esp32-Encrypt

This little example project will focus on how to cipher or decipher data with AES-128 in ECB mode, on the Arduino core running on the ESP32. Based on the examples mentioned on techtutorialsx.com and github.com i have created the class Cipher to encrypt and decrypt a whole string with variable length. To store the result on the internal storage of the ESP32, the class CSPIFFS is quite helpfull to achieve this aim.

Here is a little arduino console output picture to visualize project achievements:

Quick start

To use my created class, you only have to include the Cipher.h file in your current Arduino sketch and create an object of it. Now you have to set a secure cipher key to encrypt your data (in this example a simple string). The encryption result can be stored in a string with calling the function encryptString(). Decrypting the encrypted data can be achieved by using the decryptString() function.

  #include "Cipher.h"

  Cipher * cipher = new Cipher();

  void setup() {
    char * key = "abcdefghijklmnop";
    cipher->setKey(key);

    String data = "ESP32 AES128bit Encryption example";
    String cipherString = cipher->encryptString(data);
    String decipheredString = cipher->decryptString(cipherString);
  }

  void loop() {

  }

Using the internal storage for saving purposes

If you want to save the encrypted string on the internal storage (e.g use case of a secure config file), you have to include the SPIFFSTest.h. Storing and loading the content form Spiffs is now very easly. You just have to call the method writeFile() to save a string in a file and the method getFile() to load the content of a file into an string which will be used to decrypt.

  #include "SPIFFSTest.h"

  ...

  CSPIFFS mSpiffs;

  void setup() {
    SPIFFS.begin(true);

    ...

    mSpiffs.writeFile(SPIFFS, "/test.txt", cipher->encryptString(data) );
    String decipheredString = cipher->decryptString(mSpiffs.getFile(SPIFFS, "/test.txt"));
  }

  void loop() {

  }