安装cryptography报错 Failed to build cryptography

[Irek_xu]

命令：env CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1 LDFLAGS="$(brew --prefix openssl@1.1)/lib/libssl.a $(brew --prefix openssl@1.1)/lib/libcrypto.a" CFLAGS="-I$(brew --prefix openssl@1.1)/include" pip3 install cryptography

报错：
Collecting cryptography
Using cached https://files.pythonhosted.org/packages/a3/5f/d5b7d21006e3c1a3919a3cc14e2a5ce1cee1c7ff635f09b31d91bdaff377/cryptography-2.6.tar.gz
Installing build dependencies ... done
Getting requirements to build wheel ... done
Preparing wheel metadata ... done
Collecting asn1crypto>=0.21.0 (from cryptography)
Using cached https://files.pythonhosted.org/packages/ea/cd/35485615f45f30a510576f1a56d1e0a7ad7bd8ab5ed7cdc600ef7cd06222/asn1crypto-0.24.0-py2.py3-none-any.whl
Collecting cffi!=1.11.3,>=1.8 (from cryptography)
Using cached https://files.pythonhosted.org/packages/6b/af/e39e89ecbfb676c6aa5855b1795bb207f4005187495c8d40e26b5fb51bfa/cffi-1.12.2-cp37-cp37m-macosx_10_9_x86_64.whl
Requirement already satisfied: six>=1.4.1 in /Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages (from cryptography) (1.11.0)
Requirement already satisfied: pycparser in /Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages (from cffi!=1.11.3,>=1.8->cryptography) (2.19)
Building wheels for collected packages: cryptography
Building wheel for cryptography (PEP 517) ... done
Running setup.py clean for cryptography
Failed to build cryptography
Could not build wheels for cryptography which use PEP 517 and cannot be installed directly

[h50327692]

Easy, try to run this:

pip install pep517

And then try to install again

python3 -m pip install cryptography