base.c

base64编码c语言实现

/****************************************************************
 This is a sample routine of base64 algorithm.The goal is to 
 illustrate principles,so some details may be ignored.
 Author email:[e-mail]
*****************************************************************/
#include <stdio.h>
#include <string.h>
#include <malloc.h>
unsigned char EncodBuf[16]; 
unsigned char DecodBuf[12]; 

void encode(unsigned char *source,int srclen)
{
 int n,buflen,i,j;
 //unsigned char *buf;
 //buf=src;
 buflen=n=srclen;
 /*if(n%3!=0) 
 {
   buflen=n+3-n%3;
   buf=malloc(buflen);

  for(i=0;i<3-n%3;i++)
  {
	  buf[n+i]='=';		//末位补充
  }
   
 }*/
 //EncodBuf=malloc(buflen*4/3);
 for(i=0,j=0;i<buflen;i+=3,j+=4)
 {
	EncodBuf[j]=(source[i]>>2)&0x3f;
	EncodBuf[j+1]=((source[i]<<4) + (source[i+1]>>4))&0x3f;
	EncodBuf[j+2]=((source[i+1]<<2) + (source[i+2]>>6))&0x3f;
	EncodBuf[j+3]=source[i+2]&0x3F; 
 }

}

void decode(unsigned char *source,int srclen)
{
	int n,i,j;
	n=srclen;
	//DecodBuf=malloc(srclen*3/4);
	for(i=0,j=0;i<n;i+=4,j+=3)
	{
		DecodBuf[j]=(source[i]<<2) + ((source[i+1]&0x30)>>4);
		DecodBuf[j+1]=((source[i+1]&0x0F)<<4) + ((source[i+2]&0x3C)>>2);
		DecodBuf[j+2]=((source[i+2]&0x03)<<6) + source[i+3];
	}

}

void main()
{

 unsigned char src[12]={1,2,3,4,5,6,7,8,9,10,11,0};
 unsigned int i;

 encode(src,12); /* the second parameter must accord with the first one */
 decode(EncodBuf,16);

 for(i=0;i<12;i++)
 {
	printf("%02x ",src[i]);

 }
    printf("\n");

 for(i=0;i<16;i++)
 {
	printf("%02x ",EncodBuf[i]);
 }
 	printf("\n");

 for(i=0;i<12;i++)
 {
	printf("%02x ",DecodBuf[i]);
 }


}