self._public_key.key_size,
self._hash_ctx.algorithm.digest_size
)
)
assert res > 0
if self._backend._lib.Cryptography_HAS_MGF1_MD:
# MGF1 MD is configurable in OpenSSL 1.0.1+
mgf1_md = self._backend._lib.EVP_get_digestbyname(
self._padding._mgf._algorithm.name.encode("ascii"))
assert mgf1_md != self._backend._ffi.NULL
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_mgf1_md(
pkey_ctx, mgf1_md
)
assert res > 0
data_to_verify = self._hash_ctx.finalize()
self._hash_ctx = None
res = self._backend._lib.EVP_PKEY_verify(
pkey_ctx,
self._signature,
len(self._signature),
data_to_verify,
len(data_to_verify)
)
# The previous call can return negative numbers in the event of an
# error. This is not a signature failure but we need to fail if it
# occurs.
assert res >= 0
if res == 0:
errors = self._backend._consume_errors()
assert errors
raise InvalidSignature
def _verify_pkcs1(self, evp_pkey, evp_md):
res = self._backend._lib.EVP_VerifyFinal(
self._hash_ctx._ctx,
self._signature,
len(self._signature),
evp_pkey
)
self._hash_ctx.finalize()
self._hash_ctx = None
# The previous call can return negative numbers in the event of an
# error. This is not a signature failure but we need to fail if it
# occurs.
assert res >= 0
if res == 0:
errors = self._backend._consume_errors()
assert errors
raise InvalidSignature
def _verify_pss(self, evp_pkey, evp_md):
pkey_size = self._backend._lib.EVP_PKEY_size(evp_pkey)
assert pkey_size > 0
rsa_cdata = self._backend._lib.EVP_PKEY_get1_RSA(evp_pkey)
assert rsa_cdata != self._backend._ffi.NULL
rsa_cdata = self._backend._ffi.gc(rsa_cdata,
self._backend._lib.RSA_free)
buf = self._backend._ffi.new("unsigned char[]", pkey_size)
res = self._backend._lib.RSA_public_decrypt(
len(self._signature),
self._signature,
buf,
rsa_cdata,
self._backend._lib.RSA_NO_PADDING
)
if res != pkey_size:
errors = self._backend._consume_errors()
assert errors
raise InvalidSignature
data_to_verify = self._hash_ctx.finalize()
self._hash_ctx = None
res = self._backend._lib.RSA_verify_PKCS1_PSS(
rsa_cdata,
data_to_verify,
evp_md,
buf,
_get_rsa_pss_salt_length(
self._padding,
self._public_key.key_size,
len(data_to_verify)
)
)
if res != 1:
errors = self._backend._consume_errors()
assert errors
raise InvalidSignature
@utils.register_interface(interfaces.CMACContext)
class _CMACContext(object):
def __init__(self, backend, algorithm, ctx=None):
if not backend.cmac_algorithm_supported(algorithm):
raise UnsupportedAlgorithm("This backend does not support CMAC",
_Reasons.UNSUPPORTED_CIPHER)
self._backend = backend
self._key = algorithm.key
self._algorithm = algorithm
self._output_length = algorithm.block_size // 8
if ctx is None:
registry = self._backend._cipher_registry
adapter = registry[type(algorithm), CBC]
evp_cipher = adapter(self._backend, algorithm, CBC)
ctx = self._backend._lib.CMAC_CTX_new()
assert ctx != self._backend._ffi.NULL
ctx = self._backend._ffi.gc(ctx, self._backend._lib.CMAC_CTX_free)
self._backend._lib.CMAC_Init(
ctx, self._key, len(self._key),
evp_cipher, self._backend._ffi.NULL
)
self._ctx = ctx
def update(self, data):
res = self._backend._lib.CMAC_Update(self._ctx, data, len(data))
assert res == 1
def finalize(self):
buf = self._backend._ffi.new("unsigned char[]", self._output_length)
length = self._backend._ffi.new("size_t *", self._output_length)
res = self._backend._lib.CMAC_Final(
self._ctx, buf, length
)
assert res == 1
self._ctx = None
return self._backend._ffi.buffer(buf)[:]
def copy(self):
copied_ctx = self._backend._lib.CMAC_CTX_new()
copied_ctx = self._backend._ffi.gc(
copied_ctx, self._backend._lib.CMAC_CTX_free
)
res = self._backend._lib.CMAC_CTX_copy(
copied_ctx, self._ctx
)
assert res == 1
return _CMACContext(
self._backend, self._algorithm, ctx=copied_ctx
)
backend = Backend()
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