54 lines
1.6 KiB
Python
54 lines
1.6 KiB
Python
|
# 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.
|
||
|
"""
|
||
|
|
||
|
|
||
|
def assert_int(var: int, name: str) -> None:
|
||
|
if isinstance(var, int):
|
||
|
return
|
||
|
|
||
|
raise TypeError("%s should be an integer, not %s" % (name, var.__class__))
|
||
|
|
||
|
|
||
|
def encrypt_int(message: int, ekey: int, n: int) -> int:
|
||
|
"""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: int, dkey: int, n: int) -> int:
|
||
|
"""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
|