TweetFollow Us on Twitter

Rescue
Volume Number:1
Issue Number:10
Column Tag:Special Projects

"Rescue that Protected Basic Program!"

By Mike Steiner, Sierra Vista, AZ., MacTutor Contributing Editor

In my diggings into Microsoft BASIC, I found some interesting things about how a program is stored on disk. My ultimate aim is to be able to “crack” a protected BASIC program; I once lost a program because I had saved it as protected and did not have an unprotected back-up copy.

The information in this column is valid only for BASIC Version 2.0; the discussion and program are not valid for Version 2.1. Most of the data presented in ‘MS BASIC Tokens Explained’ in the July 1985 Mactutor do not apply to Version 2.1. Also, the program is for a 512K Macintosh. Change the starting memory location (Peekloc) for a 128K or 1024K Macintosh as described in ‘MS BASIC Tokens Explained.’

Each version of BASIC (Binary and Decimal) is coded so that the finder treats them as two different creators. This, I assume, is because of the incompatabilities between the two versions. See last month's discussion of how numbers are stored in the two versions.

Fig. 1 How Rescuit Works

Table 1 shows the creators, file types, and ID bytes of the various files used by Microsoft BASIC version 2.0. (See sidebar for a brief explanation of creators and file-tpes.) The four-letter codes in parentheses on the top line of the table are the identification of the creators of the files. The four-letter codes in the table show the file types. The hexadecimal numbers in parentheses show the first byte (ID byte) of the files. TEXT files do not have an ID byte.

Once a file is loaded, the ID byte tells BASIC whether the file is protected. TEXT files do not need an ID byte because BASIC knows it is a text file and loads it in as is, translating reserved words into their hexadecimal tokens. BASIC can load any text file and treat it as a program listing (sometimes with curious results if the file is not a program). Each version (binary or decimal) can load compressed and protected files that were created only by itself. However, you can use SetFile to change the creator ID to load a file from the ‘other’ BASIC. If you do this, I recommend changing the ID byte with a disk zap program such as fEdit. Keep in mind that if there are any non-integer numbers defined in the program listing, their format will not be proper for the ‘new’ creator.

Protected programs, in addition to being having a unique TYPE and ID byte, are encyphered. It appears that this encyphering in only in the Macintosh version of Microsoft BASIC; friends with CP/M and MS DOS versions have not encrypted files with their versions of Microsoft BASIC. I have not yet been able to decypher these files; I have however, devised an interesting solution!

Following is a discussion of how you can prevent losing access to protected programs. The method discussed will not work on programs already protected; it will, however, give you a ‘back door’ into future programs. It works because when a protected program is loaded, it is decyphered and resides in memory as if it had been loaded from a text or compressed file. However, LIST, PEEK, and a slew of other commands are disabled in the command window. These commands have not been disabled from running from within the program, and that is what allows us to recover the file.

Listing 1 is a subprogram called "rescueit" which may be appended to any program prior to saving it as protected. Save rescueit as a TEXT file and MERGE it to your program. To use it, type the name of the subprogram in the command window, answer one question, and wait until it says that it is finished. (The name of the subprogram is in effect a password, so I strongly recommend that you change it to a name that only you know; otherwise anyone who knows it can recover your program.) Your program will be saved as a file called “Ressurected.”

Rescueit asks whether you are using Binary or Decimal BASIC. It then opens a file called “res” for output and then PRINTs one byte (the ID byte for a compressed program in the version of BASIC you are using) to the file. It then PEEKs the program in memory and PRINTs it to res, one byte at a time. It then PRINTs five zeroes at the end of the file. Read ‘MS BASIC Tokens Explained’ to see why this is necessary. After closing res, rescueit renames “res” as “Ressurected” and changes the filetype from TEXT to MSBC or MSBB, as appropriate. Then it prints “finished..” on the screen and exits to the desktop. Calling a sub-program from the command window sometimes scrambles pointers and causes memory problems. By exiting to the finder, these problems are avoided. The next step is to re-enter BASIC, load “Ressurected” using the Standard File and save the program. The program is now saved in compressed mode, ready to run or be edited. This last step sets the creator. If this step is omitted, the program will still load and run, but only from within BASIC; the finder will not recongnize an application to run the program if it is double-clicked, and the file will have the generic document icon. The only difference between ressurected and the original program is that ressurected has an extra blank line at the end of the listing. If you understand how BASIC stores programs in memory, you should be able to figure out why this is so. The reason is printed in a question / answer session at the end of this article.

Use of the program is fairly straightforward. Assuming that you already have rescuit on your disk (Remember to save it as a text file, not as a compressed program.), write your program and save it as a text or compressed file. (Don't forget to always keep a backup file!) In the command window, type “Merge "rescueit".” This will cause rescueit to be appended to the end of your program. Then choose “Save As ” from the File menu. Save your program (with rescueit appended) as a protected program. Now, if you ever lose your backup and need to recover the protected file, load BASIC and open the protected file. Within the command window, type resuceit (or the name to which you renamed the sub-program). The routine will execute, and when it ends will tell you that it is finished and return to the desktop. Next, set the creator as described above. Whenever you use rescueit, start with the Macintosh turned off. As discussed in ‘MS BASIC Tokens Explained,’ if another application has been run before BASIC, sometimes BASIC programs do not load at the same memory location. Rescueit always assumes that the program loads at the same point. Illustration 1 is a brief schematic of the rescueit process.

File Types and Creator Bytes

File-type and creator (also called file-type and creator flags) are four-letter abbreviations that show the file type and which application generated the file. An application (i.e. a program that can be run by double-clicking it's icon on the desktop) is a file that always has the file-type APPL. All other files are known as ‘Documents’ and may have any file-type that the programmer chooses.

Applications without a defined icon use the generic application icon (the diamond-shaped paper with a hand writing on it). Documents without a defined icon use the generic document icon (a piece of blank paper with the upper right corner folded down).

The finder uses the file type and creator flags to know which document files can be loaded by a given application. A document is linked to it's creator by the creator flag. When a document and a program have the same creator, the finder knows to launch that program when you double click on the document icon; once the program is launched, the finder tells it to open the document. The file type flag has a number of purposes. The most common is to assign an icon to the file. All the desk-top icons used by a program are stored in it's ICN# resource. The finder uses the type and creator flags to assign the correct icon to the file. (However, for ducument files, a bit in the application called the bundle bit must be set to 1; otherwise, the link is not established.) Also, the Standard File (which contains the list of documents that you can open when you choose Open from the File menu within a program) uses the file type to determine which files may be opened. These files are not restricted to those created by the application; for example, Microsoft Word can open files created by Apple's Macwrite. However, you cannot open a Macwrite document with Word by double-clicking the document icon; you can only do it from within Word via the Standard File.

Two interesting features of Microsoft BASIC are that you can specify file types when loading a file from within a program by use of the FILE$(1) function; by using the NAME command, you can change the file-type of a file on the disk. Rescueit makes use of this latter feature to change the rescued program from a TEXT file to a BASIC compressed file; this step is necessary because the file is generated in the compressed format, but saved as a TEXT file.

So far as I have been able to determine, there is no way for a Microsoft BASIC program to determine which version of BASIC it is using. The prefix byte exists only on the disk, and is not stored in memory; FILES$(1) can read the file type, but not the creator; NAME likewise can change only the file type and name. Does anyone know how to read or set the creator of a file from within MS BASIC? MacTutor will pay $50 to the first submission that shows how to do it.

Table 1

Microsoft BASIC 2.0 Creator and File Type Codes

Mode Binary (MSBB) Decimal (MSBA)

Text TEXT TEXT

Compressed MSBC (F9) MSBB (FB)

Protected MSBD (F8) MSBP (FA)

Listing 1 - Rescueit

REM }|{ Marker for end of main program - don't change!!
SUB rescueit STATIC: REM Change the name “rescueit” of sub-program for 
password protection

prefixbyte(1) = &HF9:prefixbyte(2) = &HFB
filetype$(1) = "MSBC":filetype$(2) = "MSBB"
Peekloc(1) = 66999!: Peekloc(2) = 77001!

WINDOW 1,,(100,100)-(400,200),2
TEXTFONT 0
PRINT "  Which version of BASIC are you using?"
TEXTFONT 1
BUTTON 1,1,"Binary",(35,40)-(95,65)
BUTTON 2,1,"Decimal",(170,40)-(240,65)
WHILE DIALOG (0)<>1:WEND
buttonpressed = DIALOG (1)
Peekloc = Peekloc(buttonpressed)

WINDOW 1,"rescuit",(2,39)-(508,338),1
OPEN "res" FOR OUTPUT AS #1
PRINT#1,CHR$(prefixbyte(buttonpressed));

rescue1:
peekloc = peekloc +1
IF PEEK (peekloc) = &HAF THEN IF PEEK  (peekloc+1) = &H20 AND PEEK (peekloc+2) 
 = ASC ("}") AND PEEK (peekloc+3) = ASC      ("|") AND PEEK (peekloc+4 
) = ASC ("{")  THEN rescue2: REM Find marker
PRINT #1, CHR$ (PEEK (peekloc));
GOTO rescue1

rescue2:
FOR j = 1 TO 4
 PRINT #1,CHR$(&H0);
NEXT j
CLOSE #1
NAME "res" AS "Resurrected", filetype$(buttonpressed)

CALL TEXTSIZE (127)
PRINT: PRINT "Finished..";
SYSTEM
END SUB

Q: "Why does rescuit add a line feed to the end of a file?"

A: When rescueit (or any other file) is merged to a program, it is appended to the end of the program, starting on a new line. This generates a carriage return after the last line of the program. Then when rescueit runs, it looks for the REM line that starts the rescueit routine, and saves the program up to the last byte before the REM. This last byte is the carriage return that was inserted when rescueit was merged. A carriage return at the end of a program is treated by BASIC as a blank line.

For What It's Worth Dept.

Peter Wollschlaeger of Hildeseim, West Germany, sent in this little gem. Try it, you'll like it! Peter says "...the most information I ever got for a Mac programmer like me in Macworld was an ad to subscribe to MacTutor!" Peter also reports that trying to run the MDS Editor under Finder version 3.3 bombs. Update to 4.1 Peter. Then your only problem will be missing icons occasionally! (See top column right.)

program Bugged;
var
 r :  rect;
 left, top, right, bottom : integer;
 icon1, icon2, width :  integer;
begin
 left := 10;
 top := 10;
 right := 40;
 bottom := 40;
 width := right - left + 10;
 icon1 := 1;
 icon2 := 257;

 showdrawing;
 setrect(r, left, top, right, bottom);
 ploticon(r, geticon(icon1));
 setrect(r, left + width, top, right + width, bottom);
 ploticon(r, geticon(icon2));
end.
 
AAPL
$524.94
Apple Inc.
+5.93
MSFT
$40.01
Microsoft Corpora
-0.39
GOOG
$536.10
Google Inc.
-20.44

MacTech Search:
Community Search:

Software Updates via MacUpdate

VMware Fusion 6.0.3 - Run Windows apps a...
VMware Fusion allows you to create a Virtual Machine on your Mac and run Windows (including Windows 8.1) and Windows software on your Mac. Run your favorite Windows applications alongside Mac... Read more
Tweetbot 1.5.1 - Popular iOS twitter cli...
Tweetbot is a full-featured OS X Twitter client with a lot of personality. Whether it's the meticulously-crafted interface, sounds and animation, or features like multiple timelines and column views... Read more
Mac DVDRipper Pro 4.1.7 - Copy, backup,...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
PDFpenPro 6.2 - Advanced PDF toolkit for...
PDFpenPro allows users to edit PDF's easily. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Create... Read more
PDFpen 6.2 - Edit and annotate PDFs with...
PDFpen allows users to easily edit PDF's. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Features... Read more
Monolingual 1.5.9 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Starcraft II: Wings of Liberty 1.1.1.180...
Download the patch by launching the Starcraft II game and downloading it through the Battle.net connection within the app. Starcraft II: Wings of Liberty is a strategy game played in real-time. You... Read more
Sibelius 7.5.0 - Music notation solution...
Sibelius is the world's best-selling music notation software for Mac. It is as intuitive to use as a pen, yet so powerful that it does most things in less than the blink of an eye. The demo includes... Read more
Typinator 5.9 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more

Latest Forum Discussions

See All

This Week at 148Apps: April 14-18, 2014
Spring Into Our App Reviews   | Read more »
Have a Special Dead Trigger 2 Easter Bas...
Have a Special Dead Trigger 2 Easter Basket Full of Goodies, Courtesy of Madfinger Games Posted by Rob Rich on April 18th, 2014 [ permalink ] Dead Trigger 2 | Read more »
Almost All of Playdek’s Library is on Sa...
Almost All of Playdek’s Library is on Sale Right Now, and You Should Check it Out Posted by Rob Rich on April 18th, 2014 [ permalink ] Playdek has released quite a few great iOS ports of board and card games over the years, and now most of them... | Read more »
Zynga Launches Brand New Farmville Exper...
Zynga Launches Brand New Farmville Experience with Farmville 2: Country Escape Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »
David. Review
David. Review By Cata Modorcea on April 18th, 2014 Our Rating: :: MINIMALISTIC IN A DIFFERENT WAYUniversal App - Designed for iPhone and iPad David is a minimalistic game wrapped inside of a soothing atmosphere in which the hero... | Read more »
Eyefi Unveils New Eyefi Cloud Service Th...
Eyefi Unveils New Eyefi Cloud Service That Allows Users to Share Media Across Personal Devices Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »
Tales from the Dragon Mountain: The Lair...
Tales from the Dragon Mountain: The Lair Review By Jennifer Allen on April 18th, 2014 Our Rating: :: STEADY ADVENTURINGiPad Only App - Designed for the iPad Treading a safe path, Tales from the Dragon Mountain: The Lair is a... | Read more »
Yahoo Updates Flickr App with Advanced E...
Yahoo Updates Flickr App with Advanced Editing Features and More Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »
My Incredible Body - A Kid's App to...
My Incredible Body - A Kid's App to Learn about the Human Body 1.1.00 Device: iOS Universal Category: Education Price: $2.99, Version: 1.1.00 (iTunes) Description: Wouldn’t it be cool to look inside yourself and see what was going on... | Read more »
Trials Frontier Review
Trials Frontier Review By Carter Dotson on April 18th, 2014 Our Rating: :: A ROUGH LANDINGUniversal App - Designed for iPhone and iPad Trials Frontier finally brings the famed stunt racing franchise to mobile, but how much does its... | Read more »

Price Scanner via MacPrices.net

Deal Alert! 13-inch MacBook Pro on sale for $...
Best Buy has the 13″ 2.5GHz MacBook Pro on sale for $999.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $200 off MSRP. Price is valid... Read more
Free HopTo 2.2 Helps Enhance Your Productivit...
The HopTo app helps you do more on your iPad by providing more and easier adaccess to files and documents. Version 2.2 adds Egnyte and HopTo’s Mac OSX File Connector. If you already have the hopTo... Read more
National Distracted Driving Awareness Month:...
As the country recognizes National Distracted Driving Awareness Month, Sprint is reminding wireless consumers to focus on driving while behind the wheel, to not text or email while driving, and to... Read more
13-inch 2.4GHz Retina MacBook Pro available f...
Abt has the 13″ 2.4GHz 128GB Retina MacBook Pro available for $1229 including free shipping. Their price is $70 off MSRP. Read more
iMacs on sale for up to $160 off MSRP this we...
Best Buy has iMacs on sale for up to $160 off MSRP for a limited time. Choose free home shipping or free instant local store pickup (if available). Prices are valid for online orders only, in-store... Read more
iPad Airs on sale this weekend for up to $100...
Best Buy has WiFi iPad Airs on sale for $50 off MSRP and WiFi + Cellular iPad Airs on sale for $100 off MSRP on their online store for a limited time, with prices now starting at $449. Choose free... Read more
Apple restocks refurbished Mac minis starting...
The Apple Store has restocked Apple Certified Refurbished Mac minis for up to $150 off the cost of new models. Apple’s one-year warranty is included with each mini, and shipping is free: - 2.5GHz Mac... Read more
Hyundai Brings Apple CarPlay To The 2015 Sona...
Hyundai Motor America has announced it will bring Apple CarPlay functionality to the 2015 Sonata. CarPlay is pitched as a smarter, safer and easier way to use iPhone in the car and gives iPhone users... Read more
Updated iPads Coming Sooner Than We Had Thoug...
MacRumors, cites KGI securities analyst Ming Chi Kuo, well-respected as an Apple product prognisticator, saying that Apple will introduce an upgraded iPad Air and iPad mini in 2014/Q3, meaning the... Read more
Toshiba Unveils New High And Low End Laptop M...
Toshiba has announced new laptop models covering both the high-end and low-end of the notebook computer spectrum. Toshiba 4K Ultra HD Laptop Toshiba’s new Satellite P55t features one of the world’s... Read more

Jobs Board

Position Opening at *Apple* - Apple (United...
…customers purchase our products, you're the one who helps them get more out of their new Apple technology. Your day in the Apple Store is filled with a range of Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Inc. Research Data Specialist - Appl...
…of Worldwide Market Research & Intelligence. The team is responsible for conducting Apple branded consumer market research. It is also responsible for analyzing data Read more
*Apple* Automotive Parts Department position...
Apple Automotive is one of the fastest growing dealer…and it shows. Consider making the switch to the Apple Automotive Group today! At Apple Automotive, we Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.