forked from s434650/CatOrNot
58 lines
1.6 KiB
Python
58 lines
1.6 KiB
Python
|
# -*- coding: utf-8 -*-
|
||
|
|
#
|
||
|
|
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
|
||
|
|
#
|
||
|
|
# Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
# you may not use this file except in compliance with the License.
|
||
|
|
# You may obtain a copy of the License at
|
||
|
|
#
|
||
|
|
# https://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
#
|
||
|
|
# Unless required by applicable law or agreed to in writing, software
|
||
|
|
# distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
# See the License for the specific language governing permissions and
|
||
|
|
# limitations under the License.
|
||
|
|
|
||
|
|
"""Core mathematical operations.
|
||
|
|
|
||
|
|
This is the actual core RSA implementation, which is only defined
|
||
|
|
mathematically on integers.
|
||
|
|
"""
|
||
|
|
|
||
|
|
from rsa._compat import is_integer
|
||
|
|
|
||
|
|
|
||
|
|
def assert_int(var, name):
|
||
|
|
if is_integer(var):
|
||
|
|
return
|
||
|
|
|
||
|
|
raise TypeError('%s should be an integer, not %s' % (name, var.__class__))
|
||
|
|
|
||
|
|
|
||
|
|
def encrypt_int(message, ekey, n):
|
||
|
|
"""Encrypts a message using encryption key 'ekey', working modulo n"""
|
||
|
|
|
||
|
|
assert_int(message, 'message')
|
||
|
|
assert_int(ekey, 'ekey')
|
||
|
|
assert_int(n, 'n')
|
||
|
|
|
||
|
|
if message < 0:
|
||
|
|
raise ValueError('Only non-negative numbers are supported')
|
||
|
|
|
||
|
|
if message > n:
|
||
|
|
raise OverflowError("The message %i is too long for n=%i" % (message, n))
|
||
|
|
|
||
|
|
return pow(message, ekey, n)
|
||
|
|
|
||
|
|
|
||
|
|
def decrypt_int(cyphertext, dkey, n):
|
||
|
|
"""Decrypts a cypher text using the decryption key 'dkey', working modulo n"""
|
||
|
|
|
||
|
|
assert_int(cyphertext, 'cyphertext')
|
||
|
|
assert_int(dkey, 'dkey')
|
||
|
|
assert_int(n, 'n')
|
||
|
|
|
||
|
|
message = pow(cyphertext, dkey, n)
|
||
|
|
return message
|