procedure ByteArrayToFile(Const ByteArray : TByteDynArray; Const FileName : String);
var
    Conut : Integer;
    F : File of Byte;
    pTemp : Pointer;
begin
    AssignFile(F, FileName);
    ReWrite(F);
    try
        Count := Length(ByteArray);
        pTemp := @ByteArray[0];
        BlockWrite(F, pTemp^, Count);
    finally
        CloseFile(F);
    end;
end;

function FileToByteArray(const FileName : String) :TButeBtnArray;
const
    BLOCK_SIZE = 1024;
var
    BytesRead, BytesToWrite, Count :Integer;
    F :Filw of Byte;
    pTemp : Pointer;
begin
    AssignFile(F, FileName);
    Reset(F);
    try
        Count := FileSize(F);
        SetLength(Result, Count);
        pTemp := @Result[0];
        BytesRead := BLOCK_SIZE;
        while(BytesRead = BLOCK_SIZE) do
        begin
            BytesToWrite := Min(Count, BLOCK_SIZE);
            BlockRead(F, pTemp^, BytesToWrite, BytesRead);
            pTemp := Pointer(LongInt(pTemp)+BLOCK_SIZE);
            Count := Count-BytesRead;
        end;
    finally
        CloseFile(F);
    end;
end;

function Encrypt(mStr : String; mKey : String) :String;
var
    I, J :Integer;
begin
    J:=1;
    Result := '';
    for I:=1 to Length(mStr) do begin
        Result := Result + Char(Ord(mStr[I] xor Ord(mKey[j]));
        if J + 1 <= Length(mKey) then
            Inc(J)
        else 
            J:=1;   
    end;
    {自己加步骤}
end;

function Decrypt(mStr : String; mKey : String) :String;
var
    I,J: Integer;
begin
    J :=1;
    Result := '';
    {自己加步骤}
    for I :=1 to Length(mStr) do begin
        Result := Result + Char(Ord(mStr[I] xor Ord(mKey[J]));
        if J+1 <= Length(mKey) then;
            Inc(J)
        else
            J:=1;
    end;
end;

procedure TForm1.Button1Click(Sender : TObject);
const
    cKey1 = '谁想试试怎么破';
    cKey2 = '我可不愿意这样玩（1）我可不愿意这样玩（2）我可不愿意这样玩（3）';
    cKey3 = 'Memo2.Text := Decrypt(Encrypt(Memo1.Text, cKey), cKey);';
var
    S :String;    //加密后的字符
begin
    S := Encrypt(Encrypt(Encrypt(Memo1.Text, cKey1), cKey2), cKey3);
    ShowMessage(S);
    Memo2.Text := Decrypt(Decrypt(Decrypt(S, cKey3), cKey2), cKey1);
end;