text: /* 
     base64.cpp and base64.h
  
     Copyright (C) 2004-2008 René Nyffenegger
  
     This source code is provided 'as-is', without any express or implied
     warranty. In no event will the author be held liable for any damages
     arising from the use of this software.
  
     Permission is granted to anyone to use this software for any purpose,
     including commercial applications, and to alter it and redistribute it
     freely, subject to the following restrictions:
  
     1. The origin of this source code must not be misrepresented; you must not
        claim that you wrote the original source code. If you use this source code
        in a product, an acknowledgment in the product documentation would be
        appreciated but is not required.
  
     2. Altered source versions must be plainly marked as such, and must not be
        misrepresented as being the original source code.
  
     3. This notice may not be removed or altered from any source distribution.
  
     René Nyffenegger rene.nyffenegger@adp-gmbh.ch
  
  */
  
  #include "base64.h"
  #include <iostream>
  
  static const std::string base64_chars = 
               "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
               "abcdefghijklmnopqrstuvwxyz"
               "0123456789+/";
  
  
  static inline bool is_base64(unsigned char c) {
    return (isalnum(c) || (c == '+') || (c == '/'));
  }
  
  std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {
    std::string ret;
    ret.reserve(in_len * 2);
    int i = 0;
    int j = 0;
    unsigned char char_array_3[3];
    unsigned char char_array_4[4];
  
    while (in_len--) {
      char_array_3[i++] = *(bytes_to_encode++);
      if (i == 3) {
        char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
        char_array_4[3] = char_array_3[2] & 0x3f;
  
        for(i = 0; (i <4) ; i++)
          ret += base64_chars[char_array_4[i]];
        i = 0;
      }
    }
  
    if (i)
    {
      for(j = i; j < 3; j++)
        char_array_3[j] = '\0';
  
      char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
      char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
      char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
      char_array_4[3] = char_array_3[2] & 0x3f;
  
      for (j = 0; (j < i + 1); j++)
        ret += base64_chars[char_array_4[j]];
  
      while((i++ < 3))
        ret += '=';
  
    }
  
    return std::move(ret);
  
  }
  
  std::string base64_decode(std::string const& encoded_string) {
    size_t in_len = encoded_string.size();
    int i = 0;
    int j = 0;
    int in_ = 0;
    unsigned char char_array_4[4], char_array_3[3];
    std::string ret;
  
    while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
      char_array_4[i++] = encoded_string[in_]; in_++;
      if (i ==4) {
        for (i = 0; i <4; i++)
          char_array_4[i] = static_cast<unsigned char>(base64_chars.find(char_array_4[i]));
  
        char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
        char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
        char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
  
        for (i = 0; (i < 3); i++)
          ret += char_array_3[i];
        i = 0;
      }
    }
  
    if (i) {
      for (j = i; j <4; j++)
        char_array_4[j] = 0;
  
      for (j = 0; j <4; j++)
        char_array_4[j] = static_cast<unsigned char>(base64_chars.find(char_array_4[j]));
  
      char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
      char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
      char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
  
      for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
    }
  
    return std::move(ret);
  }
  