function Decode(const S: AnsiString): AnsiString; 
const 
  Map: array[Char] of Byte = (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, 63, 52, 53, 
    54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0, 0, 0, 0, 0, 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, 0, 0, 0, 0, 0, 0, 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, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
    0); 
var 
  I: LongInt; 
begin 
  case Length(S) of 
    2:  
      begin 
        I := Map[S[1]] + (Map[S[2]] shl 6); 
        SetLength(Result, 1); 
        Move(I, Result[1], Length(Result)) 
      end; 
    3:  
      begin 
        I := Map[S[1]] + (Map[S[2]] shl 6) + (Map[S[3]] shl 12); 
        SetLength(Result, 2); 
        Move(I, Result[1], Length(Result)) 
      end; 
    4:  
      begin 
        I := Map[S[1]] + (Map[S[2]] shl 6) + (Map[S[3]] shl 12) + 
          (Map[S[4]] shl 18); 
        SetLength(Result, 3); 
        Move(I, Result[1], Length(Result)) 
      end 
  end 
end; 

function Encode(const S: AnsiString): AnsiString; 
const 
  Map: array[0..63] of Char = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' + 
    'abcdefghijklmnopqrstuvwxyz0123456789+/'; 
var 
  I: LongInt; 
begin 
  I := 0; 
  Move(S[1], I, Length(S)); 
  case Length(S) of 
    1: 
      Result := Map[I mod 64] + Map[(I shr 6) mod 64]; 
    2: 
      Result := Map[I mod 64] + Map[(I shr 6) mod 64] + 
        Map[(I shr 12) mod 64]; 
    3: 
      Result := Map[I mod 64] + Map[(I shr 6) mod 64] + 
        Map[(I shr 12) mod 64] + Map[(I shr 18) mod 64] 
  end 
end;
