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# This file is part of paramiko.
#
# Paramiko is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# Paramiko is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
import bcrypt
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.ciphers import Cipher
import nacl.signing
from paramiko.message import Message
from paramiko.pkey import PKey, OPENSSH_AUTH_MAGIC, _unpad_openssh
from paramiko.util import b
from paramiko.ssh_exception import SSHException, PasswordRequiredException
class Ed25519Key(PKey):
"""
Representation of an `Ed25519 <https://ed25519.cr.yp.to/>`_ key.
.. note::
Ed25519 key support was added to OpenSSH in version 6.5.
.. versionadded:: 2.2
.. versionchanged:: 2.3
Added a ``file_obj`` parameter to match other key classes.
"""
def __init__(
self, msg=None, data=None, filename=None, password=None, file_obj=None
):
self.public_blob = None
verifying_key = signing_key = None
if msg is None and data is not None:
msg = Message(data)
if msg is not None:
self._check_type_and_load_cert(
msg=msg,
key_type="ssh-ed25519",
cert_type="ssh-ed25519-cert-v01@openssh.com",
)
verifying_key = nacl.signing.VerifyKey(msg.get_binary())
elif filename is not None:
with open(filename, "r") as f:
pkformat, data = self._read_private_key("OPENSSH", f)
elif file_obj is not None:
pkformat, data = self._read_private_key("OPENSSH", file_obj)
if filename or file_obj:
signing_key = self._parse_signing_key_data(data, password)
if signing_key is None and verifying_key is None:
raise ValueError("need a key")
self._signing_key = signing_key
self._verifying_key = verifying_key
def _parse_signing_key_data(self, data, password):
from paramiko.transport import Transport
# We may eventually want this to be usable for other key types, as
# OpenSSH moves to it, but for now this is just for Ed25519 keys.
# This format is described here:
# https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.key
# The description isn't totally complete, and I had to refer to the
# source for a full implementation.
message = Message(data)
if message.get_bytes(len(OPENSSH_AUTH_MAGIC)) != OPENSSH_AUTH_MAGIC:
raise SSHException("Invalid key")
ciphername = message.get_text()
kdfname = message.get_text()
kdfoptions = message.get_binary()
num_keys = message.get_int()
if kdfname == "none":
# kdfname of "none" must have an empty kdfoptions, the ciphername
# must be "none"
if kdfoptions or ciphername != "none":
raise SSHException("Invalid key")
elif kdfname == "bcrypt":
if not password:
raise PasswordRequiredException(
"Private key file is encrypted"
)
kdf = Message(kdfoptions)
bcrypt_salt = kdf.get_binary()
bcrypt_rounds = kdf.get_int()
else:
raise SSHException("Invalid key")
if ciphername != "none" and ciphername not in Transport._cipher_info:
raise SSHException("Invalid key")
public_keys = []
for _ in range(num_keys):
pubkey = Message(message.get_binary())
if pubkey.get_text() != "ssh-ed25519":
raise SSHException("Invalid key")
public_keys.append(pubkey.get_binary())
private_ciphertext = message.get_binary()
if ciphername == "none":
private_data = private_ciphertext
else:
cipher = Transport._cipher_info[ciphername]
key = bcrypt.kdf(
password=b(password),
salt=bcrypt_salt,
desired_key_bytes=cipher["key-size"] + cipher["block-size"],
rounds=bcrypt_rounds,
# We can't control how many rounds are on disk, so no sense
# warning about it.
ignore_few_rounds=True,
)
decryptor = Cipher(
cipher["class"](key[: cipher["key-size"]]),
cipher["mode"](key[cipher["key-size"] :]),
backend=default_backend(),
).decryptor()
private_data = (
decryptor.update(private_ciphertext) + decryptor.finalize()
)
message = Message(_unpad_openssh(private_data))
if message.get_int() != message.get_int():
raise SSHException("Invalid key")
signing_keys = []
for i in range(num_keys):
if message.get_text() != "ssh-ed25519":
raise SSHException("Invalid key")
# A copy of the public key, again, ignore.
public = message.get_binary()
key_data = message.get_binary()
# The second half of the key data is yet another copy of the public
# key...
signing_key = nacl.signing.SigningKey(key_data[:32])
# Verify that all the public keys are the same...
assert (
signing_key.verify_key.encode()
== public
== public_keys[i]
== key_data[32:]
)
signing_keys.append(signing_key)
# Comment, ignore.
message.get_binary()
if len(signing_keys) != 1:
raise SSHException("Invalid key")
return signing_keys[0]
def asbytes(self):
if self.can_sign():
v = self._signing_key.verify_key
else:
v = self._verifying_key
m = Message()
m.add_string("ssh-ed25519")
m.add_string(v.encode())
return m.asbytes()
@property
def _fields(self):
if self.can_sign():
v = self._signing_key.verify_key
else:
v = self._verifying_key
return (self.get_name(), v)
def get_name(self):
return "ssh-ed25519"
def get_bits(self):
return 256
def can_sign(self):
return self._signing_key is not None
def sign_ssh_data(self, data, algorithm=None):
m = Message()
m.add_string("ssh-ed25519")
m.add_string(self._signing_key.sign(data).signature)
return m
def verify_ssh_sig(self, data, msg):
if msg.get_text() != "ssh-ed25519":
return False
try:
self._verifying_key.verify(data, msg.get_binary())
except nacl.exceptions.BadSignatureError:
return False
else:
return True
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