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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.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
"""
RSA keys.
"""
import os
from hashlib import sha1
from Crypto.PublicKey import RSA
from paramiko import util
from paramiko.common import max_byte, zero_byte, one_byte
from paramiko.message import Message
from paramiko.ber import BER, BERException
from paramiko.pkey import PKey
from paramiko.py3compat import long
from paramiko.ssh_exception import SSHException
SHA1_DIGESTINFO = b'\x30\x21\x30\x09\x06\x05\x2b\x0e\x03\x02\x1a\x05\x00\x04\x14'
class RSAKey (PKey):
"""
Representation of an RSA 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):
self.n = None
self.e = None
self.d = None
self.p = None
self.q = 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.e, self.n = vals
else:
if msg is None:
raise SSHException('Key object may not be empty')
if msg.get_text() != 'ssh-rsa':
raise SSHException('Invalid key')
self.e = msg.get_mpint()
self.n = msg.get_mpint()
self.size = util.bit_length(self.n)
def asbytes(self):
m = Message()
m.add_string('ssh-rsa')
m.add_mpint(self.e)
m.add_mpint(self.n)
return m.asbytes()
def __str__(self):
return self.asbytes()
def __hash__(self):
h = hash(self.get_name())
h = h * 37 + hash(self.e)
h = h * 37 + hash(self.n)
return hash(h)
def get_name(self):
return 'ssh-rsa'
def get_bits(self):
return self.size
def can_sign(self):
return self.d is not None
def sign_ssh_data(self, data):
digest = sha1(data).digest()
rsa = RSA.construct((long(self.n), long(self.e), long(self.d)))
sig = util.deflate_long(rsa.sign(self._pkcs1imify(digest), bytes())[0], 0)
m = Message()
m.add_string('ssh-rsa')
m.add_string(sig)
return m
def verify_ssh_sig(self, data, msg):
if msg.get_text() != 'ssh-rsa':
return False
sig = util.inflate_long(msg.get_binary(), True)
# verify the signature by SHA'ing the data and encrypting it using the
# public key. some wackiness ensues where we "pkcs1imify" the 20-byte
# hash into a string as long as the RSA key.
hash_obj = util.inflate_long(self._pkcs1imify(sha1(data).digest()), True)
rsa = RSA.construct((long(self.n), long(self.e)))
return rsa.verify(hash_obj, (sig,))
def _encode_key(self):
if (self.p is None) or (self.q is None):
raise SSHException('Not enough key info to write private key file')
keylist = [0, self.n, self.e, self.d, self.p, self.q,
self.d % (self.p - 1), self.d % (self.q - 1),
util.mod_inverse(self.q, self.p)]
try:
b = BER()
b.encode(keylist)
except BERException:
raise SSHException('Unable to create ber encoding of key')
return b.asbytes()
def write_private_key_file(self, filename, password=None):
self._write_private_key_file('RSA', filename, self._encode_key(), password)
def write_private_key(self, file_obj, password=None):
self._write_private_key('RSA', file_obj, self._encode_key(), password)
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 function progress_func:
an optional function to call at key points in key generation (used
by ``pyCrypto.PublicKey``).
:return: new `.RSAKey` private key
"""
rsa = RSA.generate(bits, os.urandom, progress_func)
key = RSAKey(vals=(rsa.e, rsa.n))
key.d = rsa.d
key.p = rsa.p
key.q = rsa.q
return key
generate = staticmethod(generate)
### internals...
def _pkcs1imify(self, data):
"""
turn a 20-byte SHA1 hash into a blob of data as large as the key's N,
using PKCS1's \"emsa-pkcs1-v1_5\" encoding. totally bizarre.
"""
size = len(util.deflate_long(self.n, 0))
filler = max_byte * (size - len(SHA1_DIGESTINFO) - len(data) - 3)
return zero_byte + one_byte + filler + zero_byte + SHA1_DIGESTINFO + data
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):
# private key file contains:
# RSAPrivateKey = { version = 0, n, e, d, p, q, d mod p-1, d mod q-1, q**-1 mod p }
try:
keylist = BER(data).decode()
except BERException:
raise SSHException('Unable to parse key file')
if (type(keylist) is not list) or (len(keylist) < 4) or (keylist[0] != 0):
raise SSHException('Not a valid RSA private key file (bad ber encoding)')
self.n = keylist[1]
self.e = keylist[2]
self.d = keylist[3]
# not really needed
self.p = keylist[4]
self.q = keylist[5]
self.size = util.bit_length(self.n)
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