//source://https://everythingesp.com/esp32-arduino-tutorial-encryption-aes128-in-ecb-mode/
//check:
  //https://the-x.cn/en-US/cryptography/Aes.aspx
  //http://aes.online-domain-tools.com/

//ascii to hex//https://onlinetools.com/hex/convert-ascii-to-hex
//#include "Seeed_mbedtls.h"
#include "mbedtls/aes.h"

void encrypt(char * plainText, char * key, unsigned char * outputBuffer){

  mbedtls_aes_context aes;

  mbedtls_aes_init( &aes );
  mbedtls_aes_setkey_enc( &aes, (const unsigned char*) key, strlen(key) * 8 );
  mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_ENCRYPT, (const unsigned char*)plainText, outputBuffer);
  mbedtls_aes_free( &aes );
}

void decrypt(unsigned char * chipherText, char * key, unsigned char * outputBuffer){

  mbedtls_aes_context aes;

  mbedtls_aes_init( &aes );
  mbedtls_aes_setkey_dec( &aes, (const unsigned char*) key, strlen(key) * 8 );
  mbedtls_aes_crypt_ecb(&aes, MBEDTLS_AES_DECRYPT, (const unsigned char*)chipherText, outputBuffer);
  mbedtls_aes_free( &aes );
}

void setup() {

  Serial.begin(115200);

  char * key = "abcdefghijklmnop";
  //unsigned char* key [] ={0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70};

  char *plainText = "Tech tutorials x";
  unsigned char cipherTextOutput[16];
  unsigned char decipheredTextOutput[16];

  encrypt(plainText, key, cipherTextOutput);
  decrypt(cipherTextOutput, key, decipheredTextOutput);

  Serial.println("\nOriginal plain text:");
  Serial.println(plainText);

  Serial.println("\nCiphered text:");
  for (int i = 0; i < 16; i++) {
    Serial.print((char)cipherTextOutput[i]);
  }
 /* for (int i = 0; i < 16; i++) {

    char str[3];

    sprintf(str, "%02x", (int)cipherTextOutput[i]);
    Serial.print(str);
  }*/

  Serial.println("\n\nDeciphered text:");
  //Serial.print(decipheredTextOutput);
  for (int i = 0; i < 16; i++) {
    Serial.print((char)decipheredTextOutput[i]);
  }
}

void loop() {}