Base64 Encoder / Decoder 【C++版】-转帖

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这个版本是纯C++版。

就两个函数，一个是base64::encode()和base64::decode(),一个用来加密一个用来解密。

下面是具体的实现。

/* base64.hpp - base64 encoder/decoder implementing section 6.8 of RFC2045 Copyright (C) 2002 Ryan Petrie (ryanpetrie@netscape.net) and released under the zlib license: This software is provided 'as-is', without any express or implied warranty. In no event will the authors 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 software must not be misrepresented; you must not claim that you wrote the original software. If you use this software 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 software. 3. This notice may not be removed or altered from any source distribution. -------------------------------------------------------------------------- base64::encoder and base64::decoder are intended to be identical in usage as the STL's std::copy and similar algorithms. They require as parameters an input iterator range and an output iterator, and just as std::copy, the iterators can be bare pointers, container iterators, or even adaptors such as ostream_iterator. Examples: // encode/decode with in-place memory buffers char source[size], dest[size*2]; base64::encode(source, source+size, dest); base64::decode(dest, dest+size*2, source); // encode from memory to a file char source[size]; ofstream file("output.txt"); base64::encode((char*)source, source+size, ostream_iterator<char>(file)); // decode from file to a standard container ifstream file("input.txt"); vector<char> dest; base64::decode(istream_iterator<char>(file), istream_iterator<char>(), back_inserter(dest) ); */ #ifndef _BASE64_HPP #define _BASE64_HPP #include <algorithm> namespace base64 { typedef unsigned uint32; typedef unsigned char uint8; extern const char* to_table; extern const char* to_table_end; extern const char* from_table; template <class InputIterator, class OutputIterator> void encode(const InputIterator& begin, const InputIterator& end, OutputIterator out) { InputIterator it = begin; int lineSize = 0; int bytes; do { uint32 input = 0; // get the next three bytes into "in" (and count how many we actually get) bytes = 0; for(; (bytes < 3) && (it != end); ++bytes, ++it) { input <<= 8; input += static_cast<uint8>(*it); } // convert to base64 int bits = bytes*8; while (bits > 0) { bits -= 6; const uint8 index = ((bits < 0) ? input << -bits : input >> bits) & 0x3F; *out = to_table[index]; ++out; ++lineSize; } if (lineSize >= 76) // ensure proper line length { *out = 13; ++out; *out = 10; ++out; lineSize = 0; } } while (bytes == 3); // add pad characters if necessary if (bytes > 0) for(int i=bytes; i < 3; ++i) { *out = '='; ++out; } } template <class InputIterator, class OutputIterator> void decode(const InputIterator& begin, const InputIterator& end, OutputIterator out) { InputIterator it = begin; int chars; do { uint8 input[4] = {0, 0, 0, 0}; // get four characters chars=0; while((chars<4) && (it != end)) { uint8 c = static_cast<char>(*it); if (c == '=') break; // pad character marks the end of the stream ++it; if (std::find(to_table, to_table_end, c) != to_table_end) { input[chars] = from_table[c]; chars++; } } // output the binary data if (chars >= 2) { *out = static_cast<uint8>((input[0] << 2) + (input[1] >> 4)); ++out; if (chars >= 3) { *out = static_cast<uint8>((input[1] << 4) + (input[2] >> 2)); ++out; if (chars >= 4) { *out = static_cast<uint8>((input[2] << 6) + input[3]); ++out; } } } } while (chars == 4); } } // end namespace #endif  

namespace base64 { const char _to_table[64] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' }; const char* to_table = _to_table; const char* to_table_end = _to_table + sizeof(_to_table); const char _from_table[128] = { -1, -1, -1, -1, -1, -1, -1, -1, // 0 -1, -1, -1, -1, -1, -1, -1, -1, // 8 -1, -1, -1, -1, -1, -1, -1, -1, // 16 -1, -1, -1, -1, -1, -1, -1, -1, // 24 -1, -1, -1, -1, -1, -1, -1, -1, // 32 -1, -1, -1, 62, -1, -1, -1, 63, // 40 52, 53, 54, 55, 56, 57, 58, 59, // 48 60, 61, -1, -1, -1, 0, -1, -1, // 56 -1, 0, 1, 2, 3, 4, 5, 6, // 64 7, 8, 9, 10, 11, 12, 13, 14, // 72 15, 16, 17, 18, 19, 20, 21, 22, // 80 23, 24, 25, -1, -1, -1, -1, -1, // 88 -1, 26, 27, 28, 29, 30, 31, 32, // 96 33, 34, 35, 36, 37, 38, 39, 40, // 104 41, 42, 43, 44, 45, 46, 47, 48, // 112 49, 50, 51, -1, -1, -1, -1, -1 // 120 }; const char* from_table = _from_table; }  

 

下面给一个test例子：

#include <iostream> #include <fstream> #include <iterator> #include <vector> #include <cstdlib> #include <cstring> #include "base64.hpp" using namespace std; int main() { const int size = 439; char source[size], source2[size]; vector<char> dest; int i; // initialize for(i=0; i < size; ++i) source[i] = (rand() & 0xFF); // convert to base64 base64::encode((char*)source, source+size, back_inserter(dest)); // spit out the result copy(dest.begin(), dest.end(), ostream_iterator<char>(cout)); cout << endl; // convert back to binary base64::decode(dest.begin(), dest.end(), source2); // make sure we got the same thing if (memcmp(source, source2, size) == 0) cout <<"They're the same!" << endl; else cout << "They're different!" << endl; // encode from memory to a file { ofstream file("b64.txt"); base64::encode((char*)source, source+size, ostream_iterator<char>(file)); } // decode from file to file { ifstream in("b64.txt"); ofstream out("b64.bin", ios::binary); base64::decode(istream_iterator<char>(in), istream_iterator<char>(), ostream_iterator<char>(out) ); } return 0; }  

 

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