Encode.cpp

#include "Encode.h"
#include <openssl/evp.h>
#include <openssl/bio.h>
#include <openssl/buffer.h>

std::string Base64Encode(uint8_t const* input, size_t length)
{
   BIO *b64 = BIO_new(BIO_f_base64());
   BIO *mem = BIO_new(BIO_s_mem());
   mem = BIO_push(b64, mem);
   //BIO_set_flags(mem, BIO_FLAGS_BASE64_NO_NL);
   
   BIO_write(mem, input, length);
   BIO_flush(mem);
   
   BUF_MEM *buffer = nullptr;
   BIO_get_mem_ptr(mem, &buffer);
   
   char *data = new char[buffer->length];
   memcpy(data, buffer->data, buffer->length - 1);
   data[buffer->length - 1] = 0;
   
   std::string output(data);
   BIO_free_all(mem);
   
   return output;
}

void Base64Decode(std::string const& input, uint8_t* output, size_t outputSize)
{
   // https://www.openssl.org/docs/manmaster/crypto/bio.html
   // https://www.openssl.org/docs/manmaster/crypto/BIO_f_base64.html
   BIO *b64 = BIO_new(BIO_f_base64());
   BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
   
   auto data = const_cast<char *>(input.c_str());
   auto size = input.size();
   BIO *memoryBuffer = BIO_new_mem_buf(data, size);
   
   // https://www.openssl.org/docs/manmaster/crypto/BIO_push.html
   // Chain is b64 - memoryBuffer. Writing to it encodes to base64, reading decodes.
   memoryBuffer = BIO_push(b64, memoryBuffer);
   int read = BIO_read(memoryBuffer, output, outputSize);
      
   BIO_free_all(memoryBuffer);
}