base64.cpp

BASE64加解密

#include <stdio.h>

/*
*  对一段Buffer进行Base64编码
*
*	 	pSrc	输入Buffer
*		nSize	Buffer长度
*		pDest	输出缓冲
*
*	 注: 输出Buffer的长度可以使用 Base64EncodeSize(int) 方法取得
*/
static int base64_encode(char *pSrc, unsigned int nSize, char *pDest);

/*
*  对一段Buffer进行Base64解码
*	
*	 	pSrc	输入Buffer
*		nSize	Buffer长度
*		pDest	输出缓冲
*		return	解码后的实际长度
*
*	 注: 输出Buffer的长度可以使用 Base64DecodeSize(int) 方法取得
*/
static int  base64_decode(char *pSrc, unsigned int nSize, char *pDest);


//编码时候的每行的长度
unsigned int m_LineWidth = 76;	
	
//Base64解码表
const char BASE64_ENCODE_TABLE[64] = {
	 65,  66,  67,  68,  69,  70,  71,  72,  // 00 - 07
	 73,  74,  75,  76,  77,  78,  79,  80,  // 08 - 15
	 81,  82,  83,  84,  85,  86,  87,  88,  // 16 - 23
	 89,  90,  97,  98,  99, 100, 101, 102,  // 24 - 31
	103, 104, 105, 106, 107, 108, 109, 110,  // 32 - 39
	111, 112, 113, 114, 115, 116, 117, 118,  // 40 - 47
	119, 120, 121, 122,  48,  49,  50,  51,  // 48 - 55
	 52,  53,  54,  55,  56,  57,  43,  47 };// 56 - 63
	
	//Base64编码表
const unsigned int BASE64_DECODE_TABLE[256] = {
	255, 255, 255, 255, 255, 255, 255, 255, //  00 -  07
	255, 255, 255, 255, 255, 255, 255, 255, //  08 -  15
	255, 255, 255, 255, 255, 255, 255, 255, //  16 -  23
	255, 255, 255, 255, 255, 255, 255, 255, //  24 -  31
	255, 255, 255, 255, 255, 255, 255, 255, //  32 -  39
	255, 255, 255,  62, 255, 255, 255,  63, //  40 -  47
	 52,  53,  54,  55,  56,  57,  58,  59, //  48 -  55
	 60,  61, 255, 255, 255, 255, 255, 255, //  56 -  63
	255,   0,   1,   2,   3,   4,   5,   6, //  64 -  71
	  7,   8,   9,  10,  11,  12,  13,  14, //  72 -  79
	 15,  16,  17,  18,  19,  20,  21,  22, //  80 -  87
	 23,  24,  25, 255, 255, 255, 255, 255, //  88 -  95
	255,  26,  27,  28,  29,  30,  31,  32, //  96 - 103
	 33,  34,  35,  36,  37,  38,  39,  40, // 104 - 111
	 41,  42,  43,  44,  45,  46,  47,  48, // 112 - 119
	 49,  50,  51, 255, 255, 255, 255, 255, // 120 - 127
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255 };

//------------------------------------------------------------------------------
//获取Base64编码长度
int Base64EncodeSize(int iSize)
{
	int nSize, nCR;
	nSize = (iSize + 2) / 3 * 4 ;
	nCR = nSize / m_LineWidth; //计算回车数量
	nSize+= nCR * 2;
	return nSize;
}
	
//------------------------------------------------------------------------------
	
//获取Base64解码长度
int Base64DecodeSize(int iSize)
{
	return (iSize + 3) / 4 * 3;
}

	
//------------------------------------------------------------------------------	
//Base64编码
int base64_encode(char *pSrc, unsigned int nSize, char *pDest)
{
	if ((pSrc == NULL) || (nSize <= 0)) return 0;
		
	unsigned int iB, iInMax3, Len;
	char *pInPtr, *pInLimitPtr;
	char *OutPtr ;
			
	pInPtr = pSrc;
	iInMax3 = nSize / 3 * 3;
	OutPtr = pDest;
	pInLimitPtr = pInPtr + iInMax3;
				
	while (pInPtr != pInLimitPtr)
	{
		Len = 0;
		while ((Len < m_LineWidth) && (pInPtr != pInLimitPtr))
		{
			iB = (unsigned char) *pInPtr++;
			iB = iB << 8;
				
			iB = iB | (unsigned char) *pInPtr++;
			iB = iB << 8;
						
			iB = iB | (unsigned char) *pInPtr++;
						
			//以4 byte倒序写入输出缓冲
			OutPtr[3] = BASE64_ENCODE_TABLE[iB & 0x3F];
			iB = iB >> 6;
			OutPtr[2] = BASE64_ENCODE_TABLE[iB & 0x3F];
			iB = iB >> 6;
			OutPtr[1] = BASE64_ENCODE_TABLE[iB & 0x3F];
			iB = iB >> 6;
			OutPtr[0] = BASE64_ENCODE_TABLE[iB];
			OutPtr+=4;
			Len+=4;
		}
		if (Len >= m_LineWidth)
		{
			*OutPtr++ = '\r'; //加上回车换行符
			*OutPtr++ = '\n';
		}
	}
	//设置尾部
	switch (nSize - iInMax3)
	{
		case 1:
			iB = (unsigned char) *pInPtr;
			iB = iB << 4;
			OutPtr[1] = BASE64_ENCODE_TABLE[iB & 0x3F];
			iB = iB >> 6;
			OutPtr[0] = BASE64_ENCODE_TABLE[iB];
			OutPtr[2] = '='; //用'='也就是64码填充剩余部分
			OutPtr[3] = '=';
			OutPtr+=4;
			break;
		case 2:
			iB = (unsigned char) *pInPtr++;
			iB = iB << 8;
			iB = iB | (unsigned char) *pInPtr;
			iB = iB << 2;
			OutPtr[2] = BASE64_ENCODE_TABLE[iB & 0x3F];
			iB = iB >> 6;
			OutPtr[1] = BASE64_ENCODE_TABLE[iB & 0x3F];
			iB = iB >> 6;
			OutPtr[0] = BASE64_ENCODE_TABLE[iB];
			OutPtr[3] = '='; // Fill remaining byte.
			OutPtr+=4;
			break;
	}
	return (unsigned int) (OutPtr - pDest);
}

		
//------------------------------------------------------------------------------
//Base64解码
int base64_decode(char *pSrc, unsigned int nSize, char *pDest)
{
	if ((pSrc == NULL) || (pDest == NULL) || (nSize <= 0)) return 0;
			
	unsigned int lByteBuffer, lByteBufferSpace;
	unsigned int C; //临时阅读变量
	int reallen;
	char *InPtr, *InLimitPtr;
	char *OutPtr;
				
	lByteBuffer = 0; lByteBufferSpace = 4;
				
	InPtr = pSrc;
	InLimitPtr= InPtr + nSize;
	OutPtr = pDest;
				
	while (InPtr != InLimitPtr)
	{
		C = BASE64_DECODE_TABLE[*InPtr]; // Read from InputBuffer.
		InPtr++;
		if (C == 0xFF) continue; //读到255非法字符
		lByteBuffer = lByteBuffer << 6 ;
		lByteBuffer = lByteBuffer | C ;
		lByteBufferSpace--;
		if (lByteBufferSpace != 0) continue; //一次读入4个字节
		//到序写入3个字节到缓冲
		OutPtr[2] = lByteBuffer;
		lByteBuffer = lByteBuffer >> 8;
		OutPtr[1] = lByteBuffer;
		lByteBuffer = lByteBuffer >> 8;
		OutPtr[0] = lByteBuffer;
		//准备写入后3位
		OutPtr+= 3; lByteBuffer = 0; lByteBufferSpace = 4;
	}
	reallen = (unsigned int)OutPtr - (unsigned int)pDest;
	//处理尾部 返回实际长度
	switch (lByteBufferSpace)
	{
		case 1:
			lByteBuffer = lByteBuffer >> 2;
			OutPtr[1] = lByteBuffer;
			lByteBuffer = lByteBuffer >> 8;
			OutPtr[0] = lByteBuffer;
			return reallen + 2;
		case 2:
			lByteBuffer = lByteBuffer >> 4;
			OutPtr[0] = lByteBuffer;
			return reallen + 1;
		default:
			return reallen;
	}
}





int main()
{


	return 0;
}