c++ base64（转）

转：http://www.adp-gmbh.ch/cpp/common/base64.html

  1 /* 
  2    base64.cpp and base64.h
  3 
  4    Copyright (C) 2004-2008 René Nyffenegger
  5 
  6    This source code is provided 'as-is', without any express or implied
  7    warranty. In no event will the author be held liable for any damages
  8    arising from the use of this software.
  9 
 10    Permission is granted to anyone to use this software for any purpose,
 11    including commercial applications, and to alter it and redistribute it
 12    freely, subject to the following restrictions:
 13 
 14    1. The origin of this source code must not be misrepresented; you must not
 15       claim that you wrote the original source code. If you use this source code
 16       in a product, an acknowledgment in the product documentation would be
 17       appreciated but is not required.
 18 
 19    2. Altered source versions must be plainly marked as such, and must not be
 20       misrepresented as being the original source code.
 21 
 22    3. This notice may not be removed or altered from any source distribution.
 23 
 24    René Nyffenegger rene.nyffenegger@adp-gmbh.ch
 25 
 26 */
 27 
 28 #include "base64.h"
 29 #include <iostream>
 30 
 31 static const std::string base64_chars = 
 32              "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 33              "abcdefghijklmnopqrstuvwxyz"
 34              "0123456789+/";
 35 
 36 
 37 static inline bool is_base64(unsigned char c) {
 38   return (isalnum(c) || (c == '+') || (c == '/'));
 39 }
 40 
 41 std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {
 42   std::string ret;
 43   int i = 0;
 44   int j = 0;
 45   unsigned char char_array_3[3];
 46   unsigned char char_array_4[4];
 47 
 48   while (in_len--) {
 49     char_array_3[i++] = *(bytes_to_encode++);
 50     if (i == 3) {
 51       char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
 52       char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
 53       char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
 54       char_array_4[3] = char_array_3[2] & 0x3f;
 55 
 56       for(i = 0; (i <4) ; i++)
 57         ret += base64_chars[char_array_4[i]];
 58       i = 0;
 59     }
 60   }
 61 
 62   if (i)
 63   {
 64     for(j = i; j < 3; j++)
 65       char_array_3[j] = '\0';
 66 
 67     char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
 68     char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
 69     char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
 70     char_array_4[3] = char_array_3[2] & 0x3f;
 71 
 72     for (j = 0; (j < i + 1); j++)
 73       ret += base64_chars[char_array_4[j]];
 74 
 75     while((i++ < 3))
 76       ret += '=';
 77 
 78   }
 79 
 80   return ret;
 81 
 82 }
 83 
 84 std::string base64_decode(std::string const& encoded_string) {
 85   int in_len = encoded_string.size();
 86   int i = 0;
 87   int j = 0;
 88   int in_ = 0;
 89   unsigned char char_array_4[4], char_array_3[3];
 90   std::string ret;
 91 
 92   while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
 93     char_array_4[i++] = encoded_string[in_]; in_++;
 94     if (i ==4) {
 95       for (i = 0; i <4; i++)
 96         char_array_4[i] = base64_chars.find(char_array_4[i]);
 97 
 98       char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
 99       char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
100       char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
101 
102       for (i = 0; (i < 3); i++)
103         ret += char_array_3[i];
104       i = 0;
105     }
106   }
107 
108   if (i) {
109     for (j = i; j <4; j++)
110       char_array_4[j] = 0;
111 
112     for (j = 0; j <4; j++)
113       char_array_4[j] = base64_chars.find(char_array_4[j]);
114 
115     char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
116     char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
117     char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
118 
119     for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
120   }
121 
122   return ret;
123 }
base64.cpp
1 #include <string>
2 
3 std::string base64_encode(unsigned char const* , unsigned int len);
4 std::string base64_decode(std::string const& s);
base64.h
 1 #include "base64.h"
 2 #include <iostream>
 3 
 4 int main() {
 5   const std::string s = "ADP GmbH\nAnalyse Design & Programmierung\nGesellschaft mit beschränkter Haftung" ;
 6 
 7   std::string encoded = base64_encode(reinterpret_cast<const unsigned char*>(s.c_str()), s.length());
 8   std::string decoded = base64_decode(encoded);
 9 
10   std::cout << "encoded: " << encoded << std::endl;
11   std::cout << "decoded: " << decoded << std::endl;
12 
13   return 0;
14 }
main.cpp

 

posted @ 2016-06-24 18:11  武装三藏  阅读(524)  评论(0)    收藏  举报