lib/crypto/xor_ciphers.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #     http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14
  15 # XOR oriented cryptographic ciphers and utilities.
  16 module xor_ciphers
  17
  18 redef class Bytes
  19         # Returns `self` xored with `key`
  20         #
  21         # The key is cycled through until the `self` has been completely xored.
  22         #
  23         #     assert "goodmorning".to_bytes.xorcipher(" ".to_bytes) == "GOODMORNING".bytes
  24         fun xorcipher(key: Bytes): Bytes do
  25                 var xored = new Bytes.with_capacity(self.length)
  26
  27                 for i in self.length.times do
  28                         xored.add(self[i] ^ key[i % key.length])
  29                 end
  30
  31                 return xored
  32         end
  33 end