python paramiko CryptographyDeprecationWarning

import paramiko
client = paramiko.SSHClient()
client.connect(serverIp, port=serverPort, username=serverUser)

报警告如下：

paramiko\ecdsakey.py:164: CryptographyDeprecationWarning: Support for unsafe construction of public numbers from encoded data will be removed in a future version. Please use EllipticCurvePublicKey.from_encoded_point
  self.ecdsa_curve.curve_class(), pointinfo
paramiko\kex_ecdh_nist.py:39: CryptographyDeprecationWarning: encode_point has been deprecated on EllipticCurvePublicNumbers and will be removed in a future version. Please use EllipticCurvePublicKey.public_bytes to obtain both compressed and uncompressed point encoding.
  m.add_string(self.Q_C.public_numbers().encode_point())
paramiko\kex_ecdh_nist.py:96: CryptographyDeprecationWarning: Support for unsafe construction of public numbers from encoded data will be removed in a future version. Please use EllipticCurvePublicKey.from_encoded_point
  self.curve, Q_S_bytes
paramiko\kex_ecdh_nist.py:111: CryptographyDeprecationWarning: encode_point has been deprecated on EllipticCurvePublicNumbers and will be removed in a future version. Please use EllipticCurvePublicKey.public_bytes to obtain both compressed and uncompressed point encoding.
  hm.add_string(self.Q_C.public_numbers().encode_point())

原因

paramiko 2.4.2 依赖 cryptography，而最新的cryptography==2.5里有一些弃用的API。

解决

删掉cryptography 2.5，安装2.4.2，就不会报错了。

pip uninstall cryptography==2.5
pip install cryptography==2.4.2

补充

paramiko的issue #1369提到了这个问题，并已有PR #1379了，尚未合并。