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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 warnings
import six
from cryptography import utils
from cryptography.exceptions import (
InternalError, UnsupportedAlgorithm, _Reasons
)
from cryptography.hazmat.backends.interfaces import (
CMACBackend, CipherBackend, DSABackend, EllipticCurveBackend, HMACBackend,
HashBackend, PBKDF2HMACBackend, PEMSerializationBackend,
PKCS8SerializationBackend, RSABackend,
TraditionalOpenSSLSerializationBackend
)
from cryptography.hazmat.backends.openssl.ciphers import (
_AESCTRCipherContext, _CipherContext
)
from cryptography.hazmat.backends.openssl.cmac import _CMACContext
from cryptography.hazmat.backends.openssl.dsa import (
_DSAParameters, _DSAPrivateKey, _DSAPublicKey,
_DSASignatureContext, _DSAVerificationContext
)
from cryptography.hazmat.backends.openssl.ec import (
_EllipticCurvePrivateKey, _EllipticCurvePublicKey
)
from cryptography.hazmat.backends.openssl.hashes import _HashContext
from cryptography.hazmat.backends.openssl.hmac import _HMACContext
from cryptography.hazmat.backends.openssl.rsa import (
_RSAPrivateKey, _RSAPublicKey, _RSASignatureContext,
_RSAVerificationContext
)
from cryptography.hazmat.bindings.openssl.binding import Binding
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import dsa, ec, rsa
from cryptography.hazmat.primitives.asymmetric.padding import (
MGF1, OAEP, 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, CFB8, CTR, ECB, GCM, OFB
)
_MemoryBIO = collections.namedtuple("_MemoryBIO", ["bio", "char_ptr"])
_OpenSSLError = collections.namedtuple("_OpenSSLError",
["code", "lib", "func", "reason"])
@utils.register_interface(CipherBackend)
@utils.register_interface(CMACBackend)
@utils.register_interface(DSABackend)
@utils.register_interface(EllipticCurveBackend)
@utils.register_interface(HashBackend)
@utils.register_interface(HMACBackend)
@utils.register_interface(PBKDF2HMACBackend)
@utils.register_interface(PKCS8SerializationBackend)
@utils.register_interface(RSABackend)
@utils.register_interface(TraditionalOpenSSLSerializationBackend)
@utils.register_interface(PEMSerializationBackend)
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 the loaded OpenSSL library. This is not
necessarily the same version as it was compiled against.
Example: OpenSSL 1.0.1e 11 Feb 2013
"""
return self._ffi.string(
self._lib.SSLeay_version(self._lib.SSLEAY_VERSION)
).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):
if self._evp_cipher_supported(cipher, mode):
return True
elif isinstance(mode, CTR) and isinstance(cipher, AES):
return True
else:
return False
def _evp_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 mode_cls in [CBC, CTR, ECB, OFB, CFB, CFB8]:
self.register_cipher_adapter(
AES,
mode_cls,
GetCipherByName("{cipher.name}-{cipher.key_size}-{mode.name}")
)
for mode_cls in [CBC, CTR, ECB, OFB, CFB]:
self.register_cipher_adapter(
Camellia,
mode_cls,
GetCipherByName("{cipher.name}-{cipher.key_size}-{mode.name}")
)
for mode_cls in [CBC, CFB, CFB8, OFB]:
self.register_cipher_adapter(
TripleDES,
mode_cls,
GetCipherByName("des-ede3-{mode.name}")
)
self.register_cipher_adapter(
TripleDES,
ECB,
GetCipherByName("des-ede3")
)
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):
if (isinstance(mode, CTR) and isinstance(cipher, AES)
and not self._evp_cipher_supported(cipher, mode)):
# This is needed to provide support for AES CTR mode in OpenSSL
# 0.9.8. It can be removed when we drop 0.9.8 support (RHEL 5
# extended life ends 2020).
return _AESCTRCipherContext(self, cipher, mode)
else:
return _CipherContext(self, cipher, mode, _CipherContext._ENCRYPT)
def create_symmetric_decryption_ctx(self, cipher, mode):
if (isinstance(mode, CTR) and isinstance(cipher, AES)
and not self._evp_cipher_supported(cipher, mode)):
# This is needed to provide support for AES CTR mode in OpenSSL
# 0.9.8. It can be removed when we drop 0.9.8 support (RHEL 5
# extended life ends 2020).
return _AESCTRCipherContext(self, cipher, mode)
else:
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):
rsa._verify_rsa_parameters(public_exponent, key_size)
rsa_cdata = self._lib.RSA_new()
assert rsa_cdata != self._ffi.NULL
rsa_cdata = self._ffi.gc(rsa_cdata, 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(
rsa_cdata, key_size, bn, self._ffi.NULL
)
assert res == 1
return _RSAPrivateKey(self, rsa_cdata)
def generate_rsa_parameters_supported(self, public_exponent, key_size):
return (public_exponent >= 3 and public_exponent & 1 != 0 and
key_size >= 512)
def load_rsa_private_numbers(self, numbers):
rsa._check_private_key_components(
numbers.p,
numbers.q,
numbers.d,
numbers.dmp1,
numbers.dmq1,
numbers.iqmp,
numbers.public_numbers.e,
numbers.public_numbers.n
)
rsa_cdata = self._lib.RSA_new()
assert rsa_cdata != self._ffi.NULL
rsa_cdata = self._ffi.gc(rsa_cdata, self._lib.RSA_free)
rsa_cdata.p = self._int_to_bn(numbers.p)
rsa_cdata.q = self._int_to_bn(numbers.q)
rsa_cdata.d = self._int_to_bn(numbers.d)
rsa_cdata.dmp1 = self._int_to_bn(numbers.dmp1)
rsa_cdata.dmq1 = self._int_to_bn(numbers.dmq1)
rsa_cdata.iqmp = self._int_to_bn(numbers.iqmp)
rsa_cdata.e = self._int_to_bn(numbers.public_numbers.e)
rsa_cdata.n = self._int_to_bn(numbers.public_numbers.n)
res = self._lib.RSA_blinding_on(rsa_cdata, self._ffi.NULL)
assert res == 1
return _RSAPrivateKey(self, rsa_cdata)
def load_rsa_public_numbers(self, numbers):
rsa._check_public_key_components(numbers.e, numbers.n)
rsa_cdata = self._lib.RSA_new()
assert rsa_cdata != self._ffi.NULL
rsa_cdata = self._ffi.gc(rsa_cdata, self._lib.RSA_free)
rsa_cdata.e = self._int_to_bn(numbers.e)
rsa_cdata.n = self._int_to_bn(numbers.n)
res = self._lib.RSA_blinding_on(rsa_cdata, self._ffi.NULL)
assert res == 1
return _RSAPublicKey(self, rsa_cdata)
def _bytes_to_bio(self, data):
"""
Return a _MemoryBIO namedtuple of (BIO, char*).
The char* is the storage for the BIO and it must stay alive until the
BIO is finished with.
"""
data_char_p = self._ffi.new("char[]", data)
bio = self._lib.BIO_new_mem_buf(
data_char_p, len(data)
)
assert bio != self._ffi.NULL
return _MemoryBIO(self._ffi.gc(bio, self._lib.BIO_free), data_char_p)
def _evp_pkey_to_private_key(self, evp_pkey):
"""
Return the appropriate type of PrivateKey given an evp_pkey cdata
pointer.
"""
type = evp_pkey.type
if type == self._lib.EVP_PKEY_RSA:
rsa_cdata = self._lib.EVP_PKEY_get1_RSA(evp_pkey)
assert rsa_cdata != self._ffi.NULL
rsa_cdata = self._ffi.gc(rsa_cdata, self._lib.RSA_free)
return _RSAPrivateKey(self, rsa_cdata)
elif type == self._lib.EVP_PKEY_DSA:
dsa_cdata = self._lib.EVP_PKEY_get1_DSA(evp_pkey)
assert dsa_cdata != self._ffi.NULL
dsa_cdata = self._ffi.gc(dsa_cdata, self._lib.DSA_free)
return _DSAPrivateKey(self, dsa_cdata)
else:
raise UnsupportedAlgorithm("Unsupported key type.")
def _pem_password_cb(self, password):
"""
Generate a pem_password_cb function pointer that copied the password to
OpenSSL as required and returns the number of bytes copied.
typedef int pem_password_cb(char *buf, int size,
int rwflag, void *userdata);
Useful for decrypting PKCS8 files and so on.
Returns a tuple of (cdata function pointer, callback function).
"""
def pem_password_cb(buf, size, writing, userdata):
pem_password_cb.called += 1
if not password:
pem_password_cb.exception = TypeError(
"Password was not given but private key is encrypted."
)
return 0
elif len(password) < size:
pw_buf = self._ffi.buffer(buf, size)
pw_buf[:len(password)] = password
return len(password)
else:
pem_password_cb.exception = ValueError(
"Passwords longer than {0} bytes are not supported "
"by this backend.".format(size - 1)
)
return 0
pem_password_cb.called = 0
pem_password_cb.exception = None
return (
self._ffi.callback("int (char *, int, int, void *)",
pem_password_cb),
pem_password_cb
)
def _rsa_cdata_from_private_key(self, private_key):
ctx = self._lib.RSA_new()
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.RSA_free)
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):
ctx = self._lib.RSA_new()
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.RSA_free)
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):
warnings.warn(
"create_rsa_signature_ctx is deprecated and will be removed in a "
"future version.",
utils.DeprecatedIn05,
stacklevel=2
)
rsa_cdata = self._rsa_cdata_from_private_key(private_key)
key = _RSAPrivateKey(self, rsa_cdata)
return _RSASignatureContext(self, key, padding, algorithm)
def create_rsa_verification_ctx(self, public_key, signature, padding,
algorithm):
warnings.warn(
"create_rsa_verification_ctx is deprecated and will be removed in "
"a future version.",
utils.DeprecatedIn05,
stacklevel=2
)
rsa_cdata = self._rsa_cdata_from_public_key(public_key)
key = _RSAPublicKey(self, rsa_cdata)
return _RSAVerificationContext(self, key, signature, padding,
algorithm)
def mgf1_hash_supported(self, algorithm):
warnings.warn(
"mgf1_hash_supported is deprecated and will be removed in "
"a future version.",
utils.DeprecatedIn05,
stacklevel=2
)
return self._mgf1_hash_supported(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 rsa_padding_supported(self, padding):
if isinstance(padding, PKCS1v15):
return True
elif isinstance(padding, PSS) and isinstance(padding._mgf, MGF1):
return self._mgf1_hash_supported(padding._mgf._algorithm)
elif isinstance(padding, OAEP) and isinstance(padding._mgf, MGF1):
return isinstance(padding._mgf._algorithm, hashes.SHA1)
else:
return False
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 _DSAParameters(self, ctx)
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)
if isinstance(parameters, dsa.DSAParameters):
ctx.p = self._int_to_bn(parameters.p)
ctx.q = self._int_to_bn(parameters.q)
ctx.g = self._int_to_bn(parameters.g)
else:
ctx.p = self._lib.BN_dup(parameters._dsa_cdata.p)
ctx.q = self._lib.BN_dup(parameters._dsa_cdata.q)
ctx.g = self._lib.BN_dup(parameters._dsa_cdata.g)
self._lib.DSA_generate_key(ctx)
return _DSAPrivateKey(self, ctx)
def generate_dsa_private_key_and_parameters(self, key_size):
parameters = self.generate_dsa_parameters(key_size)
return self.generate_dsa_private_key(parameters)
def create_dsa_signature_ctx(self, private_key, algorithm):
warnings.warn(
"create_dsa_signature_ctx is deprecated and will be removed in "
"a future version.",
utils.DeprecatedIn05,
stacklevel=2
)
dsa_cdata = self._dsa_cdata_from_private_key(private_key)
key = _DSAPrivateKey(self, dsa_cdata)
return _DSASignatureContext(self, key, algorithm)
def create_dsa_verification_ctx(self, public_key, signature,
algorithm):
warnings.warn(
"create_dsa_verification_ctx is deprecated and will be removed in "
"a future version.",
utils.DeprecatedIn05,
stacklevel=2
)
dsa_cdata = self._dsa_cdata_from_public_key(public_key)
key = _DSAPublicKey(self, dsa_cdata)
return _DSAVerificationContext(self, key, signature, algorithm)
def load_dsa_private_numbers(self, numbers):
dsa._check_dsa_private_numbers(numbers)
parameter_numbers = numbers.public_numbers.parameter_numbers
dsa_cdata = self._lib.DSA_new()
assert dsa_cdata != self._ffi.NULL
dsa_cdata = self._ffi.gc(dsa_cdata, self._lib.DSA_free)
dsa_cdata.p = self._int_to_bn(parameter_numbers.p)
dsa_cdata.q = self._int_to_bn(parameter_numbers.q)
dsa_cdata.g = self._int_to_bn(parameter_numbers.g)
dsa_cdata.pub_key = self._int_to_bn(numbers.public_numbers.y)
dsa_cdata.priv_key = self._int_to_bn(numbers.x)
return _DSAPrivateKey(self, dsa_cdata)
def load_dsa_public_numbers(self, numbers):
dsa._check_dsa_parameters(numbers.parameter_numbers)
dsa_cdata = self._lib.DSA_new()
assert dsa_cdata != self._ffi.NULL
dsa_cdata = self._ffi.gc(dsa_cdata, self._lib.DSA_free)
dsa_cdata.p = self._int_to_bn(numbers.parameter_numbers.p)
dsa_cdata.q = self._int_to_bn(numbers.parameter_numbers.q)
dsa_cdata.g = self._int_to_bn(numbers.parameter_numbers.g)
dsa_cdata.pub_key = self._int_to_bn(numbers.y)
return _DSAPublicKey(self, dsa_cdata)
def load_dsa_parameter_numbers(self, numbers):
dsa._check_dsa_parameters(numbers)
dsa_cdata = self._lib.DSA_new()
assert dsa_cdata != self._ffi.NULL
dsa_cdata = self._ffi.gc(dsa_cdata, self._lib.DSA_free)
dsa_cdata.p = self._int_to_bn(numbers.p)
dsa_cdata.q = self._int_to_bn(numbers.q)
dsa_cdata.g = self._int_to_bn(numbers.g)
return _DSAParameters(self, dsa_cdata)
def _dsa_cdata_from_public_key(self, public_key):
ctx = self._lib.DSA_new()
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.DSA_free)
parameters = public_key.parameters()
ctx.p = self._int_to_bn(parameters.p)
ctx.q = self._int_to_bn(parameters.q)
ctx.g = self._int_to_bn(parameters.g)
ctx.pub_key = self._int_to_bn(public_key.y)
return ctx
def _dsa_cdata_from_private_key(self, private_key):
ctx = self._lib.DSA_new()
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.DSA_free)
parameters = private_key.parameters()
ctx.p = self._int_to_bn(parameters.p)
ctx.q = self._int_to_bn(parameters.q)
ctx.g = self._int_to_bn(parameters.g)
ctx.priv_key = self._int_to_bn(private_key.x)
ctx.pub_key = self._int_to_bn(private_key.y)
return ctx
def dsa_hash_supported(self, algorithm):
if self._lib.OPENSSL_VERSION_NUMBER < 0x1000000f:
return isinstance(algorithm, hashes.SHA1)
else:
return self.hash_supported(algorithm)
def dsa_parameters_supported(self, p, q, g):
if self._lib.OPENSSL_VERSION_NUMBER < 0x1000000f:
return (utils.bit_length(p) <= 1024 and utils.bit_length(q) <= 160)
else:
return True
def decrypt_rsa(self, private_key, ciphertext, padding):
warnings.warn(
"decrypt_rsa is deprecated and will be removed in a future "
"version.",
utils.DeprecatedIn05,
stacklevel=2
)
rsa_cdata = self._rsa_cdata_from_private_key(private_key)
key = _RSAPrivateKey(self, rsa_cdata)
return key.decrypt(ciphertext, padding)
def encrypt_rsa(self, public_key, plaintext, padding):
warnings.warn(
"encrypt_rsa is deprecated and will be removed in a future "
"version.",
utils.DeprecatedIn05,
stacklevel=2
)
rsa_cdata = self._rsa_cdata_from_public_key(public_key)
key = _RSAPublicKey(self, rsa_cdata)
return key.encrypt(plaintext, padding)
def cmac_algorithm_supported(self, algorithm):
return (
self._lib.Cryptography_HAS_CMAC == 1
and self.cipher_supported(algorithm, CBC(
b"\x00" * algorithm.block_size))
)
def create_cmac_ctx(self, algorithm):
return _CMACContext(self, algorithm)
def load_pem_private_key(self, data, password):
return self._load_key(
self._lib.PEM_read_bio_PrivateKey,
self._evp_pkey_to_private_key,
data,
password,
)
def load_traditional_openssl_pem_private_key(self, data, password):
warnings.warn(
"load_traditional_openssl_pem_private_key is deprecated and will "
"be removed in a future version, use load_pem_private_key "
"instead.",
utils.DeprecatedIn06,
stacklevel=2
)
return self.load_pem_private_key(self, data, password)
def load_pkcs8_pem_private_key(self, data, password):
warnings.warn(
"load_pkcs8_pem_private_key is deprecated and will be removed in a"
" future version, use load_pem_private_key instead.",
utils.DeprecatedIn06,
stacklevel=2
)
return self.load_pem_private_key(self, data, password)
def _load_key(self, openssl_read_func, convert_func, data, password):
mem_bio = self._bytes_to_bio(data)
password_callback, password_func = self._pem_password_cb(password)
evp_pkey = openssl_read_func(
mem_bio.bio,
self._ffi.NULL,
password_callback,
self._ffi.NULL
)
if evp_pkey == self._ffi.NULL:
if password_func.exception is not None:
errors = self._consume_errors()
assert errors
raise password_func.exception
else:
self._handle_key_loading_error()
evp_pkey = self._ffi.gc(evp_pkey, self._lib.EVP_PKEY_free)
if password is not None and password_func.called == 0:
raise TypeError(
"Password was given but private key is not encrypted.")
assert (
(password is not None and password_func.called == 1) or
password is None
)
return convert_func(evp_pkey)
def _handle_key_loading_error(self):
errors = self._consume_errors()
if not errors:
raise ValueError("Could not unserialize key data.")
elif errors[0][1:] == (
self._lib.ERR_LIB_EVP,
self._lib.EVP_F_EVP_DECRYPTFINAL_EX,
self._lib.EVP_R_BAD_DECRYPT
):
raise ValueError("Bad decrypt. Incorrect password?")
elif errors[0][1:] in (
(
self._lib.ERR_LIB_PEM,
self._lib.PEM_F_PEM_GET_EVP_CIPHER_INFO,
self._lib.PEM_R_UNSUPPORTED_ENCRYPTION
),
(
self._lib.ERR_LIB_EVP,
self._lib.EVP_F_EVP_PBE_CIPHERINIT,
self._lib.EVP_R_UNKNOWN_PBE_ALGORITHM
)
):
raise UnsupportedAlgorithm(
"PEM data is encrypted with an unsupported cipher",
_Reasons.UNSUPPORTED_CIPHER
)
elif any(
error[1:] == (
self._lib.ERR_LIB_EVP,
self._lib.EVP_F_EVP_PKCS82PKEY,
self._lib.EVP_R_UNSUPPORTED_PRIVATE_KEY_ALGORITHM
)
for error in errors
):
raise UnsupportedAlgorithm(
"Unsupported public key algorithm.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM
)
else:
assert errors[0][1] in (
self._lib.ERR_LIB_EVP,
self._lib.ERR_LIB_PEM,
self._lib.ERR_LIB_ASN1,
)
raise ValueError("Could not unserialize key data.")
def elliptic_curve_supported(self, curve):
if self._lib.Cryptography_HAS_EC != 1:
return False
try:
curve_nid = self._elliptic_curve_to_nid(curve)
except UnsupportedAlgorithm:
curve_nid = self._lib.NID_undef
ctx = self._lib.EC_GROUP_new_by_curve_name(curve_nid)
if ctx == self._ffi.NULL:
errors = self._consume_errors()
assert (
curve_nid == self._lib.NID_undef or
errors[0][1:] == (
self._lib.ERR_LIB_EC,
self._lib.EC_F_EC_GROUP_NEW_BY_CURVE_NAME,
self._lib.EC_R_UNKNOWN_GROUP
)
)
return False
else:
assert curve_nid != self._lib.NID_undef
self._lib.EC_GROUP_free(ctx)
return True
def elliptic_curve_signature_algorithm_supported(
self, signature_algorithm, curve
):
if self._lib.Cryptography_HAS_EC != 1:
return False
# We only support ECDSA right now.
if not isinstance(signature_algorithm, ec.ECDSA):
return False
# Before 0.9.8m OpenSSL can't cope with digests longer than the curve.
if (
self._lib.OPENSSL_VERSION_NUMBER < 0x009080df and
curve.key_size < signature_algorithm.algorithm.digest_size * 8
):
return False
return self.elliptic_curve_supported(curve)
def generate_elliptic_curve_private_key(self, curve):
"""
Generate a new private key on the named curve.
"""
if self.elliptic_curve_supported(curve):
curve_nid = self._elliptic_curve_to_nid(curve)
ctx = self._lib.EC_KEY_new_by_curve_name(curve_nid)
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.EC_KEY_free)
res = self._lib.EC_KEY_generate_key(ctx)
assert res == 1
res = self._lib.EC_KEY_check_key(ctx)
assert res == 1
return _EllipticCurvePrivateKey(self, ctx, curve)
else:
raise UnsupportedAlgorithm(
"Backend object does not support {0}.".format(curve.name),
_Reasons.UNSUPPORTED_ELLIPTIC_CURVE
)
def elliptic_curve_private_key_from_numbers(self, numbers):
public = numbers.public_numbers
curve_nid = self._elliptic_curve_to_nid(public.curve)
ctx = self._lib.EC_KEY_new_by_curve_name(curve_nid)
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.EC_KEY_free)
ctx = self._ec_key_set_public_key_affine_coordinates(
ctx, public.x, public.y)
res = self._lib.EC_KEY_set_private_key(
ctx, self._int_to_bn(numbers.private_value))
assert res == 1
return _EllipticCurvePrivateKey(self, ctx,
numbers.public_numbers.curve)
def elliptic_curve_public_key_from_numbers(self, numbers):
curve_nid = self._elliptic_curve_to_nid(numbers.curve)
ctx = self._lib.EC_KEY_new_by_curve_name(curve_nid)
assert ctx != self._ffi.NULL
ctx = self._ffi.gc(ctx, self._lib.EC_KEY_free)
ctx = self._ec_key_set_public_key_affine_coordinates(
ctx, numbers.x, numbers.y)
return _EllipticCurvePublicKey(self, ctx, numbers.curve)
def _elliptic_curve_to_nid(self, curve):
"""
Get the NID for a curve name.
"""
curve_aliases = {
"secp192r1": "prime192v1",
"secp256r1": "prime256v1"
}
curve_name = curve_aliases.get(curve.name, curve.name)
curve_nid = self._lib.OBJ_sn2nid(curve_name.encode())
if curve_nid == self._lib.NID_undef:
raise UnsupportedAlgorithm(
"{0} is not a supported elliptic curve".format(curve.name),
_Reasons.UNSUPPORTED_ELLIPTIC_CURVE
)
return curve_nid
def _ec_key_set_public_key_affine_coordinates(self, ctx, x, y):
"""
This is a port of EC_KEY_set_public_key_affine_coordinates that was
added in 1.0.1.
Sets the public key point in the EC_KEY context to the affine x and y
values.
"""
assert ctx != self._ffi.NULL
bn_x = self._int_to_bn(x)
bn_y = self._int_to_bn(y)
nid_two_field = self._lib.OBJ_sn2nid(b"characteristic-two-field")
assert nid_two_field != self._lib.NID_undef
bn_ctx = self._lib.BN_CTX_new()
assert bn_ctx != self._ffi.NULL
bn_ctx = self._ffi.gc(bn_ctx, self._lib.BN_CTX_free)
group = self._lib.EC_KEY_get0_group(ctx)
assert group != self._ffi.NULL
point = self._lib.EC_POINT_new(group)
assert point != self._ffi.NULL
point = self._ffi.gc(point, self._lib.EC_POINT_free)
method = self._lib.EC_GROUP_method_of(group)
assert method != self._ffi.NULL
nid = self._lib.EC_METHOD_get_field_type(method)
assert nid != self._lib.NID_undef
check_x = self._lib.BN_CTX_get(bn_ctx)
check_y = self._lib.BN_CTX_get(bn_ctx)
if nid == nid_two_field and self._lib.Cryptography_HAS_EC2M:
set_func = self._lib.EC_POINT_set_affine_coordinates_GF2m
get_func = self._lib.EC_POINT_get_affine_coordinates_GF2m
else:
set_func = self._lib.EC_POINT_set_affine_coordinates_GFp
get_func = self._lib.EC_POINT_get_affine_coordinates_GFp
assert set_func and get_func
res = set_func(group, point, bn_x, bn_y, bn_ctx)
assert res == 1
res = get_func(group, point, check_x, check_y, bn_ctx)
assert res == 1
assert (
self._lib.BN_cmp(bn_x, check_x) == 0 and
self._lib.BN_cmp(bn_y, check_y) == 0
)
res = self._lib.EC_KEY_set_public_key(ctx, point)
assert res == 1
res = self._lib.EC_KEY_check_key(ctx)
assert res == 1
return ctx
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"))
backend = Backend()
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