Current File : //lib/python3/dist-packages/paramiko/dsskey.py
# 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 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.
"""
DSS keys.
"""
from cryptography.exceptions import InvalidSignature
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import dsa
from cryptography.hazmat.primitives.asymmetric.utils import (
decode_dss_signature,
encode_dss_signature,
)
from paramiko import util
from paramiko.common import zero_byte
from paramiko.ssh_exception import SSHException
from paramiko.message import Message
from paramiko.ber import BER, BERException
from paramiko.pkey import PKey
class DSSKey(PKey):
"""
Representation of a DSS key which can be used to sign an verify SSH2
data.
"""
def __init__(
self,
msg=None,
data=None,
filename=None,
password=None,
vals=None,
file_obj=None,
):
self.p = None
self.q = None
self.g = None
self.y = None
self.x = None
self.public_blob = 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.p, self.q, self.g, self.y = vals
else:
self._check_type_and_load_cert(
msg=msg,
key_type="ssh-dss",
cert_type="ssh-dss-cert-v01@openssh.com",
)
self.p = msg.get_mpint()
self.q = msg.get_mpint()
self.g = msg.get_mpint()
self.y = msg.get_mpint()
self.size = util.bit_length(self.p)
def asbytes(self):
m = Message()
m.add_string("ssh-dss")
m.add_mpint(self.p)
m.add_mpint(self.q)
m.add_mpint(self.g)
m.add_mpint(self.y)
return m.asbytes()
def __str__(self):
return self.asbytes()
@property
def _fields(self):
return (self.get_name(), self.p, self.q, self.g, self.y)
def get_name(self):
return "ssh-dss"
def get_bits(self):
return self.size
def can_sign(self):
return self.x is not None
def sign_ssh_data(self, data, algorithm=None):
key = dsa.DSAPrivateNumbers(
x=self.x,
public_numbers=dsa.DSAPublicNumbers(
y=self.y,
parameter_numbers=dsa.DSAParameterNumbers(
p=self.p, q=self.q, g=self.g
),
),
).private_key(backend=default_backend())
sig = key.sign(data, hashes.SHA1())
r, s = decode_dss_signature(sig)
m = Message()
m.add_string("ssh-dss")
# apparently, in rare cases, r or s may be shorter than 20 bytes!
rstr = util.deflate_long(r, 0)
sstr = util.deflate_long(s, 0)
if len(rstr) < 20:
rstr = zero_byte * (20 - len(rstr)) + rstr
if len(sstr) < 20:
sstr = zero_byte * (20 - len(sstr)) + sstr
m.add_string(rstr + sstr)
return m
def verify_ssh_sig(self, data, msg):
if len(msg.asbytes()) == 40:
# spies.com bug: signature has no header
sig = msg.asbytes()
else:
kind = msg.get_text()
if kind != "ssh-dss":
return 0
sig = msg.get_binary()
# pull out (r, s) which are NOT encoded as mpints
sigR = util.inflate_long(sig[:20], 1)
sigS = util.inflate_long(sig[20:], 1)
signature = encode_dss_signature(sigR, sigS)
key = dsa.DSAPublicNumbers(
y=self.y,
parameter_numbers=dsa.DSAParameterNumbers(
p=self.p, q=self.q, g=self.g
),
).public_key(backend=default_backend())
try:
key.verify(signature, data, hashes.SHA1())
except InvalidSignature:
return False
else:
return True
def write_private_key_file(self, filename, password=None):
key = dsa.DSAPrivateNumbers(
x=self.x,
public_numbers=dsa.DSAPublicNumbers(
y=self.y,
parameter_numbers=dsa.DSAParameterNumbers(
p=self.p, q=self.q, g=self.g
),
),
).private_key(backend=default_backend())
self._write_private_key_file(
filename,
key,
serialization.PrivateFormat.TraditionalOpenSSL,
password=password,
)
def write_private_key(self, file_obj, password=None):
key = dsa.DSAPrivateNumbers(
x=self.x,
public_numbers=dsa.DSAPublicNumbers(
y=self.y,
parameter_numbers=dsa.DSAParameterNumbers(
p=self.p, q=self.q, g=self.g
),
),
).private_key(backend=default_backend())
self._write_private_key(
file_obj,
key,
serialization.PrivateFormat.TraditionalOpenSSL,
password=password,
)
@staticmethod
def generate(bits=1024, progress_func=None):
"""
Generate a new private DSS key. This factory function can be used to
generate a new host key or authentication key.
:param int bits: number of bits the generated key should be.
:param progress_func: Unused
:return: new `.DSSKey` private key
"""
numbers = dsa.generate_private_key(
bits, backend=default_backend()
).private_numbers()
key = DSSKey(
vals=(
numbers.public_numbers.parameter_numbers.p,
numbers.public_numbers.parameter_numbers.q,
numbers.public_numbers.parameter_numbers.g,
numbers.public_numbers.y,
)
)
key.x = numbers.x
return key
# ...internals...
def _from_private_key_file(self, filename, password):
data = self._read_private_key_file("DSA", filename, password)
self._decode_key(data)
def _from_private_key(self, file_obj, password):
data = self._read_private_key("DSA", file_obj, password)
self._decode_key(data)
def _decode_key(self, data):
pkformat, data = data
# private key file contains:
# DSAPrivateKey = { version = 0, p, q, g, y, x }
if pkformat == self._PRIVATE_KEY_FORMAT_ORIGINAL:
try:
keylist = BER(data).decode()
except BERException as e:
raise SSHException("Unable to parse key file: {}".format(e))
elif pkformat == self._PRIVATE_KEY_FORMAT_OPENSSH:
keylist = self._uint32_cstruct_unpack(data, "iiiii")
keylist = [0] + list(keylist)
else:
self._got_bad_key_format_id(pkformat)
if type(keylist) is not list or len(keylist) < 6 or keylist[0] != 0:
raise SSHException(
"not a valid DSA private key file (bad ber encoding)"
)
self.p = keylist[1]
self.q = keylist[2]
self.g = keylist[3]
self.y = keylist[4]
self.x = keylist[5]
self.size = util.bit_length(self.p)
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