김효원, 문학중년, Swindler, coolx 님의 홈페이지

Programming

No.

140

Name.

swindler

Subject.

base64 encode/decode

Main Cate.

C/C++

Sub Cate.

Date.

2005-07-06 11:10

Hit.

3300 (211.109....)

File.

Borland C++ Builder 에서 작성한 것임]

#include <math.h>

const char Base64Table[64]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int Base64Encode(const char *buftoenc,int bufsize,char *encbuf)
{
int i=0;
int b64byte[5];
unsigned char *buftemp;

buftemp=(unsigned char *)malloc(bufsize+2);
strcpy(buftemp,buftoenc);
if (fmod(bufsize,3)==1)
{
buftemp[bufsize]='\0';
buftemp[bufsize+1]='\0';
}
if (fmod(bufsize,3)==2)buftemp[bufsize]='\0';
while (i<bufsize)
{
b64byte[0]=buftemp[i]>>2;
b64byte[1]=((buftemp[i]&3)<<4)|(buftemp[i+1]>>4);
b64byte[2]=((buftemp[i+1]&0x0F)<<2)|(buftemp[i+2]>>6);
b64byte[3]=buftemp[i+2]&0x3F;
encbuf[i+(i/3)]=Base64Table[b64byte[0]];
encbuf[i+(i/3)+1]=Base64Table[b64byte[1]];
encbuf[i+(i/3)+2]=Base64Table[b64byte[2]];
encbuf[i+(i/3)+3]=Base64Table[b64byte[3]];
i+=3;
}
free(buftemp);
if (fmod(bufsize,3)==0)return bufsize*8/6;
if (fmod(bufsize,3)==1)return((bufsize+2)*8/6)-2;
if (fmod(bufsize,3)==2)return((bufsize+1)*8/6)-1;
return -1;
}
int Base64Decode(const char *buftodec,int bufsize,char *decbuf)
{
int i=0;
unsigned char binbyte[4];
int cpos[5];
unsigned char *buftemp;

buftemp=(unsigned char *)malloc(bufsize);
strcpy(buftemp,buftodec);
if (fmod(bufsize,4)==1)
{
buftemp[bufsize]='\0';
buftemp[bufsize+1]='\0';
buftemp[bufsize+2]='\0';
}
if (fmod(bufsize,4)==2)
{
buftemp[bufsize]='\0';
buftemp[bufsize+1]='\0';
}
if (fmod(bufsize,4)==3)buftemp[bufsize]='\0';
while (i<bufsize)
{
cpos[0]=strchr(Base64Table,buftemp[i])-Base64Table;
cpos[1]=strchr(Base64Table,buftemp[i+1])-Base64Table;
cpos[2]=strchr(Base64Table,buftemp[i+2])-Base64Table;
cpos[3]=strchr(Base64Table,buftemp[i+3])-Base64Table;
binbyte[0]=((cpos[0]<<2)|(cpos[1]>>4));
binbyte[1]=((cpos[1]<<4)|(cpos[2]>>2));
binbyte[2]=(((cpos[2]&0x03)<<6)|(cpos[3]&0x3f));
decbuf[i-(i/4)]=binbyte[0];
decbuf[i-(i/4)+1]=binbyte[1];
decbuf[i-(i/4)+2]=binbyte[2];
i+=4;
}
free(buftemp);
if (fmod(bufsize,4)==0)return bufsize*6/8;
if (fmod(bufsize,4)==1)return((bufsize+3)*6/8)-3;
if (fmod(bufsize,4)==2)return((bufsize+2)*6/8)-2;
if (fmod(bufsize,4)==3)return((bufsize+1)*6/8)-1;
return -1;
}

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