Bump cryptography from 2.9.2 to 3.0

[dependabot-preview]

Bumps cryptography from 2.9.2 to 3.0.

Changelog

Sourced from cryptography's changelog.

3.0 - 2020-07-20

• BACKWARDS INCOMPATIBLE: Removed support for passing an ~cryptography.x509.Extension instance to ~cryptography.x509.AuthorityKeyIdentifier.from_issuer_subject_key_identifier, as per our deprecation policy.
• BACKWARDS INCOMPATIBLE: Support for LibreSSL 2.7.x, 2.8.x, and 2.9.0 has been removed (2.9.1+ is still supported).
• BACKWARDS INCOMPATIBLE: Dropped support for macOS 10.9, macOS users must upgrade to 10.10 or newer.
• BACKWARDS INCOMPATIBLE: RSA ~cryptography.hazmat.primitives.asymmetric.rsa.generate_private_key no longer accepts public_exponent values except 65537 and 3 (the latter for legacy purposes).
• BACKWARDS INCOMPATIBLE: X.509 certificate parsing now enforces that the version field contains a valid value, rather than deferring this check until ~cryptography.x509.Certificate.version is accessed.
• Deprecated support for Python 2. At the time there is no time table for actually dropping support, however we strongly encourage all users to upgrade their Python, as Python 2 no longer receives support from the Python core team.
• Added support for OpenSSH serialization format for ec, ed25519, rsa and dsa private keys: ~cryptography.hazmat.primitives.serialization.load_ssh_private_key for loading and ~cryptography.hazmat.primitives.serialization.PrivateFormat.OpenSSH for writing.
• Added support for OpenSSH certificates to ~cryptography.hazmat.primitives.serialization.load_ssh_public_key.
• Added ~cryptography.fernet.Fernet.encrypt_at_time and ~cryptography.fernet.Fernet.decrypt_at_time to ~cryptography.fernet.Fernet.
• Added support for the ~cryptography.x509.SubjectInformationAccess X.509 extension.
• Added support for parsing ~cryptography.x509.SignedCertificateTimestamps in OCSP responses.
• Added support for parsing attributes in certificate signing requests via ~cryptography.x509.CertificateSigningRequest.get_attribute_for_oid.
• Added support for encoding attributes in certificate signing requests via ~cryptography.x509.CertificateSigningRequestBuilder.add_attribute.
• On OpenSSL 1.1.1d and higher cryptography now uses OpenSSL's built-in CSPRNG instead of its own OS random engine because these versions of OpenSSL properly reseed on fork.
• Added initial support for creating PKCS12 files with ~cryptography.hazmat.primitives.serialization.pkcs12.serialize_key_and_certificates.

Commits

• b0d9bdc prep 3.0 for release (#5327)
• 6bd3faa Tell people to use black in our dev docs (#5328)
• 60aa044 Paint it Black by the Rolling Stones (#5324)
• 4a245a6 test FIPS mode on centos8 (#5323)
• 2fdb747 PKCS12 support (#5325)
• 972c886 refactor DH a bit to generate less parameters (#5326)
• 31359f3 fix grammar in error message (#5322)
• 084da16 disable the osrandom engine on 1.1.1d+ (#5317)
• 1604ea7 test exceptions and properly reject duplicate attributes in csrbuilder (#5319)
• b8656fc Implement deepcopy for x509 certificates (#5318)
• Additional commits viewable in compare view

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[coveralls]

Coverage decreased (-98.9%) to 0.0% when pulling 84b8e65 on dependabot/pip/cryptography-3.0 into bdcd1b4 on master.

[joshuagl]

The tests are failing and claiming we're trying to load a DSA key that has fewer than 1024 bits:

ERROR: test_export_pubkey (tests.test_gpg.TestGPGDSA)
export a public key and make sure the parameters are the right ones:
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/travis/build/secure-systems-lab/securesystemslib/tests/test_gpg.py", line 674, in test_export_pubkey
backends.default_backend())
File "/home/travis/build/secure-systems-lab/securesystemslib/.tox/py37/lib/python3.7/site-packages/cryptography/hazmat/primitives/serialization/ssh.py", line 655, in load_ssh_public_key
public_key, data = kformat.load_public(key_type, data, backend)
File "/home/travis/build/secure-systems-lab/securesystemslib/.tox/py37/lib/python3.7/site-packages/cryptography/hazmat/primitives/serialization/ssh.py", line 296, in load_public
self._validate(public_numbers)
File "/home/travis/build/secure-systems-lab/securesystemslib/.tox/py37/lib/python3.7/site-packages/cryptography/hazmat/primitives/serialization/ssh.py", line 333, in _validate
raise ValueError("SSH supports only 1024 bit DSA keys")
ValueError: SSH supports only 1024 bit DSA keys

however if I look at the test keys with ssh-keygen -l I'm told they are each 2048 bit keys:

% for i in find . -name \*.ssh; do ssh-keygen -l -f $i; done
2048 SHA256:zbkcf58RkXlB4bYQreWUOxR9sV8p+nNOwtL4QCcOh4s openpgp:0xB285DA58 (RSA)
2048 SHA256:q2Y8RIW7I1ZlHxPvwtBwbQhzvMyf47HG9gjDx/paOnc openpgp:0x7E0C8A17 (RSA)
2048 SHA256:FkuEdY2ujYlqWZiVOY4JO/C8cghzLuG751MlNfkkcSs openpgp:0x1C768C43 (RSA)
2048 SHA256:ZtTwtYC06hyQMoxeL0qxVjxj1lBDavMSt3hdWk67WZU openpgp:0xE267B3B1 (DSA)

[lukpueh]

It actually doesn't claim that our key has fewer than 1024 bits, but rather that it doesn't have exactly 1024 bits. The restriction was added in pyca/cryptography#5146 and released with 3.0, without any mention of it in the changelog or corresponding commit/PR.

I'm not sure why though, because we were able to load the 2048 bit pub key just fine before. I think I'll open an issue on pyca/cryptography.

[lukpueh]

So it seems the restriction was indeed intended (see pyca/cryptography#5373). The easiest thing to fix this will be to just store the test key in another format, e.g. PEM.

[trishankatdatadog]

The easiest thing to fix this will be to just store the test key in another format, e.g. PEM.

We have a few other options, no?

• Downgrade the keys to 1024 bits.
• Remove support for DSA. Do we really need it?

[lukpueh]

We have a few other options, no?

• Downgrade the keys to 1024 bits.
• Remove support for DSA. Do we really need it?

Good point. I thought about those too, but decided against them because, downgrading (replacing) the key in the test gpg keychain would have been more work than just changing the format of the pubkey file, and removing DSA support is a bigger decision that I didn't see the need for to make right now.
But yeah, it seems like pyca/cryptography will deprecate DSA at some point and then it might not be worth the effort to find a an alternative crypto library so that we can continue support.

#264 has my PEM fix and successfully tests against cryptography==3.0.

[dependabot-preview]

Looks like cryptography is up-to-date now, so this is no longer needed.