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| Current File : //snap/core/17212/usr/lib/python3/dist-packages/cryptography/hazmat/backends/openssl/rsa.py |
# 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 math
from cryptography import utils
from cryptography.exceptions import (
AlreadyFinalized, InvalidSignature, UnsupportedAlgorithm, _Reasons
)
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import (
AsymmetricSignatureContext, AsymmetricVerificationContext, rsa
)
from cryptography.hazmat.primitives.asymmetric.padding import (
AsymmetricPadding, MGF1, OAEP, PKCS1v15, PSS
)
from cryptography.hazmat.primitives.asymmetric.rsa import (
RSAPrivateKeyWithSerialization, RSAPublicKeyWithSerialization
)
def _get_rsa_pss_salt_length(pss, key_size, digest_size):
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
def _enc_dec_rsa(backend, key, data, padding):
if not isinstance(padding, AsymmetricPadding):
raise TypeError("Padding must be an instance of AsymmetricPadding.")
if isinstance(padding, PKCS1v15):
padding_enum = backend._lib.RSA_PKCS1_PADDING
elif isinstance(padding, OAEP):
padding_enum = backend._lib.RSA_PKCS1_OAEP_PADDING
if not isinstance(padding._mgf, MGF1):
raise UnsupportedAlgorithm(
"Only MGF1 is supported by this backend.",
_Reasons.UNSUPPORTED_MGF
)
if not isinstance(padding._mgf._algorithm, hashes.SHA1):
raise UnsupportedAlgorithm(
"This backend supports only SHA1 inside MGF1 when "
"using OAEP.",
_Reasons.UNSUPPORTED_HASH
)
if padding._label is not None and padding._label != b"":
raise ValueError("This backend does not support OAEP labels.")
if not isinstance(padding._algorithm, hashes.SHA1):
raise UnsupportedAlgorithm(
"This backend only supports SHA1 when using OAEP.",
_Reasons.UNSUPPORTED_HASH
)
else:
raise UnsupportedAlgorithm(
"{0} is not supported by this backend.".format(
padding.name
),
_Reasons.UNSUPPORTED_PADDING
)
if backend._lib.Cryptography_HAS_PKEY_CTX:
return _enc_dec_rsa_pkey_ctx(backend, key, data, padding_enum)
else:
return _enc_dec_rsa_098(backend, key, data, padding_enum)
def _enc_dec_rsa_pkey_ctx(backend, key, data, padding_enum):
if isinstance(key, _RSAPublicKey):
init = backend._lib.EVP_PKEY_encrypt_init
crypt = backend._lib.Cryptography_EVP_PKEY_encrypt
else:
init = backend._lib.EVP_PKEY_decrypt_init
crypt = backend._lib.Cryptography_EVP_PKEY_decrypt
pkey_ctx = backend._lib.EVP_PKEY_CTX_new(
key._evp_pkey, backend._ffi.NULL
)
backend.openssl_assert(pkey_ctx != backend._ffi.NULL)
pkey_ctx = backend._ffi.gc(pkey_ctx, backend._lib.EVP_PKEY_CTX_free)
res = init(pkey_ctx)
backend.openssl_assert(res == 1)
res = backend._lib.EVP_PKEY_CTX_set_rsa_padding(
pkey_ctx, padding_enum)
backend.openssl_assert(res > 0)
buf_size = backend._lib.EVP_PKEY_size(key._evp_pkey)
backend.openssl_assert(buf_size > 0)
outlen = backend._ffi.new("size_t *", buf_size)
buf = backend._ffi.new("char[]", buf_size)
# Everything from this line onwards is written with the goal of being as
# constant-time as is practical given the constraints of Python and our
# API. See Bleichenbacher's '98 attack on RSA, and its many many variants.
# As such, you should not attempt to change this (particularly to "clean it
# up") without understanding why it was written this way (see
# Chesterton's Fence), and without measuring to verify you have not
# introduced observable time differences.
res = crypt(pkey_ctx, buf, outlen, data, len(data))
resbuf = backend._ffi.buffer(buf)[: outlen[0]]
backend._lib.ERR_clear_error()
if res <= 0:
raise ValueError("Encryption/decryption failed.")
return resbuf
def _enc_dec_rsa_098(backend, key, data, padding_enum):
if isinstance(key, _RSAPublicKey):
crypt = backend._lib.RSA_public_encrypt
else:
crypt = backend._lib.RSA_private_decrypt
key_size = backend._lib.RSA_size(key._rsa_cdata)
backend.openssl_assert(key_size > 0)
buf = backend._ffi.new("unsigned char[]", key_size)
res = crypt(len(data), data, buf, key._rsa_cdata, padding_enum)
if res < 0:
_handle_rsa_enc_dec_error(backend, key)
return backend._ffi.buffer(buf)[:res]
def _handle_rsa_enc_dec_error(backend, key):
errors = backend._consume_errors()
assert errors
assert errors[0].lib == backend._lib.ERR_LIB_RSA
if isinstance(key, _RSAPublicKey):
assert (errors[0].reason ==
backend._lib.RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE)
raise ValueError(
"Data too long for key size. Encrypt less data or use a "
"larger key size."
)
else:
decoding_errors = [
backend._lib.RSA_R_BLOCK_TYPE_IS_NOT_01,
backend._lib.RSA_R_BLOCK_TYPE_IS_NOT_02,
backend._lib.RSA_R_OAEP_DECODING_ERROR,
]
if backend._lib.Cryptography_HAS_RSA_R_PKCS_DECODING_ERROR:
decoding_errors.append(backend._lib.RSA_R_PKCS_DECODING_ERROR)
assert errors[0].reason in decoding_errors
raise ValueError("Decryption failed.")
@utils.register_interface(AsymmetricSignatureContext)
class _RSASignatureContext(object):
def __init__(self, backend, private_key, padding, algorithm):
self._backend = backend
self._private_key = private_key
if not isinstance(padding, AsymmetricPadding):
raise TypeError("Expected provider of AsymmetricPadding.")
self._pkey_size = self._backend._lib.EVP_PKEY_size(
self._private_key._evp_pkey
)
self._backend.openssl_assert(self._pkey_size > 0)
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)
if self._pkey_size - 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 = hashes.Hash(self._algorithm, self._backend)
def update(self, data):
self._hash_ctx.update(data)
def finalize(self):
evp_md = self._backend._lib.EVP_get_digestbyname(
self._algorithm.name.encode("ascii"))
self._backend.openssl_assert(evp_md != self._backend._ffi.NULL)
return self._finalize_method(evp_md)
def _finalize_pkey_ctx(self, evp_md):
pkey_ctx = self._backend._lib.EVP_PKEY_CTX_new(
self._private_key._evp_pkey, self._backend._ffi.NULL
)
self._backend.openssl_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)
self._backend.openssl_assert(res == 1)
res = self._backend._lib.EVP_PKEY_CTX_set_signature_md(
pkey_ctx, evp_md)
self._backend.openssl_assert(res > 0)
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_padding(
pkey_ctx, self._padding_enum)
self._backend.openssl_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
)
)
self._backend.openssl_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"))
self._backend.openssl_assert(
mgf1_md != self._backend._ffi.NULL
)
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_mgf1_md(
pkey_ctx, mgf1_md
)
self._backend.openssl_assert(res > 0)
data_to_sign = self._hash_ctx.finalize()
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)
)
self._backend.openssl_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.")
else:
assert (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_md):
if self._hash_ctx._ctx is None:
raise AlreadyFinalized("Context has already been finalized.")
sig_buf = self._backend._ffi.new("char[]", self._pkey_size)
sig_len = self._backend._ffi.new("unsigned int *")
res = self._backend._lib.EVP_SignFinal(
self._hash_ctx._ctx._ctx,
sig_buf,
sig_len,
self._private_key._evp_pkey
)
self._hash_ctx.finalize()
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_md):
data_to_sign = self._hash_ctx.finalize()
padded = self._backend._ffi.new("unsigned char[]", self._pkey_size)
res = self._backend._lib.RSA_padding_add_PKCS1_PSS(
self._private_key._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[]", self._pkey_size)
sig_len = self._backend._lib.RSA_private_encrypt(
self._pkey_size,
padded,
sig_buf,
self._private_key._rsa_cdata,
self._backend._lib.RSA_NO_PADDING
)
self._backend.openssl_assert(sig_len != -1)
return self._backend._ffi.buffer(sig_buf)[:sig_len]
@utils.register_interface(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, AsymmetricPadding):
raise TypeError("Expected provider of AsymmetricPadding.")
self._pkey_size = self._backend._lib.EVP_PKEY_size(
self._public_key._evp_pkey
)
self._backend.openssl_assert(self._pkey_size > 0)
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)
if self._pkey_size - 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 = hashes.Hash(self._algorithm, self._backend)
def update(self, data):
self._hash_ctx.update(data)
def verify(self):
evp_md = self._backend._lib.EVP_get_digestbyname(
self._algorithm.name.encode("ascii"))
self._backend.openssl_assert(evp_md != self._backend._ffi.NULL)
self._verify_method(evp_md)
def _verify_pkey_ctx(self, evp_md):
pkey_ctx = self._backend._lib.EVP_PKEY_CTX_new(
self._public_key._evp_pkey, self._backend._ffi.NULL
)
self._backend.openssl_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)
self._backend.openssl_assert(res == 1)
res = self._backend._lib.EVP_PKEY_CTX_set_signature_md(
pkey_ctx, evp_md)
self._backend.openssl_assert(res > 0)
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_padding(
pkey_ctx, self._padding_enum)
self._backend.openssl_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
)
)
self._backend.openssl_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"))
self._backend.openssl_assert(
mgf1_md != self._backend._ffi.NULL
)
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_mgf1_md(
pkey_ctx, mgf1_md
)
self._backend.openssl_assert(res > 0)
data_to_verify = self._hash_ctx.finalize()
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.
self._backend.openssl_assert(res >= 0)
if res == 0:
errors = self._backend._consume_errors()
assert errors
raise InvalidSignature
def _verify_pkcs1(self, evp_md):
if self._hash_ctx._ctx is None:
raise AlreadyFinalized("Context has already been finalized.")
res = self._backend._lib.EVP_VerifyFinal(
self._hash_ctx._ctx._ctx,
self._signature,
len(self._signature),
self._public_key._evp_pkey
)
self._hash_ctx.finalize()
# 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.
self._backend.openssl_assert(res >= 0)
if res == 0:
errors = self._backend._consume_errors()
assert errors
raise InvalidSignature
def _verify_pss(self, evp_md):
buf = self._backend._ffi.new("unsigned char[]", self._pkey_size)
res = self._backend._lib.RSA_public_decrypt(
len(self._signature),
self._signature,
buf,
self._public_key._rsa_cdata,
self._backend._lib.RSA_NO_PADDING
)
if res != self._pkey_size:
errors = self._backend._consume_errors()
assert errors
raise InvalidSignature
data_to_verify = self._hash_ctx.finalize()
res = self._backend._lib.RSA_verify_PKCS1_PSS(
self._public_key._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(RSAPrivateKeyWithSerialization)
class _RSAPrivateKey(object):
def __init__(self, backend, rsa_cdata, evp_pkey):
self._backend = backend
self._rsa_cdata = rsa_cdata
self._evp_pkey = evp_pkey
self._key_size = self._backend._lib.BN_num_bits(self._rsa_cdata.n)
key_size = utils.read_only_property("_key_size")
def signer(self, padding, algorithm):
return _RSASignatureContext(self._backend, self, padding, algorithm)
def decrypt(self, ciphertext, padding):
key_size_bytes = int(math.ceil(self.key_size / 8.0))
if key_size_bytes != len(ciphertext):
raise ValueError("Ciphertext length must be equal to key size.")
return _enc_dec_rsa(self._backend, self, ciphertext, padding)
def public_key(self):
ctx = self._backend._lib.RSA_new()
self._backend.openssl_assert(ctx != self._backend._ffi.NULL)
ctx = self._backend._ffi.gc(ctx, self._backend._lib.RSA_free)
ctx.e = self._backend._lib.BN_dup(self._rsa_cdata.e)
ctx.n = self._backend._lib.BN_dup(self._rsa_cdata.n)
res = self._backend._lib.RSA_blinding_on(ctx, self._backend._ffi.NULL)
self._backend.openssl_assert(res == 1)
evp_pkey = self._backend._rsa_cdata_to_evp_pkey(ctx)
return _RSAPublicKey(self._backend, ctx, evp_pkey)
def private_numbers(self):
return rsa.RSAPrivateNumbers(
p=self._backend._bn_to_int(self._rsa_cdata.p),
q=self._backend._bn_to_int(self._rsa_cdata.q),
d=self._backend._bn_to_int(self._rsa_cdata.d),
dmp1=self._backend._bn_to_int(self._rsa_cdata.dmp1),
dmq1=self._backend._bn_to_int(self._rsa_cdata.dmq1),
iqmp=self._backend._bn_to_int(self._rsa_cdata.iqmp),
public_numbers=rsa.RSAPublicNumbers(
e=self._backend._bn_to_int(self._rsa_cdata.e),
n=self._backend._bn_to_int(self._rsa_cdata.n),
)
)
def private_bytes(self, encoding, format, encryption_algorithm):
return self._backend._private_key_bytes(
encoding,
format,
encryption_algorithm,
self._evp_pkey,
self._rsa_cdata
)
@utils.register_interface(RSAPublicKeyWithSerialization)
class _RSAPublicKey(object):
def __init__(self, backend, rsa_cdata, evp_pkey):
self._backend = backend
self._rsa_cdata = rsa_cdata
self._evp_pkey = evp_pkey
self._key_size = self._backend._lib.BN_num_bits(self._rsa_cdata.n)
key_size = utils.read_only_property("_key_size")
def verifier(self, signature, padding, algorithm):
if not isinstance(signature, bytes):
raise TypeError("signature must be bytes.")
return _RSAVerificationContext(
self._backend, self, signature, padding, algorithm
)
def encrypt(self, plaintext, padding):
return _enc_dec_rsa(self._backend, self, plaintext, padding)
def public_numbers(self):
return rsa.RSAPublicNumbers(
e=self._backend._bn_to_int(self._rsa_cdata.e),
n=self._backend._bn_to_int(self._rsa_cdata.n),
)
def public_bytes(self, encoding, format):
return self._backend._public_key_bytes(
encoding,
format,
self._evp_pkey,
self._rsa_cdata
)
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