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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 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.
"""
RSA keys.
"""
from cryptography.exceptions import InvalidSignature, UnsupportedAlgorithm
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import rsa, padding
from paramiko.message import Message
from paramiko.pkey import PKey
from paramiko.ssh_exception import SSHException
class RSAKey(PKey):
"""
Representation of an RSA key which can be used to sign and verify SSH2
data.
"""
HASHES = {
"ssh-rsa": hashes.SHA1,
"ssh-rsa-cert-v01@openssh.com": hashes.SHA1,
"rsa-sha2-256": hashes.SHA256,
"rsa-sha2-256-cert-v01@openssh.com": hashes.SHA256,
"rsa-sha2-512": hashes.SHA512,
"rsa-sha2-512-cert-v01@openssh.com": hashes.SHA512,
}
def __init__(
self,
msg=None,
data=None,
filename=None,
password=None,
key=None,
file_obj=None,
):
self.key = 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 key is not None:
self.key = key
else:
self._check_type_and_load_cert(
msg=msg,
# NOTE: this does NOT change when using rsa2 signatures; it's
# purely about key loading, not exchange or verification
key_type="ssh-rsa",
cert_type="ssh-rsa-cert-v01@openssh.com",
)
self.key = rsa.RSAPublicNumbers(
e=msg.get_mpint(), n=msg.get_mpint()
).public_key(default_backend())
@property
def size(self):
return self.key.key_size
@property
def public_numbers(self):
if isinstance(self.key, rsa.RSAPrivateKey):
return self.key.private_numbers().public_numbers
else:
return self.key.public_numbers()
def asbytes(self):
m = Message()
m.add_string("ssh-rsa")
m.add_mpint(self.public_numbers.e)
m.add_mpint(self.public_numbers.n)
return m.asbytes()
def __str__(self):
# NOTE: see #853 to explain some legacy behavior.
# TODO 4.0: replace with a nice clean fingerprint display or something
return self.asbytes().decode("utf8", errors="ignore")
@property
def _fields(self):
return (self.get_name(), self.public_numbers.e, self.public_numbers.n)
def get_name(self):
return "ssh-rsa"
def get_bits(self):
return self.size
def can_sign(self):
return isinstance(self.key, rsa.RSAPrivateKey)
def sign_ssh_data(self, data, algorithm="ssh-rsa"):
sig = self.key.sign(
data,
padding=padding.PKCS1v15(),
algorithm=self.HASHES[algorithm](),
)
m = Message()
m.add_string(algorithm.replace("-cert-v01@openssh.com", ""))
m.add_string(sig)
return m
def verify_ssh_sig(self, data, msg):
sig_algorithm = msg.get_text()
if sig_algorithm not in self.HASHES:
return False
key = self.key
if isinstance(key, rsa.RSAPrivateKey):
key = key.public_key()
# NOTE: pad received signature with leading zeros, key.verify()
# expects a signature of key size (e.g. PuTTY doesn't pad)
sign = msg.get_binary()
diff = key.key_size - len(sign) * 8
if diff > 0:
sign = b"\x00" * ((diff + 7) // 8) + sign
try:
key.verify(
sign, data, padding.PKCS1v15(), self.HASHES[sig_algorithm]()
)
except InvalidSignature:
return False
else:
return True
def write_private_key_file(self, filename, password=None):
self._write_private_key_file(
filename,
self.key,
serialization.PrivateFormat.TraditionalOpenSSL,
password=password,
)
def write_private_key(self, file_obj, password=None):
self._write_private_key(
file_obj,
self.key,
serialization.PrivateFormat.TraditionalOpenSSL,
password=password,
)
@staticmethod
def generate(bits, progress_func=None):
"""
Generate a new private RSA 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 `.RSAKey` private key
"""
key = rsa.generate_private_key(
public_exponent=65537, key_size=bits, backend=default_backend()
)
return RSAKey(key=key)
# ...internals...
def _from_private_key_file(self, filename, password):
data = self._read_private_key_file("RSA", filename, password)
self._decode_key(data)
def _from_private_key(self, file_obj, password):
data = self._read_private_key("RSA", file_obj, password)
self._decode_key(data)
def _decode_key(self, data):
pkformat, data = data
if pkformat == self._PRIVATE_KEY_FORMAT_ORIGINAL:
try:
key = serialization.load_der_private_key(
data, password=None, backend=default_backend()
)
except (ValueError, TypeError, UnsupportedAlgorithm) as e:
raise SSHException(str(e))
elif pkformat == self._PRIVATE_KEY_FORMAT_OPENSSH:
n, e, d, iqmp, p, q = self._uint32_cstruct_unpack(data, "iiiiii")
public_numbers = rsa.RSAPublicNumbers(e=e, n=n)
key = rsa.RSAPrivateNumbers(
p=p,
q=q,
d=d,
dmp1=d % (p - 1),
dmq1=d % (q - 1),
iqmp=iqmp,
public_numbers=public_numbers,
).private_key(default_backend())
else:
self._got_bad_key_format_id(pkformat)
assert isinstance(key, rsa.RSAPrivateKey)
self.key = key
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