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# Copyright (C) 2003-2007 Robey Pointer <robeypointer@gmail.com>
#
# 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 distrubuted 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.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
"""
ECDSA keys
"""
import binascii
from hashlib import sha256
from ecdsa import SigningKey, VerifyingKey, der, curves
from paramiko.common import four_byte, one_byte
from paramiko.message import Message
from paramiko.pkey import PKey
from paramiko.py3compat import byte_chr, u
from paramiko.ssh_exception import SSHException
class ECDSAKey (PKey):
"""
Representation of an ECDSA key which can be used to sign and verify SSH2
data.
"""
def __init__(self, msg=None, data=None, filename=None, password=None,
vals=None, file_obj=None, validate_point=True):
self.verifying_key = None
self.signing_key = None
if file_obj is not None:
self._from_private_key(file_obj, password)
return
if filename is not None:
self._from_private_key_file(filename, password)
return
if (msg is None) and (data is not None):
msg = Message(data)
if vals is not None:
self.signing_key, self.verifying_key = vals
else:
if msg is None:
raise SSHException('Key object may not be empty')
if msg.get_text() != 'ecdsa-sha2-nistp256':
raise SSHException('Invalid key')
curvename = msg.get_text()
if curvename != 'nistp256':
raise SSHException("Can't handle curve of type %s" % curvename)
pointinfo = msg.get_binary()
if pointinfo[0:1] != four_byte:
raise SSHException('Point compression is being used: %s' %
binascii.hexlify(pointinfo))
self.verifying_key = VerifyingKey.from_string(pointinfo[1:],
curve=curves.NIST256p,
validate_point=validate_point)
self.size = 256
def asbytes(self):
key = self.verifying_key
m = Message()
m.add_string('ecdsa-sha2-nistp256')
m.add_string('nistp256')
point_str = four_byte + key.to_string()
m.add_string(point_str)
return m.asbytes()
def __str__(self):
return self.asbytes()
def __hash__(self):
h = hash(self.get_name())
h = h * 37 + hash(self.verifying_key.pubkey.point.x())
h = h * 37 + hash(self.verifying_key.pubkey.point.y())
return hash(h)
def get_name(self):
return 'ecdsa-sha2-nistp256'
def get_bits(self):
return self.size
def can_sign(self):
return self.signing_key is not None
def sign_ssh_data(self, data):
sig = self.signing_key.sign_deterministic(
data, sigencode=self._sigencode, hashfunc=sha256)
m = Message()
m.add_string('ecdsa-sha2-nistp256')
m.add_string(sig)
return m
def verify_ssh_sig(self, data, msg):
if msg.get_text() != 'ecdsa-sha2-nistp256':
return False
sig = msg.get_binary()
# verify the signature by SHA'ing the data and encrypting it
# using the public key.
hash_obj = sha256(data).digest()
return self.verifying_key.verify_digest(sig, hash_obj,
sigdecode=self._sigdecode)
def write_private_key_file(self, filename, password=None):
key = self.signing_key or self.verifying_key
self._write_private_key_file('EC', filename, key.to_der(), password)
def write_private_key(self, file_obj, password=None):
key = self.signing_key or self.verifying_key
self._write_private_key('EC', file_obj, key.to_der(), password)
@staticmethod
def generate(curve=curves.NIST256p, progress_func=None):
"""
Generate a new private ECDSA key. This factory function can be used to
generate a new host key or authentication key.
:param function progress_func: Not used for this type of key.
:returns: A new private key (`.ECDSAKey`) object
"""
signing_key = SigningKey.generate(curve)
key = ECDSAKey(vals=(signing_key, signing_key.get_verifying_key()))
return key
### internals...
def _from_private_key_file(self, filename, password):
data = self._read_private_key_file('EC', filename, password)
self._decode_key(data)
def _from_private_key(self, file_obj, password):
data = self._read_private_key('EC', file_obj, password)
self._decode_key(data)
ALLOWED_PADDINGS = [one_byte, byte_chr(2) * 2, byte_chr(3) * 3, byte_chr(4) * 4,
byte_chr(5) * 5, byte_chr(6) * 6, byte_chr(7) * 7]
def _decode_key(self, data):
s, padding = der.remove_sequence(data)
if padding:
if padding not in self.ALLOWED_PADDINGS:
raise ValueError("weird padding: %s" % u(binascii.hexlify(data)))
data = data[:-len(padding)]
key = SigningKey.from_der(data)
self.signing_key = key
self.verifying_key = key.get_verifying_key()
self.size = 256
def _sigencode(self, r, s, order):
msg = Message()
msg.add_mpint(r)
msg.add_mpint(s)
return msg.asbytes()
def _sigdecode(self, sig, order):
msg = Message(sig)
r = msg.get_mpint()
s = msg.get_mpint()
return r, s
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