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# -*- 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
#
# http://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
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