EncoderBase64.cpp

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/*
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    Copyright (C) 2004, 2005, 2007 EPFL, Politecnico di Milano, INRIA
    Copyright (C) 2010 EPFL, Politecnico di Milano, Emory University

    This file is part of LifeV.

    LifeV is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
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/*!
  @file
  @brief An algorithm to encode / decode a string into base64 format

  The code was written by RenŽ Nyffenegger (original Copyright notice follows)

  @date 3-9-2011

  @maintainer Tiziano Passerini <tiziano@mathcs.emory.edu>
 */

/*
   base64.cpp and base64.h

   Copyright (C) 2004-2008 RenŽ 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.

   RenŽ Nyffenegger rene.nyffenegger@adp-gmbh.ch

 */

#include <lifev/core/util/EncoderBase64.hpp>
#include <iostream>

namespace LifeV
{

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, UInt in_len)
{
    std::string ret;
    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 ret;

}

std::string base64_decode (std::string const& encoded_string)
{
    int 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] = 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] = 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 ret;
}

}