如何解决pqcrypto库导入失败及安装构建问题？

环境信息 #

• VirtualBox中运行Ubuntu 22.04
• Python 3.10.6
• Pip 23.0.1

问题详情 #

尝试使用pqcrypto库时，Pylance提示：

Import "pqcrypto" could not be resolved Pylance (reportMissingImports)

最初执行pip install pqcrypto安装时，wheel构建失败，核心错误为cffi版本不匹配：

Exception: Version mismatch: this is the 'cffi' package version 1.15.1, located in '/tmp/pip-build-env-ifogc2y8/overlay/local/lib/python3.10/dist-packages/cffi/api.py'.  When we import the top-level '_cffi_backend' extension module, we get version 1.15.0, located in '/usr/lib/python3/dist-packages/_cffi_backend.cpython-310-x86_64-linux-gnu.so'.  The two versions should be equal; check your installation.

之后下载源码包执行sudo python setup.py install，安装完成后pip install pqcrypto显示已安装：

$ pip install pqcrypto
Requirement already satisfied: pqcrypto in /home/mack/Desktop/RSAvsCK/venv/lib/python3.10/site-packages/pqcrypto-0.1.3-py3.10-linux-x86_64.egg (0.1.3)
Requirement already satisfied: cffi<2.0.0,>=1.14.2 in ./.eggs/cffi-1.15.1-py3.10-linux-x86_64.egg (from pqcrypto) (1.15.1)
Requirement already satisfied: pycparser in ./.eggs/pycparser-2.21-py3.10.egg (from cffi<2.0.0,>=1.14.2->pqcrypto) (2.21)

pip show pqcrypto也能正常读取库信息：

$ pip show pqcrypto
Name: pqcrypto
Version: 0.1.3
Summary: Post-quantum cryptography for Python.
Home-page: https://github.com/kpdemetriou/pqcrypto
Author: Phil Demetriou
Author-email: inbox@philonas.net
License: 
Location: /home/mack/Desktop/RSAvsCK/venv/lib/python3.10/site-packages/pqcrypto-0.1.3-py3.10-linux-x86_64.egg
Requires: cffi
Required-by: 

已在虚拟环境内外尝试操作，但导入失败问题仍未解决。

解决方案 #

1. 修复cffi版本不匹配问题

wheel构建失败的根源是系统全局_cffi_backend版本与临时安装的cffi版本不一致，先统一版本：

# 卸载全局和虚拟环境中的cffi
sudo pip3 uninstall -y cffi
pip uninstall -y cffi

# 安装与系统后端匹配的版本
sudo pip3 install cffi==1.15.0
# 激活虚拟环境后执行
pip install cffi==1.15.0

2. 重新正确安装pqcrypto

避免使用sudo python setup.py install（会导致权限和虚拟环境路径冲突），激活虚拟环境后重新安装：

# 激活虚拟环境
source /home/mack/Desktop/RSAvsCK/venv/bin/activate

# 卸载已安装的pqcrypto
pip uninstall -y pqcrypto

# 重新用pip安装（此时cffi版本匹配，wheel可正常构建）
pip install pqcrypto

# 若仍失败，在虚拟环境内用源码安装（不要加sudo）
cd pqcrypto源码目录
python setup.py install

3. 让Pylance识别虚拟环境

• 在VS Code中按Ctrl+Shift+P，选择Python: Select Interpreter，选中虚拟环境路径/home/mack/Desktop/RSAvsCK/venv/bin/python
• 等待Pylance重新索引，若仍报错则重启VS Code
• 检查.vscode/settings.json，确保python.pythonPath指向虚拟环境的Python解释器

4. 验证导入可用性

直接运行Python脚本测试，排除Pylance索引问题：

import pqcrypto
print(pqcrypto.__version__)

若运行无报错，说明是Pylance索引问题，按步骤3操作即可；若运行报错，检查虚拟环境是否激活、site-packages路径是否正确。

内容的提问来源于stack exchange，提问作者Mack Osborne