python python-3.x ssh paramiko private-key

Trying to specify key for paramiko SSHClient, error: Could not deserialize key data

I'm trying to create a Python script, to ssh to multiple servers and execute bash commands.

For this, I'm using Paramiko, and this has led to some problems.

For some reason, my OpenSSH SSH key doesn't work, but this I have solved by creating a new one, with a different format.

This has led to me having to specify which key I want to use, to start with I tried to connect without a password specified, but then Paramiko couldn't decrypt the key.

password = "somepassword"
pkey_path = "/Users/user1/.ssh/id_rsa_copy"
key = RSAKey.from_private_key_file(pkey_path,password=password)

c = SSHClient()
c.set_missing_host_key_policy(AutoAddPolicy())

c.connect('somesite.com',password=password,pkey=key,look_for_keys=False)
stdin, stdout, stderr = c.exec_command('uptime')
c.close()

When executing the script, I receive the following error:

Traceback (most recent call last):
  File "/Users/user1/projects/my_first_venv/lib/python3.7/site-packages/paramiko/rsakey.py", line 185, in _decode_key
    data, password=None, backend=default_backend()
  File "/Users/user1/projects/my_first_venv/lib/python3.7/site-packages/cryptography/hazmat/primitives/serialization/base.py", line 28, in load_der_private_key
    return backend.load_der_private_key(data, password)
  File "/Users/user1/projects/my_first_venv/lib/python3.7/site-packages/cryptography/hazmat/backends/openssl/backend.py", line 1106, in load_der_private_key
    password,
  File "/Users/user1/projects/my_first_venv/lib/python3.7/site-packages/cryptography/hazmat/backends/openssl/backend.py", line 1277, in _load_key
    self._handle_key_loading_error()
  File "/Users/user1/projects/my_first_venv/lib/python3.7/site-packages/cryptography/hazmat/backends/openssl/backend.py", line 1335, in _handle_key_loading_error
    raise ValueError("Could not deserialize key data.")
ValueError: Could not deserialize key data.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/user1/projects/python/paramiko-puppet.py", line 7, in <module>
    key = RSAKey.from_private_key_file(pkey_path,password=password)
  File "/Users/user1/projects/my_first_venv/lib/python3.7/site-packages/paramiko/pkey.py", line 206, in from_private_key_file
    key = cls(filename=filename, password=password)
  File "/Users/user1/projects/my_first_venv/lib/python3.7/site-packages/paramiko/rsakey.py", line 55, in __init__
    self._from_private_key_file(filename, password)
  File "/Users/user1/projects/my_first_venv/lib/python3.7/site-packages/paramiko/rsakey.py", line 176, in _from_private_key_file
    self._decode_key(data)
  File "/Users/user1/projects/my_first_venv/lib/python3.7/site-packages/paramiko/rsakey.py", line 188, in _decode_key
    raise SSHException(str(e))
paramiko.ssh_exception.SSHException: Could not deserialize key data.

Here is the command which I used to generate a new SSH key, and what a key looks like when generated.

First I copied my current SSH key and then "transformed" it.

ssh-keygen -p -m PEM -f ~/.ssh/id_rsa_copy

New key:

Solution

If I do exactly the same, it works for me.

But if I use a wrong passphrase in password=password, I get the same error as you get. So double check that you use the correct passphrase.

The password argument of from_private_key_file is your private key passphrase, not your account password.

In general you should not even need any account password, if you use private key, so I'm not sure why you pass password in the connect call – but that's not the immediate issue now.