修改时间戳破解CRC32算法 - bruce shi

作者在 2010-01-25 13:09:12 发布以下内容

小弟收集的。呵呵。

dymcrc32 单元

unit DymCrc32;
interface
uses
  Windows,SysUtils,Classes;
var
  Table:Array[0..255] of DWORD;
  procedure GetCRC32File(FileName:string;var CRC32:DWORD);
  function GetCrc32Str(s: string; Seed: LongInt):string;
implementation
procedure MakeTable();
var
  i,j,Crc:integer;
begin
  for i:=0 to 255 do
    begin
      Crc:=i;
      for j:=0 to 7 do
        begin
          if (Crc and 1)<>0 then
            Crc:=(Crc shr 1) xor $EDB88320
          else
            Crc:=Crc shr 1;
        end;
      Table:=Crc;
    end;
end;
procedure GetCRC32File(FileName:string;var CRC32:DWORD);
var
  F:file;
  BytesRead:DWORD;
  Buffer:array[1..65521] of Byte;
  i:Word;
begin
  MakeTable();
  FileMode :=0;
  CRC32 :=$ffffffff;
  {$I-}
  AssignFile(F,FileName);
  Reset(F,1);
  if IoResult = 0 then
    begin
      repeat
      BlockRead(F,Buffer,Sizeof(Buffer),BytesRead);
      for i := 1 to BytesRead do
        CRC32 := (CRC32 shr 8) xor Table[Buffer xor (CRC32 and $000000ff)];
      until BytesRead = 0;
    end;
  CloseFile(F);
  {$I+}
  CRC32 := not CRC32;
end;

function GetCrc32Str(s: string; Seed: LongInt):string;
var
  Count: Integer;
  CrcVal: LongInt;
begin
  MakeTable();
  CrcVal := Seed;
  for Count := 1 to Length(s) do
    CrcVal := Table[Byte(CrcVal xor DWORD(Ord(s[Count])))] xor ((CrcVal shr 8) and $00FFFFFF);
  Result := IntToHex(not(CrcVal), 8);
end;
end.

DymMain 单元
unit DymMain;
interface
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DymCrc32, ComCtrls;
type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Button2: TButton;
    Edit2: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
var
  Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
begin
  Edit1.Text:=GetCrc32Str('0123456789',8);//这里取指定字符串的CRC32校验值;
end;
procedure TForm1.Button2Click(Sender: TObject);
var
  FileStr:String;
  crc: DWORD;
begin
  FileStr:=Application.ExeName;//这里取指定的文件的crc32校验值;
  GetCRC32File(FileStr,crc);
  if crc<>0 then
    Edit2.Text:=PChar(IntToHex(crc,8));
end;
end.