encode_decode.cpp

#include <Arduino.h>
extern "C" {
  #include "crypto/base64.h"
}

void setup() {
  Serial.begin(9600);

  const char* message = "Hello World";

  size_t outputLen;
  unsigned char *encode = base64_encode((const unsigned char*)message, strlen(message), &outputLen);
  unsigned char *decode = base64_decode(encode, outputLen, &outputLen);

  Serial.print("plaintext : "); Serial.println(message);
  Serial.print("encode    : "); Serial.println((char*)encode);
  Serial.print("decode    : "); Serial.println((char*)decode);
}

void loop() {
  
}