c++如何实现Base64算法
Base64用途
1.用于对SOHO级路由器（网关设备）管理员帐户密码的加密
2.流媒体网站对于播放的流媒体文件的路径的加密
3.迅雷等下载软件对下载链接地址的加密
Base64算法
Base64编码要求把3个8位字节（3*8=24）转化为4个6位的字节（4*6=24），之后在6位的前面补两个0，形成8位一个字节的形式。
Base64类
函数：
unsigned int CreateMatchingEncodingBuffer (unsigned int p_InputByteCount, char** p_ppEncodingBuffer);
创建匹配于编码的缓存空间。参数：1输入字节数，2进行编码需要的缓存空间；返回值：缓存空间大小。
unsigned int CreateMatchingDecodingBuffer (char* p_pInputBufferString, char** p_ppDecodingBuffer);
创建匹配于解码的缓存空间。参数：1解码对象缓存，2进行解码需要的缓存空间；返回值：缓存空间大小。
void EncodeBuffer (char* p_pInputBuffer, unsigned int p_InputBufferLength, char* p_pOutputBufferString);
进行编码。参数：1明文，2明文长度，3密文输出。
unsigned int DecodeBuffer (char* p_pInputBufferString, char* p_pOutputBuffer);
进行解码。参数：1密文，2明文；返回值：明文长度
C++实现：
头文件：
View Code
/************************************************
* *
* CBase64.h *
* Base 64 de- and encoding class *
* *
* ============================================ *
* *
* This class was written on 28.05.2003 *
* by Jan Raddatz [jan-raddatz@web.de] *
* *
* ============================================ *
* *
* Copyright (c) by Jan Raddatz *
* This class was published @ codeguru.com *
* 28.05.2003 *
* *
************************************************/
#pragma once
#include <afx.h>
#include <stdlib.h>
#include <math.h>
#include <memory.h>
const static unsigned int MAX_LINE_LENGTH = 76;
const static char BASE64_ALPHABET [64] =
{
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', // 0 - 9
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', // 10 - 19
'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', // 20 - 29
'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', // 30 - 39
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', // 40 - 49
'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', // 50 - 59
'8', '9', '+', '/' // 60 - 63
};
const static char BASE64_DEALPHABET [128] =
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0 - 9
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 10 - 19
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20 - 29
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 30 - 39
0, 0, 0, 62, 0, 0, 0, 63, 52, 53, // 40 - 49
54, 55, 56, 57, 58, 59, 60, 61, 0, 0, // 50 - 59
0, 61, 0, 0, 0, 0, 1, 2, 3, 4, // 60 - 69
5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 70 - 79
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 80 - 89
25, 0, 0, 0, 0, 0, 0, 26, 27, 28, // 90 - 99
29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // 100 - 109
39, 40, 41, 42, 43, 44, 45, 46, 47, 48, // 110 - 119
49, 50, 51, 0, 0, 0, 0, 0 // 120 - 127
};
enum
{
UNABLE_TO_OPEN_INPUT_FILE,
UNABLE_TO_OPEN_OUTPUT_FILE,
UNABLE_TO_CREATE_OUTPUTBUFFER
};
class CBase64
{
public:
CBase64 ();
unsigned int CalculateRecquiredEncodeOutputBufferSize (unsigned int p_InputByteCount);
unsigned int CalculateRecquiredDecodeOutputBufferSize (char* p_pInputBufferString);
void EncodeByteTriple (char* p_pInputBuffer, unsigned int InputCharacters, char* p_pOutputBuffer);
unsigned int DecodeByteQuartet (char* p_pInputBuffer, char* p_pOutputBuffer);
void EncodeBuffer (char* p_pInputBuffer, unsigned int p_InputBufferLength, char*p_pOutputBufferString);
unsigned int DecodeBuffer (char* p_pInputBufferString, char* p_pOutputBuffer);
unsigned int CreateMatchingEncodingBuffer (unsigned int p_InputByteCount, char** p_ppEncodingBuffer);
unsigned int CreateMatchingDecodingBuffer (char* p_pInputBufferString, char** p_ppDecodingBuffer);
unsigned int EncodeFile (char* p_pSourceFileName, char* p_pEncodedFileName);
unsigned int DecodeFile (char* p_pSourceFileName, char* p_pDecodedFileName);
};
cpp文件：
View Code
/************************************************
* *
* CBase64.cpp *
* Base 64 de- and encoding class *
* *
* ============================================ *
* *
* This class was written on 28.05.2003 *
* by Jan Raddatz [jan-raddatz@web.de] *
* *
* ============================================ *
* *
* Copyright (c) by Jan Raddatz *
* This class was published @ codeguru.com *
* 28.05.2003 *
* *
************************************************/
#include "stdafx.h"
#include "CBase64.h"
CBase64::CBase64 ()
{
}
unsigned int CBase64::CalculateRecquiredEncodeOutputBufferSize (unsigned int p_InputByteCount)
{
div_t result = div (p_InputByteCount, 3);
unsigned int RecquiredBytes = 0;
if (result.rem == 0)
{
// Number of encoded characters
RecquiredBytes = result.quot * 4;
// CRLF -> "\r\n" each 76 characters
result = div (RecquiredBytes, 76);
RecquiredBytes += result.quot * 2;
// Terminating null for the Encoded String
RecquiredBytes += 1;
return RecquiredBytes;
}
else
{
// Number of encoded characters
RecquiredBytes = result.quot * 4 + 4;
// CRLF -> "\r\n" each 76 characters
result = div (RecquiredBytes, 76);
RecquiredBytes += result.quot * 2;
// Terminating null for the Encoded String
RecquiredBytes += 1;
return RecquiredBytes;
}
}
unsigned int CBase64::CalculateRecquiredDecodeOutputBufferSize (char* p_pInputBufferString)
{
unsigned int BufferLength = strlen (p_pInputBufferString);
div_t result = div (BufferLength, 4);
if (p_pInputBufferString [BufferLength - 1] != '=')
{
return result.quot * 3;
}
else
{
if (p_pInputBufferString [BufferLength - 2] == '=')
{
return result.quot * 3 - 2;
}
else
{
return result.quot * 3 - 1;
}
}
}
void CBase64::EncodeByteTriple (char* p_pInputBuffer, unsigned int InputCharacters, char* p_pOutputBuffer)
{
unsigned int mask = 0xfc000000;
unsigned int buffer = 0;
char* temp = (char*) &buffer;
temp [3] = p_pInputBuffer [0];
if (InputCharacters > 1)
temp [2] = p_pInputBuffer [1];
if (InputCharacters > 2)
temp [1] = p_pInputBuffer [2];
switch (InputCharacters)
{
case 3:
{
p_pOutputBuffer [0] = BASE64_ALPHABET [(buffer & mask) >> 26];
buffer = buffer << 6;
p_pOutputBuffer [1] = BASE64_ALPHABET [(buffer & mask) >> 26];
buffer = buffer << 6;
p_pOutputBuffer [2] = BASE64_ALPHABET [(buffer & mask) >> 26];
buffer = buffer << 6;
p_pOutputBuffer [3] = BASE64_ALPHABET [(buffer & mask) >> 26];
break;
}
case 2:
{
p_pOutputBuffer [0] = BASE64_ALPHABET [(buffer & mask) >> 26];
buffer = buffer << 6;
p_pOutputBuffer [1] = BASE64_ALPHABET [(buffer & mask) >> 26];
buffer = buffer << 6;
p_pOutputBuffer [2] = BASE64_ALPHABET [(buffer & mask) >> 26];
p_pOutputBuffer [3] = '=';
break;
}
case 1:
{
p_pOutputBuffer [0] = BASE64_ALPHABET [(buffer & mask) >> 26];
buffer = buffer << 6;
p_pOutputBuffer [1] = BASE64_ALPHABET [(buffer & mask) >> 26];
p_pOutputBuffer [2] = '=';
p_pOutputBuffer [3] = '=';
break;
}
}
}
unsigned int CBase64::DecodeByteQuartet (char* p_pInputBuffer, char* p_pOutputBuffer)
{
unsigned int buffer = 0;
if (p_pInputBuffer[3] == '=')
{
if (p_pInputBuffer[2] == '=')
{
buffer = (buffer | BASE64_DEALPHABET [p_pInputBuffer[0]]) << 6;
buffer = (buffer | BASE64_DEALPHABET [p_pInputBuffer[1]]) << 6;
buffer = buffer << 14;
char* temp = (char*) &buffer;
p_pOutputBuffer [0] = temp [3];
return 1;
}
else
{
buffer = (buffer | BASE64_DEALPHABET [p_pInputBuffer[0]]) << 6;
buffer = (buffer | BASE64_DEALPHABET [p_pInputBuffer[1]]) << 6;
buffer = (buffer | BASE64_DEALPHABET [p_pInputBuffer[2]]) << 6;
buffer = buffer << 8;
char* temp = (char*) &buffer;
p_pOutputBuffer [0] = temp [3];
p_pOutputBuffer [1] = temp [2];
return 2;
}
}
else
{
buffer = (buffer | BASE64_DEALPHABET [p_pInputBuffer[0]]) << 6;
buffer = (buffer | BASE64_DEALPHABET [p_pInputBuffer[1]]) << 6;
buffer = (buffer | BASE64_DEALPHABET [p_pInputBuffer[2]]) << 6;
buffer = (buffer | BASE64_DEALPHABET [p_pInputBuffer[3]]) << 6;
buffer = buffer << 2;
char* temp = (char*) &buffer;
p_pOutputBuffer [0] = temp [3];
p_pOutputBuffer [1] = temp [2];
p_pOutputBuffer [2] = temp [1];
return 3;
}
return -1;
}
void CBase64::EncodeBuffer(char* p_pInputBuffer, unsigned int p_InputBufferLength, char* p_pOutputBufferString)
{
unsigned int FinishedByteQuartetsPerLine = 0;
unsigned int InputBufferIndex = 0;
unsigned int OutputBufferIndex = 0;
memset (p_pOutputBufferString, 0, CalculateRecquiredEncodeOutputBufferSize (p_InputBufferLength));
while (InputBufferIndex < p_InputBufferLength)
{
if (p_InputBufferLength - InputBufferIndex <= 2)
{
FinishedByteQuartetsPerLine ++;
EncodeByteTriple (p_pInputBuffer + InputBufferIndex, p_InputBufferLength - InputBufferIndex, p_pOutputBufferString + OutputBufferIndex);
break;
}
else
{
FinishedByteQuartetsPerLine++;
EncodeByteTriple (p_pInputBuffer + InputBufferIndex, 3, p_pOutputBufferString + OutputBufferIndex);
InputBufferIndex += 3;
OutputBufferIndex += 4;
}
if (FinishedByteQuartetsPerLine == 19)
{
p_pOutputBufferString [OutputBufferIndex ] = '\r';
p_pOutputBufferString [OutputBufferIndex+1] = '\n';
p_pOutputBufferString += 2;
FinishedByteQuartetsPerLine = 0;
}
}
}
unsigned int CBase64::DecodeBuffer (char* p_pInputBufferString, char* p_pOutputBuffer)
{
unsigned int InputBufferIndex = 0;
unsigned int OutputBufferIndex = 0;
unsigned int InputBufferLength = strlen (p_pInputBufferString);
char ByteQuartet [4];
while (InputBufferIndex < InputBufferLength)
{
for (int i = 0; i < 4; i++)
{
ByteQuartet [i] = p_pInputBufferString [InputBufferIndex];
// Ignore all characters except the ones in BASE64_ALPHABET
if ((ByteQuartet [i] >= 48 && ByteQuartet [i] <= 57) ||
(ByteQuartet [i] >= 65 && ByteQuartet [i] <= 90) ||
(ByteQuartet [i] >= 97 && ByteQuartet [i] <= 122) ||
ByteQuartet [i] == '+' || ByteQuartet [i] == '/' || ByteQuartet [i] == '=')
{
}
else
{
// Invalid character
i--;
}
InputBufferIndex++;
}
OutputBufferIndex += DecodeByteQuartet (ByteQuartet, p_pOutputBuffer + OutputBufferIndex);
}
// OutputBufferIndex gives us the next position of the next decoded character
// inside our output buffer and thus represents the number of decoded characters
// in our buffer.
return OutputBufferIndex;
}
unsigned int CBase64::CreateMatchingEncodingBuffer (unsigned int p_InputByteCount, char** p_ppEncodingBuffer)
{
unsigned int Size = CalculateRecquiredEncodeOutputBufferSize (p_InputByteCount);
(*p_ppEncodingBuffer) = (char*) malloc (Size);
memset (*p_ppEncodingBuffer, 0, Size);
return Size;
}
unsigned int CBase64::CreateMatchingDecodingBuffer (char* p_pInputBufferString, char** p_ppDecodingBuffer)
{
unsigned int Size = CalculateRecquiredDecodeOutputBufferSize (p_pInputBufferString);
(*p_ppDecodingBuffer) = (char*) malloc (Size+1);
memset (*p_ppDecodingBuffer, 0, Size+1);
return Size+1;
}
unsigned int CBase64::EncodeFile (char* p_pSourceFileName, char* p_pEncodedFileName)
{
CFile InputFile;
CFile OutputFile;
if (!InputFile.Open (p_pSourceFileName, CFile::modeRead))
return UNABLE_TO_OPEN_INPUT_FILE;
if (!OutputFile.Open (p_pEncodedFileName, CFile::modeCreate|CFile::modeWrite))
return UNABLE_TO_OPEN_OUTPUT_FILE;
char InputBuffer [19 * 3];
char* pOutputBuffer;
CreateMatchingEncodingBuffer (sizeof (InputBuffer), &pOutputBuffer);
if (pOutputBuffer == 0)
return UNABLE_TO_CREATE_OUTPUTBUFFER;
unsigned int ReadBytes = 0;
while ((ReadBytes = InputFile.Read (InputBuffer, sizeof (InputBuffer))) != 0)
{
EncodeBuffer (InputBuffer, ReadBytes, pOutputBuffer);
OutputFile.Write (pOutputBuffer, strlen (pOutputBuffer));
}
OutputFile.Flush ();
OutputFile.Close ();
InputFile.Close ();
return 0;
}
unsigned int CBase64::DecodeFile (char* p_pSourceFileName, char* p_pDecodedFileName)
{
CStdioFile InputFile;
CFile OutputFile;
if (!InputFile.Open (p_pSourceFileName, CFile::modeRead))
return UNABLE_TO_OPEN_INPUT_FILE;
if (!OutputFile.Open (p_pDecodedFileName, CFile::modeCreate|CFile::modeWrite))
return UNABLE_TO_OPEN_OUTPUT_FILE;
CString InputBuffer;
char OutputBuffer[64];
unsigned int ReadBytes = 0;
while ((ReadBytes = InputFile.ReadString (InputBuffer)) != 0)
{
InputBuffer.Remove ('\r');
InputBuffer.Remove ('\n');
unsigned int DecodedBytes = DecodeBuffer ((LPTSTR) (LPCTSTR) InputBuffer, OutputBuffer);
OutputFile.Write (&OutputBuffer [0], DecodedBytes);
}
OutputFile.Flush ();
OutputFile.Close ();
InputFile.Close ();
return 0;
}
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