mirror of
https://github.com/elseif/MikroTikPatch.git
synced 2025-01-23 13:35:09 +03:00
49 lines
1.7 KiB
Python
49 lines
1.7 KiB
Python
#
|
|
# toyecc - A small Elliptic Curve Cryptography Demonstration.
|
|
# Copyright (C) 2011-2022 Johannes Bauer
|
|
#
|
|
# This file is part of toyecc.
|
|
#
|
|
# toyecc is free software; you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License as published by
|
|
# the Free Software Foundation; this program is ONLY licensed under
|
|
# version 3 of the License, later versions are explicitly excluded.
|
|
#
|
|
# toyecc 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 General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU General Public License
|
|
# along with toyecc; if not, write to the Free Software
|
|
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
#
|
|
# Johannes Bauer <JohannesBauer@gmx.de>
|
|
#
|
|
|
|
def secure_rand(length):
|
|
import os
|
|
"""Returns a secure random bytes() object of the length 'length' bytes."""
|
|
data = os.urandom(length)
|
|
assert(len(data) == length)
|
|
return data
|
|
|
|
|
|
def secure_rand_int(max_value):
|
|
"""Yields a value 0 <= return < maxvalue."""
|
|
assert(max_value >= 2)
|
|
bytecnt = ((max_value - 1).bit_length() + 7) // 8
|
|
max_bin_value = 256 ** bytecnt
|
|
wholecnt = max_bin_value // max_value
|
|
cutoff = wholecnt * max_value
|
|
while True:
|
|
rnd = sum((value << (8 * bytepos)) for (bytepos, value) in enumerate(secure_rand(bytecnt)))
|
|
if rnd < cutoff:
|
|
break
|
|
return rnd % max_value
|
|
|
|
def secure_rand_int_between(min_value, max_value):
|
|
"""Yields a random number which goes from min_value (inclusive) to
|
|
max_value (inclusive)."""
|
|
return secure_rand_int(max_value - min_value + 1) + min_value
|