load_pem_private_key fails with unexpected OpenSSL error depending on password #8563
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lukpueh
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Mar 22, 2023
Every now and then this test fails, because pyca/cryptography raises an unexpected error message (see pyca/cryptography#8563) Regardless of whether it is a good idea to assert error messages of 3rd party libraries, this patch provides a quick fix by asserting that is one of both known error messages. closes secure-systems-lab#463 Signed-off-by: Lukas Puehringer <[email protected]>
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Unfortunately because PEM encryption is not authenticated, decryption can
produce all sorts of invalid keys, we do not know if's because the password
is wrong or because the decrypted contents was malformed.
…On Wed, Mar 22, 2023 at 7:25 AM Lukas Pühringer ***@***.***> wrote:
I have a test that creates an encrypted rsa key and then tries to load and
decrypt it with load_pem_private_key, using an invalid password and
asserting the error message "Bad decrypt. Incorrect password?".
Every now and then my test fails, because I get a different error message,
i.e.: (pretty printed for better readability)
('Could not deserialize key data. The data may be in an incorrect format, it '
'may be encrypted with an unsupported algorithm, or it may be an unsupported '
'key type (e.g. EC curves with explicit parameters).',
[_OpenSSLErrorWithText(code=503841036, lib=60, reason=524556, reason_text=b'error:1E08010C:DECODER routines::unsupported'),
_OpenSSLErrorWithText(code=109052027, lib=13, reason=123, reason_text=b'error:0680007B:asn1 encoding routines::header too long'),
_OpenSSLErrorWithText(code=109052006, lib=13, reason=102, reason_text=b'error:06800066:asn1 encoding routines::bad object header'),
_OpenSSLErrorWithText(code=109576458, lib=13, reason=524554, reason_text=b'error:0688010A:asn1 encoding routines::nested asn1 error'),
_OpenSSLErrorWithText(code=109052027, lib=13, reason=123, reason_text=b'error:0680007B:asn1 encoding routines::header too long'),
_OpenSSLErrorWithText(code=109052006, lib=13, reason=102, reason_text=b'error:06800066:asn1 encoding routines::bad object header'),
_OpenSSLErrorWithText(code=109576458, lib=13, reason=524554, reason_text=b'error:0688010A:asn1 encoding routines::nested asn1 error')])
The key parses successfully when providing the correct password, and also
raises the expected error when providing a different invalid password.
The following script can be used to reproduce the issue. Key is
hard-coded, because the issue does not occur for every key created with the
commented out snippet.
*Reproducer*
from cryptography.hazmat.primitives.serialization import load_pem_private_key
# # Create encrypted RSA PEM# from cryptography.hazmat.backends import default_backend# from cryptography.hazmat.primitives import serialization# from cryptography.hazmat.primitives.asymmetric import rsa## key = rsa.generate_private_key(# public_exponent=65537, key_size=3072, backend=default_backend()# )# encrypted_rsa_key = key.private_bytes(# encoding=serialization.Encoding.PEM,# format=serialization.PrivateFormat.TraditionalOpenSSL,# encryption_algorithm=serialization.BestAvailableEncryption(b"pw"),# )
# Not every key triggers the unexpected error below, but this one does:encrypted_rsa_key = b"-----BEGIN RSA PRIVATE KEY-----\nProc-Type: 4,ENCRYPTED\nDEK-Info: AES-256-CBC,6EF2C95AF143341584114A13ED0A8C06\n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\n-----END RSA PRIVATE KEY-----"
# Parse and decrypt successfully with valid passwordload_pem_private_key(encrypted_rsa_key, b"pw")
# Fail with invalid password and expected error message: "Bad decrypt. Incorrect password?"load_pem_private_key(encrypted_rsa_key, b"not pw")
# Fail with different invalid password and unexpected error message: "Could not deserialize key data..."load_pem_private_key(encrypted_rsa_key, b"bad pw")
*Environment*
$ python --version
Python 3.10.9
$ pip list
Package Version
------------ -------
cffi 1.15.1
cryptography 39.0.2
pip 23.0.1
pycparser 2.21
setuptools 67.4.0
wheel 0.38.4
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Makes sense. Thanks for the quick reply! Feel free to close the issue. |
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Sorry we don't hvae a happier answer. |
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I have a test that creates an encrypted rsa key and then tries to load and decrypt it with
load_pem_private_key, using an invalid password and asserting the error message"Bad decrypt. Incorrect password?".Every now and then my test fails, because I get a different error message, i.e.: (pretty printed for better readability)
The key parses successfully when providing the correct password, and also raises the expected error when providing a different invalid password.
The following script can be used to reproduce the issue. Key is hard-coded, because the issue does not occur for every key created with the commented out snippet.
Reproducer
Environment
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