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;

}

转载于:https://www.cnblogs.com/ggzss/archive/2011/06/10/2077271.html