找到的 base64编解码实现

最新推荐文章于 2024-10-26 12:50:54 发布

ICode_xyz

最新推荐文章于 2024-10-26 12:50:54 发布

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分类专栏： C 文章标签： dst null fp output buffer system

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本文介绍了一个简单的Base64编码和解码实现方法。通过C++代码示例，展示了如何将原始数据转换为Base64字符串以及如何从Base64字符串还原回原始数据。该方法适用于文件或其他二进制数据的编码。

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// Base64Encode.cpp : 定义控制台应用程序的入口点。

#include "stdafx.h"

#include <string.h>

#include <stdlib.h>

#include <stdio.h>

#include <errno.h>

#define BASE64_PAD64 '='

char base64_alphabet[] = {'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', '+',

'/'};

unsigned char base64_suffix_map[256] = {

255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

255, 255, 255, 62, 255, 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255,

255, 255, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,

15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, 255, 26, 27, 28,

29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,

49, 50, 51, 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};

static char cmove_bits(unsigned char src, unsigned lnum, unsigned rnum) {

src <<= lnum;

src >>= rnum;

return src;

}

void encode(char *src, int src_len, char *dst);

char* base64_encode(const char *data);

char* base64_decode(const char *bdata);

int _tmain(int argc, _TCHAR* argv[])

{

char * src = "gaoxiao1_01.png,1+gaoxiao1_02.png,2+gaoxiao1_03.png,3+gaoxiao1_04.png,4+gaoxiao1_05.png,5+gaoxiao1_06.png,6+gaoxiao1_07.png,7+gaoxiao1_08.png,8";

char * des = "Z2FveGlhbzFfMDEucG5nLDErZ2FveGlhbzFfMDIucG5nLDIrZ2FveGlhbzFfMDMucG5nLDMrZ2FveGlhbzFfMDQucG5nLDQrZ2FveGlhbzFfMDUucG5nLDUrZ2FveGlhbzFfMDYucG5nLDYrZ2FveGlhbzFfMDcucG5nLDcrZ2FveGlhbzFfMDgucG5nLDgA";

char dst[1000] = {0};

FILE * fp;

size_t len = 0;

char * str1 = base64_encode(src);

char * str2 = base64_decode(des);

encode(src,(int)strlen(src),dst);

fopen_s(&fp,"64encode.txt","w");

len = strlen(str2);

fwrite(str2,1,len,fp);

fclose(fp);

printf("%s/n",dst);

free(str1);

free(str2);

system("pause");

return 0;

}

void encode(char *src, int src_len, char *dst)

{

int i = 0, j = 0;

char base64_map[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

for (; i < src_len - src_len % 3; i += 3)

{

dst[j++] = base64_map[(src[i] >> 2) & 0x3F];

dst[j++] = base64_map[((src[i] << 4) & 0x30) + ((src[i + 1] >> 4) & 0xF)];

dst[j++] = base64_map[((src[i + 1] << 2) & 0x3C) + ((src[i + 2] >> 6) & 0x3)];

dst[j++] = base64_map[src[i + 2] & 0x3F];

}

if (src_len % 3 == 1)

{

dst[j++] = base64_map[(src[i] >> 2) & 0x3F];

dst[j++] = base64_map[(src[i] << 4) & 0x30];

dst[j++] = '=';

}

else if (src_len % 3 == 2)

{

dst[j++] = base64_map[(src[i] >> 2) & 0x3F];

dst[j++] = base64_map[((src[i] << 4) & 0x30) + ((src[i + 1] >> 4) & 0xF)];

dst[j++] = base64_map[(src[i + 1] << 2) & 0x3C];

dst[j++] = '=';

}

dst[j] = '/0';

}

char* base64_encode(const char *data) {

char *ret, *retpos;

int m, padnum = 0, retsize, dlen = (int)strlen(data);

if(dlen == 0) return NULL;

/* Account the result buffer size and alloc the memory for it. */

if((dlen % 3) != 0)

padnum = 3 - dlen % 3;

retsize = (dlen + padnum) + ((dlen + padnum) * 1/3) + 1;

if((ret = (char *)malloc(retsize)) == NULL)

return NULL;

retpos = ret;

/* Starting to convert the originality characters to BASE64 chracaters.

Converting process keep to 4->6 principle. */

for(m = 0; m < (dlen + padnum); m += 3) {

/* When data is not suffice 24 bits then pad 0 and the empty place pad '='. */

*(retpos) = base64_alphabet[cmove_bits(*data, 0, 2)];

if(m == dlen + padnum - 3 && padnum != 0) { /* Whether the last bits-group suffice 24 bits. */

if(padnum == 1) { /* 16bit need pad one '='. */

*(retpos + 1) = base64_alphabet[cmove_bits(*data, 6, 2) + cmove_bits(*(data + 1), 0, 4)];

*(retpos + 2) = base64_alphabet[cmove_bits(*(data + 1), 4, 2)];

*(retpos + 3) = BASE64_PAD64;

} else if(padnum == 2) { /* 8bit need pad two'='. */

*(retpos + 1) = base64_alphabet[cmove_bits(*data, 6, 2)];

*(retpos + 2) = BASE64_PAD64;

*(retpos + 3) = BASE64_PAD64;

}

} else { /* 24bit normal. */

*(retpos + 1) = base64_alphabet[cmove_bits(*data, 6, 2) + cmove_bits(*(data + 1), 0, 4)];

*(retpos + 2) = base64_alphabet[cmove_bits(*(data + 1), 4, 2) + cmove_bits(*(data + 2), 0, 6)];

*(retpos + 3) = base64_alphabet[*(data + 2) & 0x3f];

}

retpos += 4;

data += 3;

}

ret[retsize - 1] =0;

return ret;

}

char* base64_decode(const char *bdata) {

char *ret = NULL, *retpos;

int m, padnum = 0, retsize, bdlen = (int)strlen(bdata);

if(bdlen == 0) return NULL;

if(bdlen % 4 != 0) return NULL;

/* Whether the data have invalid base-64 characters? */

for(m = 0; m < bdlen; ++m) {

if(bdata[m] != BASE64_PAD64 && base64_suffix_map[bdata[m]] == 255)

goto LEND;

}

/* Account the output size. */

if(bdata[bdlen - 1] == '=') padnum = 1;

if(bdata[bdlen - 1] == '=' && bdata[bdlen - 2] == '=') padnum = 2;

retsize = (bdlen - 4) - (bdlen - 4) / 4 + (3 - padnum) + 1;

ret = (char *)malloc(retsize);

if(ret == NULL)

return NULL;

retpos = ret;

/* Begging to decode. */

for(m = 0; m < bdlen; m += 4) {

*retpos = cmove_bits(base64_suffix_map[*bdata], 2, 0) + cmove_bits(base64_suffix_map[*(bdata + 1)], 0, 4);

if(m == bdlen - 4 && padnum != 0) { /* Only deal with last four bits. */

if(padnum == 1) /* Have one pad characters, only two availability characters. */

*(retpos + 1) = cmove_bits(base64_suffix_map[*(bdata + 1)], 4, 0) + cmove_bits(base64_suffix_map[*(bdata + 2)], 0, 2);

Have two pad characters, only two availability characters.

if(padnum == 2) {

}

retpos += 3 - padnum;

} else {

*(retpos + 1) = cmove_bits(base64_suffix_map[*(bdata + 1)], 4, 0) + cmove_bits(base64_suffix_map[*(bdata + 2)], 0, 2);

*(retpos + 2) = cmove_bits(base64_suffix_map[*(bdata + 2)], 6, 0) + base64_suffix_map[*(bdata + 3)];

retpos += 3;

}

bdata += 4;

}

ret[retsize - 1] = 0;

LEND: return ret;

}