为什么安装密码学 python package 失败？

Question

我正在尝试在 Python 中安装 package 加密，但每次尝试它都会失败并出现错误。
我用来安装这个 package 的命令是： pip install cryptography==2.8
我得到的错误如下：

Collecting cryptography==2.8
Using cached cryptography-2.8.tar.gz (504 kB)
Installing build dependencies ... done
Getting requirements to build wheel ... done
Preparing wheel metadata ... done
Requirement already satisfied: cffi!=1.11.3,>=1.8 in c:\users\abcd\appdata\local\programs\python\python39\lib\site-packages (from cryptography==2.8) (1.14.5)
Requirement already satisfied: six>=1.4.1 in c:\users\abcd\appdata\local\programs\python\python39\lib\site-packages (from cryptography==2.8) (1.15.0)
Requirement already satisfied: pycparser in c:\users\abcd\appdata\local\programs\python\python39\lib\site-packages (from cffi!=1.11.3,>=1.8->cryptography==2.8) (2.20) 
Building wheels for collected packages: cryptography
Building wheel for cryptography (PEP 517) ... error
ERROR: Command errored out with exit status 1:
command: 'c:\users\abcd\appdata\local\programs\python\python39\python.exe' 'c:\users\abcd\appdata\local\programs\python\python39\lib\site-packages\pip\_vendor\pep517\_in_process.py' build_wheel 'C:\Users\abcd\AppData\Local\Temp\tmply9tk3q1'
cwd: C:\Users\abcd\AppData\Local\Temp\pip-install-hespmf8p\cryptography_59cf671691e246028ecf9a6a37f5e88c
Complete output (137 lines):
running bdist_wheel
running build
running build_py
creating build
creating build\lib.win-amd64-3.9
creating build\lib.win-amd64-3.9\cryptography
copying src\cryptography\exceptions.py -> build\lib.win-amd64-3.9\cryptography
copying src\cryptography\fernet.py -> build\lib.win-amd64-3.9\cryptography
copying src\cryptography\utils.py -> build\lib.win-amd64-3.9\cryptography
copying src\cryptography\__about__.py -> build\lib.win-amd64-3.9\cryptography
copying src\cryptography\__init__.py -> build\lib.win-amd64-3.9\cryptography
creating build\lib.win-amd64-3.9\cryptography\hazmat
copying src\cryptography\hazmat\_der.py -> build\lib.win-amd64-3.9\cryptography\hazmat
copying src\cryptography\hazmat\_oid.py -> build\lib.win-amd64-3.9\cryptography\hazmat
copying src\cryptography\hazmat\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat
creating build\lib.win-amd64-3.9\cryptography\x509
copying src\cryptography\x509\base.py -> build\lib.win-amd64-3.9\cryptography\x509
copying src\cryptography\x509\certificate_transparency.py -> build\lib.win-amd64-3.9\cryptography\x509
copying src\cryptography\x509\extensions.py -> build\lib.win-amd64-3.9\cryptography\x509
copying src\cryptography\x509\general_name.py -> build\lib.win-amd64-3.9\cryptography\x509
copying src\cryptography\x509\name.py -> build\lib.win-amd64-3.9\cryptography\x509
copying src\cryptography\x509\ocsp.py -> build\lib.win-amd64-3.9\cryptography\x509
copying src\cryptography\x509\oid.py -> build\lib.win-amd64-3.9\cryptography\x509
copying src\cryptography\x509\__init__.py -> build\lib.win-amd64-3.9\cryptography\x509
creating build\lib.win-amd64-3.9\cryptography\hazmat\backends
copying src\cryptography\hazmat\backends\interfaces.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends
copying src\cryptography\hazmat\backends\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends
creating build\lib.win-amd64-3.9\cryptography\hazmat\bindings
copying src\cryptography\hazmat\bindings\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\bindings
creating build\lib.win-amd64-3.9\cryptography\hazmat\primitives
copying src\cryptography\hazmat\primitives\cmac.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives
copying src\cryptography\hazmat\primitives\constant_time.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives
copying src\cryptography\hazmat\primitives\hashes.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives
copying src\cryptography\hazmat\primitives\hmac.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives
copying src\cryptography\hazmat\primitives\keywrap.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives
copying src\cryptography\hazmat\primitives\padding.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives
copying src\cryptography\hazmat\primitives\poly1305.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives
copying src\cryptography\hazmat\primitives\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives
creating build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\aead.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\backend.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\ciphers.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\cmac.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\decode_asn1.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\dh.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\dsa.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\ec.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\ed25519.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\ed448.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\encode_asn1.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\hashes.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\hmac.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\ocsp.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\poly1305.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\rsa.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\utils.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\x25519.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\x448.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\x509.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
copying src\cryptography\hazmat\backends\openssl\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\backends\openssl
creating build\lib.win-amd64-3.9\cryptography\hazmat\bindings\openssl
copying src\cryptography\hazmat\bindings\openssl\binding.py -> build\lib.win-amd64-3.9\cryptography\hazmat\bindings\openssl
copying src\cryptography\hazmat\bindings\openssl\_conditional.py -> build\lib.win-amd64-3.9\cryptography\hazmat\bindings\openssl
copying src\cryptography\hazmat\bindings\openssl\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\bindings\openssl
creating build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\dh.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\dsa.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\ec.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\ed25519.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\ed448.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\padding.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\rsa.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\utils.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\x25519.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\x448.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
copying src\cryptography\hazmat\primitives\asymmetric\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\asymmetric
creating build\lib.win-amd64-3.9\cryptography\hazmat\primitives\ciphers
copying src\cryptography\hazmat\primitives\ciphers\aead.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\ciphers
copying src\cryptography\hazmat\primitives\ciphers\algorithms.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\ciphers
copying src\cryptography\hazmat\primitives\ciphers\base.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\ciphers
copying src\cryptography\hazmat\primitives\ciphers\modes.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\ciphers
copying src\cryptography\hazmat\primitives\ciphers\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\ciphers
creating build\lib.win-amd64-3.9\cryptography\hazmat\primitives\kdf
copying src\cryptography\hazmat\primitives\kdf\concatkdf.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\kdf
copying src\cryptography\hazmat\primitives\kdf\hkdf.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\kdf
copying src\cryptography\hazmat\primitives\kdf\kbkdf.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\kdf
copying src\cryptography\hazmat\primitives\kdf\pbkdf2.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\kdf
copying src\cryptography\hazmat\primitives\kdf\scrypt.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\kdf
copying src\cryptography\hazmat\primitives\kdf\x963kdf.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\kdf
copying src\cryptography\hazmat\primitives\kdf\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\kdf
creating build\lib.win-amd64-3.9\cryptography\hazmat\primitives\serialization
copying src\cryptography\hazmat\primitives\serialization\base.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\serialization
copying src\cryptography\hazmat\primitives\serialization\pkcs12.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\serialization
copying src\cryptography\hazmat\primitives\serialization\ssh.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\serialization
copying src\cryptography\hazmat\primitives\serialization\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\serialization
creating build\lib.win-amd64-3.9\cryptography\hazmat\primitives\twofactor
copying src\cryptography\hazmat\primitives\twofactor\hotp.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\twofactor
copying src\cryptography\hazmat\primitives\twofactor\totp.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\twofactor
copying src\cryptography\hazmat\primitives\twofactor\utils.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\twofactor
copying src\cryptography\hazmat\primitives\twofactor\__init__.py -> build\lib.win-amd64-3.9\cryptography\hazmat\primitives\twofactor
running egg_info
writing src\cryptography.egg-info\PKG-INFO
writing dependency_links to src\cryptography.egg-info\dependency_links.txt
writing requirements to src\cryptography.egg-info\requires.txt
writing top-level names to src\cryptography.egg-info\top_level.txt
reading manifest file 'src\cryptography.egg-info\SOURCES.txt'
reading manifest template 'MANIFEST.in'
no previously-included directories found matching 'docs\_build'
warning: no previously-included files found matching 'vectors'
warning: no previously-included files matching '*' found under directory 'vectors'
warning: no previously-included files found matching 'azure-pipelines.yml'
warning: no previously-included files found matching '.azure-pipelines'
warning: no previously-included files found matching '.travis.yml'
warning: no previously-included files found matching '.travis'
warning: no previously-included files matching '*' found under directory '.azure-pipelines'
warning: no previously-included files matching '*' found under directory '.travis'
warning: no previously-included files found matching 'release.py'
warning: no previously-included files found matching '.coveragerc'
warning: no previously-included files found matching 'codecov.yml'
warning: no previously-included files found matching 'dev-requirements.txt'
warning: no previously-included files found matching 'rtd-requirements.txt'
warning: no previously-included files found matching 'tox.ini'
writing manifest file 'src\cryptography.egg-info\SOURCES.txt'
running build_ext
generating cffi module 'build\\temp.win-amd64-3.9\\Release\\_padding.c'
creating build\temp.win-amd64-3.9
creating build\temp.win-amd64-3.9\Release
generating cffi module 'build\\temp.win-amd64-3.9\\Release\\_constant_time.c'
generating cffi module 'build\\temp.win-amd64-3.9\\Release\\_openssl.c'
building '_openssl' extension
creating build\temp.win-amd64-3.9\Release\build
creating build\temp.win-amd64-3.9\Release\build\temp.win-amd64-3.9
creating build\temp.win-amd64-3.9\Release\build\temp.win-amd64-3.9\Release
C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.28.29910\bin\HostX86\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -Ic:\users\abcd\appdata\local\programs\python\python39\include -Ic:\users\abcd\appdata\local\programs\python\python39\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.28.29910\ATLMFC\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.28.29910\include -IC:\Program Files (x86)\Windows Kits\NETFXSDK\4.8\include\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared -IC:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\winrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\cppwinrt /Tcbuild\temp.win-amd64-3.9\Release\_openssl.c /Fobuild\temp.win-amd64-3.9\Release\build\temp.win-amd64-3.9\Release\_openssl.obj   
_openssl.c
build\temp.win-amd64-3.9\Release\_openssl.c(575): fatal error C1083: Cannot open include file: 'openssl/opensslv.h': No such file or directory
error: command 'C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Enterprise\\VC\\Tools\\MSVC\\14.28.29910\\bin\\HostX86\\x64\\cl.exe' failed with exit code 2    
----------------------------------------
ERROR: Failed building wheel for cryptography
Failed to build cryptography
ERROR: Could not build wheels for cryptography which use PEP 517 and cannot be installed directly

不知道这里可能出了什么问题。 早些时候我得到了一些与 Wheely package 相关的东西，所以我安装了 package 并且在它抛出这个错误之后。
我是 Python 的新手，我来自.Net 背景，因此在处理 Python 包时遇到困难。
任何帮助表示赞赏。 我什至尝试安装 OpenSSL 但它似乎没有用，或者我在这里遗漏了一些东西。

Answer 1

cryptography在 Windows 上提供二进制轮，因此用户无需编译，但您尝试安装的版本 (2.8) 没有适用于 Python 3.9 的轮。 如果您可以使用较新的版本，那么这将解决问题（尽管还要确保您升级到最新的pip 。）。