/usr/lib/python3/dist-packages/paramiko/primes.py is in python3-paramiko 1.15.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 | # 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.
"""
Utility functions for dealing with primes.
"""
import os
from paramiko import util
from paramiko.py3compat import byte_mask, long
from paramiko.ssh_exception import SSHException
from paramiko.common import *
def _roll_random(n):
"""returns a random # from 0 to N-1"""
bits = util.bit_length(n - 1)
byte_count = (bits + 7) // 8
hbyte_mask = pow(2, bits % 8) - 1
# so here's the plan:
# we fetch as many random bits as we'd need to fit N-1, and if the
# generated number is >= N, we try again. in the worst case (N-1 is a
# power of 2), we have slightly better than 50% odds of getting one that
# fits, so i can't guarantee that this loop will ever finish, but the odds
# of it looping forever should be infinitesimal.
while True:
x = os.urandom(byte_count)
if hbyte_mask > 0:
x = byte_mask(x[0], hbyte_mask) + x[1:]
num = util.inflate_long(x, 1)
if num < n:
break
return num
class ModulusPack (object):
"""
convenience object for holding the contents of the /etc/ssh/moduli file,
on systems that have such a file.
"""
def __init__(self):
# pack is a hash of: bits -> [ (generator, modulus) ... ]
self.pack = {}
self.discarded = []
def _parse_modulus(self, line):
timestamp, mod_type, tests, tries, size, generator, modulus = line.split()
mod_type = int(mod_type)
tests = int(tests)
tries = int(tries)
size = int(size)
generator = int(generator)
modulus = long(modulus, 16)
# weed out primes that aren't at least:
# type 2 (meets basic structural requirements)
# test 4 (more than just a small-prime sieve)
# tries < 100 if test & 4 (at least 100 tries of miller-rabin)
if (mod_type < 2) or (tests < 4) or ((tests & 4) and (tests < 8) and (tries < 100)):
self.discarded.append((modulus, 'does not meet basic requirements'))
return
if generator == 0:
generator = 2
# there's a bug in the ssh "moduli" file (yeah, i know: shock! dismay!
# call cnn!) where it understates the bit lengths of these primes by 1.
# this is okay.
bl = util.bit_length(modulus)
if (bl != size) and (bl != size + 1):
self.discarded.append((modulus, 'incorrectly reported bit length %d' % size))
return
if bl not in self.pack:
self.pack[bl] = []
self.pack[bl].append((generator, modulus))
def read_file(self, filename):
"""
:raises IOError: passed from any file operations that fail.
"""
self.pack = {}
with open(filename, 'r') as f:
for line in f:
line = line.strip()
if (len(line) == 0) or (line[0] == '#'):
continue
try:
self._parse_modulus(line)
except:
continue
def get_modulus(self, min, prefer, max):
bitsizes = sorted(self.pack.keys())
if len(bitsizes) == 0:
raise SSHException('no moduli available')
good = -1
# find nearest bitsize >= preferred
for b in bitsizes:
if (b >= prefer) and (b < max) and (b < good or good == -1):
good = b
# if that failed, find greatest bitsize >= min
if good == -1:
for b in bitsizes:
if (b >= min) and (b < max) and (b > good):
good = b
if good == -1:
# their entire (min, max) range has no intersection with our range.
# if their range is below ours, pick the smallest. otherwise pick
# the largest. it'll be out of their range requirement either way,
# but we'll be sending them the closest one we have.
good = bitsizes[0]
if min > good:
good = bitsizes[-1]
# now pick a random modulus of this bitsize
n = _roll_random(len(self.pack[good]))
return self.pack[good][n]
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