Base64 编码解码

Base64.hpp

#ifndef _BASE64_H
#define _BASE64_H
#include <string>

namespace PWRD{
    namespace Marshal{
        class Base64{
            public:
                static std::string encode(unsigned char const* , unsigned int len);
                static std::string decode(std::string const& s);
            private:
                static std::string base64_chars;
                static bool is_base64(unsigned char c);
        };
    };

};
#endif

 

Base64.cpp

#include "Base64.hpp"
#include <iostream>

namespace PWRD{
    namespace Marshal{
        std::string Base64::base64_chars =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            "abcdefghijklmnopqrstuvwxyz"
            "0123456789+/";


        bool Base64::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;
            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;
        }
    };
};