Hint
The deprecation warning emitted on import does not inherit :py:exc:`DeprecationWarning` but inherits :py:exc:`UserWarning` instead.
If your pytest setup follows the best practices of failing on
emitted warnings (filterwarnings = error), you may ignore it
by adding the following line at the end of the list:
ignore:Python 2 is no longer supported by the Python core team. Support for it is now deprecated in cryptography, and will be removed in a future release.:UserWarning
Note: Using cryptography.utils.CryptographyDeprecationWarning
is not possible here because specifying it triggers
import cryptography internally that emits the warning before
the ignore rule even kicks in.
The same applies when you use :py:func:`~warnings.filterwarnings` in your code or invoke CPython with :std:option:`-W` command line option.
If you are having issues installing cryptography the first troubleshooting
step is to upgrade pip and then try to install again. For most users this will
take the form of pip install -U pip, but on Windows you should do
python -m pip install -U pip. If you are still seeing errors after upgrading
and trying pip install cryptography again, please see the :doc:`/installation`
documentation.
While cryptography and NaCl both share the goal of making cryptography
easier, and safer, to use for developers, cryptography is designed to be a
general purpose library, interoperable with existing systems, while NaCl
features a collection of hand selected algorithms.
cryptography's :ref:`recipes <cryptography-layout>` layer has similar goals
to NaCl.
If you prefer NaCl's design, we highly recommend PyNaCl, which is also maintained by the PyCA team.
If you've done cryptographic work in Python before you have likely encountered
other libraries in Python such as M2Crypto, PyCrypto, or PyOpenSSL. In
building cryptography we wanted to address a few issues we observed in the
legacy libraries:
- Extremely error prone APIs and insecure defaults.
- Use of poor implementations of algorithms (i.e. ones with known side-channel attacks).
- Lack of maintenance.
- Lack of high level APIs.
- Lack of PyPy and Python 3 support.
- Absence of algorithms such as :class:`AES-GCM <cryptography.hazmat.primitives.ciphers.modes.GCM>` and :class:`~cryptography.hazmat.primitives.kdf.hkdf.HKDF`.
cryptography provides wheels which include a statically linked copy of
OpenSSL. If you see this error it is likely because your copy of pip is too
old to find our wheel files. Upgrade your pip with pip install -U pip
and then try to install cryptography again.
Users on PyPy, unusual CPU architectures, or distributions of Linux using
musl (like Alpine) will need to compile cryptography themselves. Please
view our :doc:`/installation` documentation.
Frequently InternalError is raised when there are errors on the OpenSSL
error stack that were placed there by other libraries that are also using
OpenSSL. Try removing the other libraries and see if the problem persists.
If you have no other libraries using OpenSSL in your process, or they do not
appear to be at fault, it's possible that this is a bug in cryptography.
Please file an issue with instructions on how to reproduce it.
The compiler you are using is too old and not supported by cryptography.
Please upgrade to a more recent version. If you are running OpenBSD 6.1 or
earlier the default compiler is extremely old. Use pkg_add to install a
newer gcc and then install cryptography using
CC=/path/to/newer/gcc pip install cryptography.
Your pip and/or setuptools are outdated. Please upgrade to the latest
versions with pip install -U pip setuptools (or on Windows
python -m pip install -U pip setuptools).
The OpenSSL project has dropped support for the 0.9.8, 1.0.0, 1.0.1, and 1.0.2
release series. Since they are no longer receiving security patches from
upstream, cryptography is also dropping support for them. To fix this issue
you should upgrade to a newer version of OpenSSL (1.1.0 or later). This may
require you to upgrade to a newer operating system.
Building cryptography from source requires you have :ref:`Rust installed
and available<installation:Rust>` on your PATH. You may be able to fix this
by upgrading to a newer version of pip which will install a pre-compiled
cryptography wheel. If not, you'll need to install Rust. Follow the
:ref:`instructions<installation:Rust>` to ensure you install a recent Rust
version.
Rust is only required during the build phase of cryptography, you do not
need to have Rust installed after you've built cryptography. This is the
same as the C compiler toolchain which is also required to build
cryptography, but not afterwards.
Our Python3 wheels are abi3 wheels. This means they support multiple
versions of Python. The abi3 wheel can be used with any version of Python
greater than or equal to the version it specifies. Recent versions of pip
will automatically install abi3 wheels.
PEM is a format (defined by several RFCs, but originally RFC 1421) for encoding keys, certificates and others cryptographic data into a regular form. The data is encoded as base64 and wrapped with a header and footer.
If you are having trouble importing PEM files, make sure your file fits the following rules:
- has a one-line header like this:
-----BEGIN [FILE TYPE]-----(where[FILE TYPE]isCERTIFICATE,PUBLIC KEY,PRIVATE KEY, etc.) - has a one-line footer like this:
-----END [FILE TYPE]----- - all lines, except for the final one, must consist of exactly 64 characters.
For example, this is a PEM file for a RSA Public Key:
-----BEGIN PUBLIC KEY----- MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA7CsKFSzq20NLb2VQDXma 9DsDXtKADv0ziI5hT1KG6Bex5seE9pUoEcUxNv4uXo2jzAUgyRweRl/DLU8SoN8+ WWd6YWik4GZvNv7j0z28h9Q5jRySxy4dmElFtIRHGiKhqd1Z06z4AzrmKEzgxkOk LJjY9cvwD+iXjpK2oJwNNyavvjb5YZq6V60RhpyNtKpMh2+zRLgIk9sROEPQeYfK 22zj2CnGBMg5Gm2uPOsGDltl/I/Fdh1aO3X4i1GXwCuPf1kSAg6lPJD0batftkSG v0X0heUaV0j1HSNlBWamT4IR9+iJfKJHekOqvHQBcaCu7Ja4kXzx6GZ3M2j/Ja3A 2QIDAQAB -----END PUBLIC KEY-----