BASE64编码

// Base 64 encoder / decoder

AnsiString Base64Encoder(AnsiString slToEnc)

      {

        //The Base64 Table

        const char Base64Table[64]=

          "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

        char * buftoenc = slToEnc.c_str();

        int bufsize = slToEnc.Length() + 1;

        char * encbuf = new char[slToEnc.Length() * 5];

        encbuf[0] = '\0';  int ilStrLen = -1;

        int i=0; int b64byte[5];

        unsigned char *buftemp;

        AnsiString slRetVal = EmptyStr;





        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) ilStrLen = bufsize*8/6;

        else if (fmod(bufsize,3)==1) ilStrLen = ((bufsize+2)*8/6)-2;

        else if (fmod(bufsize,3)==2) ilStrLen = ((bufsize+1)*8/6)-1;

        else ilStrLen = -1;

        if(ilStrLen> 0) slRetVal = AnsiString(encbuf).SubString(1, ilStrLen);

        if(encbuf != NULL) { delete encbuf; encbuf = NULL; }



        return slRetVal;

      }





      //-----------------------------------------------------------------------


      AnsiString Base64Decoder(AnsiString slToDec)
      {

        //Base64 Table
        const char Base64Table[64]=

          "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

        char * buftodec = slToDec.c_str();

        int bufsize = slToDec.Length() + 1;

        char * decbuf = new char[slToDec.Length() * 5];

        decbuf[0] = '\0';  int ilStrLen = -1;

        AnsiString slRetVal = EmptyStr;



        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) ilStrLen = bufsize*6/8;

        else if (fmod(bufsize,4)==1) ilStrLen = ((bufsize+3)*6/8)-3;

        else if (fmod(bufsize,4)==2) ilStrLen = ((bufsize+2)*6/8)-2;

        else if (fmod(bufsize,4)==3) ilStrLen = ((bufsize+1)*6/8)-1;

        else ilStrLen = -1;

        if(ilStrLen> 0) slRetVal = AnsiString(decbuf).SubString(1, ilStrLen);

        if(decbuf != NULL) { delete decbuf; decbuf = NULL; }

        return slRetVal;

      }