pip3 install -U cryptography
Collecting cryptography
  Downloading cryptography-3.4.3-cp36-abi3-manylinux2014_x86_64.whl (3.2 MB)
     |████████████████████████████████| 3.2 MB 5.3 MB/s 


python3 gencrypto.py

Traceback (most recent call last):
  File "gencrypto.py", line 2, in <module>
    from cryptography.hazmat.primitives.asymmetric import dh
  File "/home/xxxxx/.local/lib/python3.8/site-packages/cryptography/hazmat/primitives/asymmetric/dh.py", line 11, in <module>
    from cryptography.hazmat.primitives import serialization
  File "/home/xxxxx/.local/lib/python3.8/site-packages/cryptography/hazmat/primitives/serialization/__init__.py", line 15, in <module>
    from cryptography.hazmat.primitives.serialization.base import (
  File "/home/xxxxx/.local/lib/python3.8/site-packages/cryptography/hazmat/primitives/serialization/base.py", line 28, in <module>
    def load_pem_parameters(data: bytes, backend=None) -> dh.DHParameters:
AttributeError: partially initialized module 'cryptography.hazmat.primitives.asymmetric.dh' has no attribute 'DHParameters' (most likely due to a circular import)

import time
from cryptography.hazmat.primitives.asymmetric import dh


for i in [2048,3072,4096]:
    begin=time.time()
    params = dh.generate_parameters(
        generator=2,
        key_size=i,
    )
    end=time.time()
    print('took {}s for {} keysize'.format(int(end-begin), i))