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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.
from __future__ import absolute_import, division, print_function
from cryptography import utils
from cryptography.exceptions import UnsupportedAlgorithm, _Reasons
from cryptography.hazmat.backends.interfaces import (
CMACBackend, CipherBackend, DERSerializationBackend, DHBackend,
DSABackend, EllipticCurveBackend, HMACBackend, HashBackend,
PBKDF2HMACBackend, PEMSerializationBackend, RSABackend, ScryptBackend,
X509Backend
)
@utils.register_interface(CMACBackend)
@utils.register_interface(CipherBackend)
@utils.register_interface(DERSerializationBackend)
@utils.register_interface(HashBackend)
@utils.register_interface(HMACBackend)
@utils.register_interface(PBKDF2HMACBackend)
@utils.register_interface(RSABackend)
@utils.register_interface(DSABackend)
@utils.register_interface(EllipticCurveBackend)
@utils.register_interface(PEMSerializationBackend)
@utils.register_interface(X509Backend)
@utils.register_interface(DHBackend)
@utils.register_interface(ScryptBackend)
class MultiBackend(object):
name = "multibackend"
def __init__(self, backends):
if len(backends) == 0:
raise ValueError(
"Multibackend cannot be initialized with no backends. If you "
"are seeing this error when trying to use default_backend() "
"please try uninstalling and reinstalling cryptography."
)
self._backends = backends
def _filtered_backends(self, interface):
for b in self._backends:
if isinstance(b, interface):
yield b
def cipher_supported(self, cipher, mode):
return any(
b.cipher_supported(cipher, mode)
for b in self._filtered_backends(CipherBackend)
)
def create_symmetric_encryption_ctx(self, cipher, mode):
for b in self._filtered_backends(CipherBackend):
try:
return b.create_symmetric_encryption_ctx(cipher, mode)
except UnsupportedAlgorithm:
pass
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
)
def create_symmetric_decryption_ctx(self, cipher, mode):
for b in self._filtered_backends(CipherBackend):
try:
return b.create_symmetric_decryption_ctx(cipher, mode)
except UnsupportedAlgorithm:
pass
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
)
def hash_supported(self, algorithm):
return any(
b.hash_supported(algorithm)
for b in self._filtered_backends(HashBackend)
)
def create_hash_ctx(self, algorithm):
for b in self._filtered_backends(HashBackend):
try:
return b.create_hash_ctx(algorithm)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm(
"{0} is not a supported hash on this backend.".format(
algorithm.name),
_Reasons.UNSUPPORTED_HASH
)
def hmac_supported(self, algorithm):
return any(
b.hmac_supported(algorithm)
for b in self._filtered_backends(HMACBackend)
)
def create_hmac_ctx(self, key, algorithm):
for b in self._filtered_backends(HMACBackend):
try:
return b.create_hmac_ctx(key, algorithm)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm(
"{0} is not a supported hash on this backend.".format(
algorithm.name),
_Reasons.UNSUPPORTED_HASH
)
def pbkdf2_hmac_supported(self, algorithm):
return any(
b.pbkdf2_hmac_supported(algorithm)
for b in self._filtered_backends(PBKDF2HMACBackend)
)
def derive_pbkdf2_hmac(self, algorithm, length, salt, iterations,
key_material):
for b in self._filtered_backends(PBKDF2HMACBackend):
try:
return b.derive_pbkdf2_hmac(
algorithm, length, salt, iterations, key_material
)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm(
"{0} is not a supported hash on this backend.".format(
algorithm.name),
_Reasons.UNSUPPORTED_HASH
)
def generate_rsa_private_key(self, public_exponent, key_size):
for b in self._filtered_backends(RSABackend):
return b.generate_rsa_private_key(public_exponent, key_size)
raise UnsupportedAlgorithm("RSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def generate_rsa_parameters_supported(self, public_exponent, key_size):
for b in self._filtered_backends(RSABackend):
return b.generate_rsa_parameters_supported(
public_exponent, key_size
)
raise UnsupportedAlgorithm("RSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def rsa_padding_supported(self, padding):
for b in self._filtered_backends(RSABackend):
return b.rsa_padding_supported(padding)
raise UnsupportedAlgorithm("RSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def load_rsa_private_numbers(self, numbers):
for b in self._filtered_backends(RSABackend):
return b.load_rsa_private_numbers(numbers)
raise UnsupportedAlgorithm("RSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def load_rsa_public_numbers(self, numbers):
for b in self._filtered_backends(RSABackend):
return b.load_rsa_public_numbers(numbers)
raise UnsupportedAlgorithm("RSA is not supported by the backend",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def generate_dsa_parameters(self, key_size):
for b in self._filtered_backends(DSABackend):
return b.generate_dsa_parameters(key_size)
raise UnsupportedAlgorithm("DSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def generate_dsa_private_key(self, parameters):
for b in self._filtered_backends(DSABackend):
return b.generate_dsa_private_key(parameters)
raise UnsupportedAlgorithm("DSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def generate_dsa_private_key_and_parameters(self, key_size):
for b in self._filtered_backends(DSABackend):
return b.generate_dsa_private_key_and_parameters(key_size)
raise UnsupportedAlgorithm("DSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def dsa_hash_supported(self, algorithm):
for b in self._filtered_backends(DSABackend):
return b.dsa_hash_supported(algorithm)
raise UnsupportedAlgorithm("DSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def dsa_parameters_supported(self, p, q, g):
for b in self._filtered_backends(DSABackend):
return b.dsa_parameters_supported(p, q, g)
raise UnsupportedAlgorithm("DSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def load_dsa_public_numbers(self, numbers):
for b in self._filtered_backends(DSABackend):
return b.load_dsa_public_numbers(numbers)
raise UnsupportedAlgorithm("DSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def load_dsa_private_numbers(self, numbers):
for b in self._filtered_backends(DSABackend):
return b.load_dsa_private_numbers(numbers)
raise UnsupportedAlgorithm("DSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def load_dsa_parameter_numbers(self, numbers):
for b in self._filtered_backends(DSABackend):
return b.load_dsa_parameter_numbers(numbers)
raise UnsupportedAlgorithm("DSA is not supported by the backend.",
_Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
def cmac_algorithm_supported(self, algorithm):
return any(
b.cmac_algorithm_supported(algorithm)
for b in self._filtered_backends(CMACBackend)
)
def create_cmac_ctx(self, algorithm):
for b in self._filtered_backends(CMACBackend):
try:
return b.create_cmac_ctx(algorithm)
except UnsupportedAlgorithm:
pass
raise UnsupportedAlgorithm("This backend does not support CMAC.",
_Reasons.UNSUPPORTED_CIPHER)
def elliptic_curve_supported(self, curve):
return any(
b.elliptic_curve_supported(curve)
for b in self._filtered_backends(EllipticCurveBackend)
)
def elliptic_curve_signature_algorithm_supported(
self, signature_algorithm, curve
):
return any(
b.elliptic_curve_signature_algorithm_supported(
signature_algorithm, curve
)
for b in self._filtered_backends(EllipticCurveBackend)
)
def generate_elliptic_curve_private_key(self, curve):
for b in self._filtered_backends(EllipticCurveBackend):
try:
return b.generate_elliptic_curve_private_key(curve)
except UnsupportedAlgorithm:
continue
raise UnsupportedAlgorithm(
"This backend does not support this elliptic curve.",
_Reasons.UNSUPPORTED_ELLIPTIC_CURVE
)
def load_elliptic_curve_private_numbers(self, numbers):
for b in self._filtered_backends(EllipticCurveBackend):
try:
return b.load_elliptic_curve_private_numbers(numbers)
except UnsupportedAlgorithm:
continue
raise UnsupportedAlgorithm(
"This backend does not support this elliptic curve.",
_Reasons.UNSUPPORTED_ELLIPTIC_CURVE
)
def load_elliptic_curve_public_numbers(self, numbers):
for b in self._filtered_backends(EllipticCurveBackend):
try:
return b.load_elliptic_curve_public_numbers(numbers)
except UnsupportedAlgorithm:
continue
raise UnsupportedAlgorithm(
"This backend does not support this elliptic curve.",
_Reasons.UNSUPPORTED_ELLIPTIC_CURVE
)
def derive_elliptic_curve_private_key(self, private_value, curve):
for b in self._filtered_backends(EllipticCurveBackend):
try:
return b.derive_elliptic_curve_private_key(private_value,
curve)
except UnsupportedAlgorithm:
continue
raise UnsupportedAlgorithm(
"This backend does not support this elliptic curve.",
_Reasons.UNSUPPORTED_ELLIPTIC_CURVE
)
def elliptic_curve_exchange_algorithm_supported(self, algorithm, curve):
return any(
b.elliptic_curve_exchange_algorithm_supported(algorithm, curve)
for b in self._filtered_backends(EllipticCurveBackend)
)
def load_pem_private_key(self, data, password):
for b in self._filtered_backends(PEMSerializationBackend):
return b.load_pem_private_key(data, password)
raise UnsupportedAlgorithm(
"This backend does not support this key serialization.",
_Reasons.UNSUPPORTED_SERIALIZATION
)
def load_pem_public_key(self, data):
for b in self._filtered_backends(PEMSerializationBackend):
return b.load_pem_public_key(data)
raise UnsupportedAlgorithm(
"This backend does not support this key serialization.",
_Reasons.UNSUPPORTED_SERIALIZATION
)
def load_der_private_key(self, data, password):
for b in self._filtered_backends(DERSerializationBackend):
return b.load_der_private_key(data, password)
raise UnsupportedAlgorithm(
"This backend does not support this key serialization.",
_Reasons.UNSUPPORTED_SERIALIZATION
)
def load_der_public_key(self, data):
for b in self._filtered_backends(DERSerializationBackend):
return b.load_der_public_key(data)
raise UnsupportedAlgorithm(
"This backend does not support this key serialization.",
_Reasons.UNSUPPORTED_SERIALIZATION
)
def load_pem_x509_certificate(self, data):
for b in self._filtered_backends(X509Backend):
return b.load_pem_x509_certificate(data)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def load_der_x509_certificate(self, data):
for b in self._filtered_backends(X509Backend):
return b.load_der_x509_certificate(data)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def load_pem_x509_crl(self, data):
for b in self._filtered_backends(X509Backend):
return b.load_pem_x509_crl(data)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def load_der_x509_crl(self, data):
for b in self._filtered_backends(X509Backend):
return b.load_der_x509_crl(data)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def load_der_x509_csr(self, data):
for b in self._filtered_backends(X509Backend):
return b.load_der_x509_csr(data)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def load_pem_x509_csr(self, data):
for b in self._filtered_backends(X509Backend):
return b.load_pem_x509_csr(data)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def create_x509_csr(self, builder, private_key, algorithm):
for b in self._filtered_backends(X509Backend):
return b.create_x509_csr(builder, private_key, algorithm)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def create_x509_certificate(self, builder, private_key, algorithm):
for b in self._filtered_backends(X509Backend):
return b.create_x509_certificate(builder, private_key, algorithm)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def create_x509_crl(self, builder, private_key, algorithm):
for b in self._filtered_backends(X509Backend):
return b.create_x509_crl(builder, private_key, algorithm)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def create_x509_revoked_certificate(self, builder):
for b in self._filtered_backends(X509Backend):
return b.create_x509_revoked_certificate(builder)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def generate_dh_parameters(self, generator, key_size):
for b in self._filtered_backends(DHBackend):
return b.generate_dh_parameters(generator, key_size)
raise UnsupportedAlgorithm(
"This backend does not support Diffie-Hellman",
_Reasons.UNSUPPORTED_DIFFIE_HELLMAN
)
def load_dh_parameter_numbers(self, numbers):
for b in self._filtered_backends(DHBackend):
return b.load_dh_parameter_numbers(numbers)
raise UnsupportedAlgorithm(
"This backend does not support Diffie-Hellman",
_Reasons.UNSUPPORTED_DIFFIE_HELLMAN
)
def generate_dh_private_key(self, parameters):
for b in self._filtered_backends(DHBackend):
return b.generate_dh_private_key(parameters)
raise UnsupportedAlgorithm(
"This backend does not support Diffie-Hellman",
_Reasons.UNSUPPORTED_DIFFIE_HELLMAN
)
def load_dh_private_numbers(self, numbers):
for b in self._filtered_backends(DHBackend):
return b.load_dh_private_numbers(numbers)
raise UnsupportedAlgorithm(
"This backend does not support Diffie-Hellman",
_Reasons.UNSUPPORTED_DIFFIE_HELLMAN
)
def load_dh_public_numbers(self, numbers):
for b in self._filtered_backends(DHBackend):
return b.load_dh_public_numbers(numbers)
raise UnsupportedAlgorithm(
"This backend does not support Diffie-Hellman",
_Reasons.UNSUPPORTED_DIFFIE_HELLMAN
)
def generate_dh_private_key_and_parameters(self, generator, key_size):
for b in self._filtered_backends(DHBackend):
return b.generate_dh_private_key_and_parameters(generator,
key_size)
raise UnsupportedAlgorithm(
"This backend does not support Diffie-Hellman",
_Reasons.UNSUPPORTED_DIFFIE_HELLMAN
)
def dh_parameters_supported(self, p, g):
for b in self._filtered_backends(DHBackend):
return b.dh_parameters_supported(p, g)
raise UnsupportedAlgorithm(
"This backend does not support Diffie-Hellman",
_Reasons.UNSUPPORTED_DIFFIE_HELLMAN
)
def x509_name_bytes(self, name):
for b in self._filtered_backends(X509Backend):
return b.x509_name_bytes(name)
raise UnsupportedAlgorithm(
"This backend does not support X.509.",
_Reasons.UNSUPPORTED_X509
)
def derive_scrypt(self, key_material, salt, length, n, r, p):
for b in self._filtered_backends(ScryptBackend):
return b.derive_scrypt(key_material, salt, length, n, r, p)
raise UnsupportedAlgorithm("This backend does not support scrypt.")
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