model_coder/base64/base64.cpp

#include "base64.h"
#include <iostream>

static const std::string base64_chars =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                "abcdefghijklmnopqrstuvwxyz"
                "0123456789+/";


static inline bool is_base64(BYTE c) {
    return (isalnum(c) || (c == '+') || (c == '/'));
}

std::string base64encode(BYTE const* buf, unsigned int bufLen) {
    std::string ret;
    int i = 0, j = 0;
    BYTE char_array_3[3], char_array_4[4];

    while(bufLen--) {
        char_array_3[i++] = *(buf++);
        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::vector<BYTE> base64decode(std::string const& encoded_string) {
    int in_len = encoded_string.size(),
        i = 0,
        j = 0,
        in_ = 0;
    BYTE char_array_4[4], char_array_3[3];
    std::vector<BYTE> 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.push_back(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.push_back(char_array_3[j]);
    }

    return ret;
}