Cape 2.0

Cape is a string encryption library developed to offer efficient encryption on small microcontrollers. Cape implements a new, private key, XOR based, stream chipher algorithm on top of which is applied a pseudo-random initialization vector encryption method. Cape is implemented in c++ and engineered to avoid any external dependency.

How to use Cape

Instantiate Cape passing the encryption key and its length.

  Cape cape("YOUR-ENCRYPTION-KEY", 19);

To encrypt a string:

  char source[] ="CRYPTMEPLEASE";
  char destination[14];
  cape.hash(source, destination, 13);                    // Light stream cypher   
  cape.encrypt(source, destination, 13, random(0, 255)); // Strong encryption

In destination it is saved the encrypted version of the string, with an additional byte at the end, used to encrypt data, called initialization vector (be sure to define your destination buffer always 1 byte longer):

  for(uint8_t i = 0; i < 14; i++)
    Serial.print(destination[i]);

If you want to come back from encrypted data to the original string:

    cape.decrypt(destination, source, 14);

Print the original string as before to check that all is working and to get back CRYPTMEPLEASE:

  for(uint8_t i = 0; i < 13; i++)
    Serial.print(source[i]);

If you need to change the encryption key after instantiation call set_key passing the new key and its length:

  cape.set_key("YOUR-ENCRYPTION-KEY", 19);

License

/*  _____  _____   _____   _____
   |      |_____| |_____| |_____
   |_____ |     | |       |_____  version 2.0

Cape Copyright (c) 2012-2017, Giovanni Blu Mitolo All rights reserved.

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. */