ed25519 key auth fails with FileError

[epuscasu]

Bug reports

Steps to reproduce:

1. Example code that produces error.

import socket
from ssh2.session import Session

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(("dest.server", 22))

session = Session()
session.handshake(sock)

pkey = r"path\to\id_ed25519"

session.userauth_publickey_fromfile("username", pkey, "")

channel = session.open_session()
channel.execute("echo test")
print(channel.read())

2. Stack trace or error messages.

Traceback (most recent call last):                                                                                                                                                                                                                                                            
 File "C:\Users\epuscasu\AppData\Local\Programs\Python\Python310\test_ssh.py", line 23, in <module>                                                                                                                                                                                            session.userauth_publickey_fromfile("username", pkey, "")                                                                                                                                                                                                                                 
 File "ssh2\session.pyx", line 222, in ssh2.session.Session.userauth_publickey_fromfile                                                                                                                                                                                                      
 File "ssh2\utils.pyx", line 162, in ssh2.utils.handle_error_codes                                                                                                                                                                                                                         ssh2.exceptions.FileError          

Expected behaviour: Successful connection, (5, b'test\n') output.

Actual behaviour: ssh2.exceptions.FileError . Using a RSA key performs as expected.

Additional info: ssh2-python version 0.27.0 , Windows 10 x64, Python 3.10.

Possible cause - the OpenSSL version bundled with the PyPI packages might be outdated on some platforms. EdDSA support was included in 1.1.1 (https://www.openssl.org/blog/blog/2018/09/11/release111/)

[pkittenis]

Hi there,

Thanks for the interest and report.

This is a known issue with publickey_fromfile and ED25519 keys on Windows only. I suspect Window's file locking behaviour is the root cause.

Use userauth_publickey_frommemory instead to work around.

[epuscasu]

Use userauth_publickey_frommemory instead to work around.

Does not work, same behavior. Any other suggestions?

[pkittenis]

Yes, also tested.

I've not found a way to make ED25519 keys work on Windows clients. I'd suggest using ECDSA or any other type of key.

Can also use the high level client pssh.clients.ssh.SSHClient - documentation here.

[pkittenis]

Reference ParallelSSH/parallel-ssh#285

ED25519 key files cannot be loaded by neither userauth_publickey_fromfile nor userauth_publickey_frommemory on Windows clients only.

Most probably a bug with upstream libssh2. Needs C test case and tracing output to investigate and raise with libssh2.

[ionutbaltariu]

Hello @pkittenis!
Any updates on this issue?

[ionutbaltariu]

Hello again, @pkittenis

It seems the issue was fixed in the latest version of libssh2. Is there a chance to update libssh2 on this repository as well?

[pkittenis]

Pending new release of libssh2 that contains the fix.

1.10.0 is so far the latest version and it does not contain the fix.