PracticalCrypto

A simple library to encrypt and decrypt strings with hashing, for ESP8266, based on BearSSL library that is already available on the ESP8266 Arduino core.

Based on "Practical IoT Cryptography On The Espressif ESP8266", by Sean Boyce on Hackaday, published at June 20, 2017.

Implementation details of this library are shown at https://gutierrezps.wordpress.com/2020/05/25/practical-iot-cryptography-on-the-esp8266-using-arduino/.

Features

• Simple usage, only three main methods can be used
• String inputs and outputs
• Encryption key generation

Examples

The examples folder contains library examples for Arduino. The extras folder contains examples for PHP (run with php <example>.php) and NodeJS (run with nodejs <example>.js).

API

• bool setKey(String key) - Set an encryption key (exactly 64 char long), Returns true if key was set sucessfully set.
• String getKey() - Returns the key currently set.
• String generateKey() - Generates a random 64-char long encryption key.
• String encrypt(String plaintext) - Encrypts the given plaintext with the key set previously. Returns the ciphertext encoded as an hex string.
• String decrypt(String ciphertext) - Decrypts the given ciphertext hex string with the key set previously. Returns the original plaintext.
• uint16_t hexStringToArray(String input, uint8_t *output, uint16_t capacity) - Converts an hex string to a byte array.
• String arrayToHexString(uint8_t *input, uint16_t len) - Converts a byte array to an hex string.
• PracticalCrypto::Status lastStatus() - If something went wrong while encrypting, decrypting or converting from hex to binary, lastStatus() will indicate what went wrong.