Frequently asked questions¶
cryptography
failed to install!¶
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 Installation
documentation.
How does cryptography
compare to NaCl (Networking and Cryptography Library)?¶
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 recipes layer has similar goals
to NaCl.
If you prefer NaCl’s design, we highly recommend PyNaCl, which is also maintained by the PyCA team.
Why use cryptography
?¶
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:
Compiling cryptography
on macOS produces a fatal error: 'openssl/aes.h' file not found
error¶
This happens because macOS 10.11 no longer includes a copy of OpenSSL.
cryptography
now provides wheels which include a statically linked copy of
OpenSSL. You’re seeing this error because your copy of pip is too old to find
our wheel files. Upgrade your copy of pip with pip install -U pip
and then
try install cryptography
again.
If you are using PyPy, we do not currently ship cryptography
wheels for
PyPy. You will need to install your own copy of OpenSSL – we recommend using
Homebrew.
cryptography
raised an InternalError
and I’m not sure what to do?¶
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.
error: -Werror=sign-conversion
: No option -Wsign-conversion
during installation¶
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
.
Installing cryptography
fails with Invalid environment marker: python_version < '3'
¶
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
).
Importing cryptography causes a RuntimeError
about OpenSSL 1.0.1¶
The OpenSSL project has dropped support for the 1.0.1 release series. Since it
is no longer receiving security patches from upstream, cryptography
is also
dropping support for it. To fix this issue you should upgrade to a newer
version of OpenSSL (1.0.2 or later). This may require you to upgrade to a newer
operating system.
For the 2.9 release, you can set the CRYPTOGRAPHY_ALLOW_OPENSSL_101
environment variable. Please note that this is temporary and will be removed
in cryptography
3.0.
Installing cryptography with OpenSSL 0.9.8 or 1.0.0 fails¶
The OpenSSL project has dropped support for the 0.9.8 and 1.0.0 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 (1.0.2 or later). This may require
you to upgrade to a newer operating system.
Why are there no wheels for Python 3.6+ on Linux or macOS?¶
Our Python3 wheels, for macOS and Linux, are abi3
wheels. This means they
support multiple versions of Python. The Python 3.5 abi3
wheel can be used
with any version of Python greater than or equal to 3.5. Recent versions of
pip
will automatically install abi3
wheels.
ImportError
: idna
is not installed¶
cryptography
deprecated passing U-label strings to various X.509
constructors in version 2.1 and in version 2.5 moved the idna
dependency
to a setuptools
extra. If you see this exception you should upgrade your
software so that it no longer depends on this deprecated feature. If that is
not yet possible you can also install cryptography
with
pip install cryptography[idna]
to automatically install the missing
dependency. This workaround will be available until the feature is fully
removed.
Why can’t I import my PEM file?¶
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-----