怎样对文件进行加密和解密

Question

用DES或3DES吧！不过好像加密数据长度有限制！

Answer 1

就用DES加密
我有源代码，用C++Bullder写的。不过可以转成Delphi。

Answer 2

下面是我的代码，太简陋，各位老大不要笑话，权当抛砖引玉
procedure TForm1.Button1Click(Sender: TObject);
var i,j,totalcount:integer;
    filestream:Tfilestream;
    filename:string;
    tmpAsc:integer;
    buffer:string;
    buffersize:integer;
begin
opendialog1.Filter :='';
if not opendialog1.Execute then exit;
filename:=opendialog1.FileName ;
try
begin
  filestream:=Tfilestream.Create(filename,fmopenread);
  //把文件读入字符串变量
  buffersize:=filestream.Size ;
  setlength(buffer,buffersize);
  filestream.Read(pointer(buffer)^,buffersize);
  filestream.Free ;
  ///进行加密处理
  for i:=1 to buffersize do
  begin
    tmpasc:=ord(buffer[i]);
    tmpasc:=tmpasc xor 12;
    buffer[i]:=chr(tmpasc);
  end;
  //写回文件
  filestream:= tfilestream.Create(filename+'.mym',fmcreate);
  filestream.Write(pointer(buffer)^,buffersize);
  end;
  filestream.Free ;
except
  showmessage(inttostr(getlasterror));
end;
  showmessage('加密成功');
end;procedure TForm1.Button2Click(Sender: TObject);
var filename:string;
    filestream:Tfilestream;
    buffer:string;
    buffersize:integer;
    i:integer;
begin
opendialog1.Filter:=('加密文件|*.mym');
if not opendialog1.Execute then exit;
filename:=opendialog1.filename;
try
  ///读
  filestream:=Tfilestream.Create(filename,fmopenread);
  buffersize:=filestream.Size ;
  setlength(buffer,buffersize);
  filestream.Read(pointer(buffer)^,buffersize);
  filestream.Free ;
  //解密
  for i:=1 to buffersize do
  begin
    buffer[i]:=chr(ord(buffer[i]) xor 12);
  end;
  //写回
  filename:=copy(filename,1,length(filename)-4);
  filestream:=Tfilestream.Create(filename,fmcreate);
  filestream.Write(pointer(buffer)^,buffersize);
  filestream.free;
except
  showmessage(inttostr(getlasterror));
end;
showmessage('解密完成');
end;