base64 加密解密

#include<iostream.h>
#include<string.h>
char base64EncodeChars[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
char base64DecodeChars[]=
{
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, 0, -1, -1,
-1, 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, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, -1
};

//参数1：in,被编码字符串
//参数2：out,编码后字符指针，必须有足够的长度
//参数3：in_len,被编码字符串的长度
void base64Encode(char*in,char*out,int in_len)
{
int i=0,index=0;
unsigned char c1,c2,c3;
while(i<in_len)
{
   c1=*(in+i);
   i++;
   if(i == in_len)
   {
    out[index++]= base64EncodeChars[(c1 & 0XFF)>> 2];
    out[index++]= base64EncodeChars[(c1 & 0X03) << 4];
    out[index++]= '=';
    out[index++]= '=';
    break;
   }

   c2=*(in+i);
   i++;
   if(i == in_len)
   {
    out[index++]= base64EncodeChars[(c1 & 0XFF)>>2];         
    out[index++]= base64EncodeChars[((c1 & 0X3)<< 4) | ((c2 & 0XF0) >> 4)];
    out[index++]= base64EncodeChars[(c2 & 0X0F) << 2];
    out[index++]= '=';
    break;
   }
  
   c3=*(in+i);
   i++;
   out[index++]= base64EncodeChars[(c1 & 0XFF) >> 2];
   out[index++]= base64EncodeChars[((c1 & 0X03)<< 4) | ((c2 & 0XF0) >> 4)];
   out[index++]= base64EncodeChars[((c2 & 0X0F) << 2) | ((c3 & 0XC0) >>6)];
   out[index++]= base64EncodeChars[c3 & 0X3F];
}
out[index]='\0';
}

//参数1：in,被解码字符串
//参数2：out,解码后字符指针，必须有足够的长度
//参数3：in_len,被解码字符串的长度
void base64Decode(char*in,char*out,int in_len)
{
int i=0,index=0;
unsigned char c1,c2,c3,c4;

if(in_len<4)
   return;

//检查被解码的字符串是否是base64编码的
for(int j=0;j<in_len;j++)
   if(in[j]<0||
    (unsigned char)in[j]>=128||
    base64DecodeChars[in[j] & 0XFF]==-1)
    return;

while(i<in_len)
{
   c1 = base64DecodeChars[in[i++] & 0XFF];
   c2 = base64DecodeChars[in[i++] & 0XFF];
   out[index++]= (c1 << 2) | ((c2 & 0X30) >> 4);
  
   c3 =in[i++];
   if (c3 == '=')
    break;
   c3 = base64DecodeChars[c3];
   out[index++]= ((c2 & 0XF) << 4) | ((c3 & 0X3C) >> 2);

   c4 =in[i++];
   if (c4 == '=')
    break;
   c4 = base64DecodeChars[c4];
   out[index++]= ((c3 & 0X03) << 6) | c4;
}
out[index]='\0';
}


void main()
{
char p[]="k我0地98中国5人o";
int p_len=strlen(p);
int q_len=p_len/3*4;
if(p_len%3!=0)
   q_len=q_len+4;

char *q=new char[q_len];  
cout<<p<<endl;
base64Encode(p,q,strlen(p));
cout<<q<<endl;

int r_len=q_len*3/4;
char *r=new char[r_len];
base64Decode(q,r,strlen(q));
cout<<r<<endl<<endl;

char temp[]="UExBWSBydHNwOi8vcXVpY2t0aW1lLnV2bS5lZHU6MTU1NC93YXcvd2RpMDVoczJiLm1vdiBSVFNQLzEuMA0KQ1NlcTogNA0KUmFuZ2U6IG5wdD0wLjAwMDAwMC0xODQ2LjMzMzMzMw0KeC1wcmVidWZmZXI6IG1heHRpbWU9Mi4wMDAwMDANCngtdHJhbnNwb3J0LW9wdGlvbnM6IGxhdGUtdG9sZXJhbmNlPTEwDQpTZXNzaW9uOiA4MTA3MTkwMzE4NDQwODE3Njk5DQpVc2VyLUFnZW50OiBRdWlja1RpbWUvNy42LjUgKHF0dmVyPTcuNi41O29zPVdpbmRvd3MgTlQgNS4xU2VydmljZSBQYWNrIDMpDQoNCg==";
char base[300];
base64Decode(temp,base,strlen(temp));
cout<<base<<endl;
}