这个Base64是从Live555的代码里面提取出来的，请大家放心使用吧。
Base64的加密解密的算法和原理我就不想说了。。。。， 网上有很多介绍原理的文章。
这个算法有啥好处呢？ 为什么我们要用它？
Base64算法不是为了防止内容被人破解而使用的算法， 因为破解Base64太容易了， 就是简单的字符替换。
Base64还有个不好的地方，就是加密后， 长度会变成。
那我们为何还要使用Base64 呢 ？ 因为Base64可以把乱七八糟的二进制转化为字符串，这个特性在很多地方很有用。
Base64.h 头文件
/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)
This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
more details.
You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
**********/
// "liveMedia"
// Copyright (c) 1996-2010 Live Networks, Inc. All rights reserved.
// Base64 encoding and decoding
// C++ header
#ifndef _BASE64_HH
#define _BASE64_HH
//#ifndef _BOOLEAN_HH
//#include "Boolean.hh"
//#endif
#ifdef __cplusplus
extern "C" {
#endif
unsigned char* base64Decode(char* in, unsigned int& resultSize, bool trimTrailingZeros = true);
// returns a newly allocated array - of size "resultSize" - that
// the caller is responsible for delete[]ing.
char* base64Encode(char const* orig, unsigned origLength);
// returns a 0-terminated string that
// the caller is responsible for delete[]ing.
#ifdef __cplusplus
}
#endif
#endif
Base64.cpp 文件
/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)
This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
more details.
You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
**********/
// "liveMedia"
// Copyright (c) 1996-2010 Live Networks, Inc. All rights reserved.
// Base64 encoding and decoding
// implementation
#include "base64.h"
#include <string.h>
static char base64DecodeTable[256];
char* strDup(char const* str)
{
if (str == NULL) return NULL;
size_t len = strlen(str) + 1;
char* copy = new char[len];
if (copy != NULL)
{
memcpy(copy, str, len);
}
return copy;
}
char* strDupSize(char const* str)
{
if (str == NULL) return NULL;
size_t len = strlen(str) + 1;
char* copy = new char[len];
return copy;
}
static void initBase64DecodeTable()
{
int i;
for (i = 0; i < 256; ++i) base64DecodeTable[i] = (char)0x80;
// default value: invalid
for (i = 'A'; i <= 'Z'; ++i) base64DecodeTable[i] = 0 + (i - 'A');
for (i = 'a'; i <= 'z'; ++i) base64DecodeTable[i] = 26 + (i - 'a');
for (i = '0'; i <= '9'; ++i) base64DecodeTable[i] = 52 + (i - '0');
base64DecodeTable[(unsigned char)'+'] = 62;
base64DecodeTable[(unsigned char)'/'] = 63;
base64DecodeTable[(unsigned char)'='] = 0;
}
unsigned char* base64Decode(char* in, unsigned int& resultSize, bool trimTrailingZeros)
{
static bool haveInitedBase64DecodeTable = false;
if (!haveInitedBase64DecodeTable)
{
initBase64DecodeTable();
haveInitedBase64DecodeTable = true;
}
unsigned char* out = (unsigned char*)strDupSize(in); // ensures we have enough space
int k = 0;
int const jMax = strlen(in) - 3;
// in case "in" is not a multiple of 4 bytes (although it should be)
for (int j = 0; j < jMax; j += 4)
{
char inTmp[4], outTmp[4];
for (int i = 0; i < 4; ++i)
{
inTmp[i] = in[i+j];
outTmp[i] = base64DecodeTable[(unsigned char)inTmp[i]];
if ((outTmp[i]&0x80) != 0) outTmp[i] = 0; // pretend the input was 'A'
}
out[k++] = (outTmp[0]<<2) | (outTmp[1]>>4);
out[k++] = (outTmp[1]<<4) | (outTmp[2]>>2);
out[k++] = (outTmp[2]<<6) | outTmp[3];
}
if (trimTrailingZeros)
{
while (k > 0 && out[k-1] == '/0') --k;
}
resultSize = k;
unsigned char* result = new unsigned char[resultSize];
memmove(result, out, resultSize);
delete[] out;
return result;
}
static const char base64Char[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
char* base64Encode(char const* origSigned, unsigned origLength)
{
unsigned char const* orig = (unsigned char const*)origSigned; // in case any input bytes have the MSB set
if (orig == NULL) return NULL;
unsigned const numOrig24BitValues = origLength/3;
bool havePadding = origLength > numOrig24BitValues*3;
bool havePadding2 = origLength == numOrig24BitValues*3 + 2;
unsigned const numResultBytes = 4*(numOrig24BitValues + havePadding);
char* result = new char[numResultBytes+1]; // allow for trailing '/0'
// Map each full group of 3 input bytes into 4 output base-64 characters:
unsigned i;
for (i = 0; i < numOrig24BitValues; ++i)
{
result[4*i+0] = base64Char[(orig[3*i]>>2)&0x3F];
result[4*i+1] = base64Char[(((orig[3*i]&0x3)<<4) | (orig[3*i+1]>>4))&0x3F];
result[4*i+2] = base64Char[((orig[3*i+1]<<2) | (orig[3*i+2]>>6))&0x3F];
result[4*i+3] = base64Char[orig[3*i+2]&0x3F];
}
// Now, take padding into account. (Note: i == numOrig24BitValues)
if (havePadding)
{
result[4*i+0] = base64Char[(orig[3*i]>>2)&0x3F];
if (havePadding2)
{
result[4*i+1] = base64Char[(((orig[3*i]&0x3)<<4) | (orig[3*i+1]>>4))&0x3F];
result[4*i+2] = base64Char[(orig[3*i+1]<<2)&0x3F];
}
else
{
result[4*i+1] = base64Char[((orig[3*i]&0x3)<<4)&0x3F];
result[4*i+2] = '=';
}
result[4*i+3] = '=';
}
result[numResultBytes] = '/0';
return result;
}