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.
 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Capture One 11.0.1.40 - RAW workflow sof...
Capture One is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 400 high-end cameras -- straight out of the box. It offers... Read more
Capture One 11.0.1.40 - RAW workflow sof...
Capture One is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 400 high-end cameras -- straight out of the box. It offers... Read more
GraphicConverter 10.5.4 - $39.95
GraphicConverter is an all-purpose image-editing program that can import 200 different graphic-based formats, edit the image, and export it to any of 80 available file formats. The high-end editing... Read more
Dash 4.1.3 - Instant search and offline...
Dash is an API documentation browser and code snippet manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
Microsoft OneNote 16.9 - Free digital no...
OneNote is your very own digital notebook. With OneNote, you can capture that flash of genius, that moment of inspiration, or that list of errands that's too important to forget. Whether you're at... Read more
DEVONthink Pro 2.9.17 - Knowledge base,...
Save 10% with our exclusive coupon code: MACUPDATE10 DEVONthink Pro is your essential assistant for today's world, where almost everything is digital. From shopping receipts to important research... Read more
OmniGraffle 7.6 - Create diagrams, flow...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more
iFinance 4.3.7 - Comprehensively manage...
iFinance allows you to keep track of your income and spending -- from your lunchbreak coffee to your new car -- in the most convenient and fastest way. Clearly arranged transaction lists of all your... Read more
Opera 50.0.2762.58 - High-performance We...
Opera is a fast and secure browser trusted by millions of users. With the intuitive interface, Speed Dial and visual bookmarks for organizing favorite sites, news feature with fresh, relevant content... Read more
Microsoft Office 2016 16.9 - Popular pro...
Microsoft Office 2016 - Unmistakably Office, designed for Mac. The new versions of Word, Excel, PowerPoint, Outlook and OneNote provide the best of both worlds for Mac users - the familiar Office... Read more

Latest Forum Discussions

See All

Around the Empire: What have you missed...
Around this time every week we're going to have a look at the comings and goings on the other sites in Steel Media's pocket-gaming empire. We'll round up the very best content you might have missed, so you're always going to be up to date with the... | Read more »
Everything about Hero Academy 2: Part 4...
In this part of our Hero Academy 2 guide, we're going to have a look at some of the tactics you're going to need to learn if you want to rise up the ranks. We're going to start off slow, then get more advanced in the next section. [Read more] | Read more »
All the best games on sale for iPhone an...
Another week has flown by. Sometimes it feels like the only truly unstoppable thing is time. Time will make dust of us all. But before it does, we should probably play as many awesome mobile videogames as we can. Am I right, or am I right? [Read... | Read more »
The 7 best games that came out for iPhon...
Well, it's that time of the week. You know what I mean. You know exactly what I mean. It's the time of the week when we take a look at the best games that have landed on the App Store over the past seven days. And there are some real doozies here... | Read more »
Popular MMO Strategy game Lords Mobile i...
Delve into the crowded halls of the Play Store and you’ll find mobile fantasy strategy MMOs-a-plenty. One that’s kicking off the new year in style however is IGG’s Lords Mobile, which has beaten out the fierce competition to receive Google Play’s... | Read more »
Blocky Racing is a funky and fresh new k...
Blocky Racing has zoomed onto the App Store and Google Play this week, bringing with it plenty of classic kart racing shenanigans that will take you straight back to your childhood. If you’ve found yourself hooked on games like Mario Kart or Crash... | Read more »
Cytus II (Games)
Cytus II 1.0.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.1 (iTunes) Description: "Cytus II" is a music rhythm game created by Rayark Games. It's our fourth rhythm game title, following the footsteps of three... | Read more »
JYDGE (Games)
JYDGE 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Build your JYDGE. Enter Edenbyrg. Get out alive. JYDGE is a lawful but awful roguehate top-down shooter where you get to build your... | Read more »
Tako Bubble guide - Tips and Tricks to S...
Tako Bubble is a pretty simple and fun puzzler, but the game can get downright devious with its puzzle design. If you insist on not paying for the game and want to manage your lives appropriately, check out these tips so you can avoid getting... | Read more »
Everything about Hero Academy 2 - The co...
It's fair to say we've spent a good deal of time on Hero Academy 2. So much so, that we think we're probably in a really good place to give you some advice about how to get the most out of the game. And in this guide, that's exactly what you're... | Read more »

Price Scanner via MacPrices.net

Deals on clearance 15″ Apple MacBook Pros wit...
B&H Photo has clearance 2016 15″ MacBook Pros available for up to $800 off original MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: – 15″ 2.7GHz Touch Bar MacBook Pro... Read more
Apple restocked Certified Refurbished 13″ Mac...
Apple has restocked a full line of Certified Refurbished 2017 13″ MacBook Airs starting at $849. An Apple one-year warranty is included with each MacBook, and shipping is free: – 13″ 1.8GHz/8GB/128GB... Read more
How to find the lowest prices on 2017 Apple M...
Apple has Certified Refurbished 13″ and 15″ 2017 MacBook Pros available for $200 to $420 off the cost of new models. Apple’s refurbished prices are the lowest available for each model from any... Read more
The lowest prices anywhere on Apple 12″ MacBo...
Apple has Certified Refurbished 2017 12″ Retina MacBooks available for $200-$240 off the cost of new models. Apple will include a standard one-year warranty with each MacBook, and shipping is free.... Read more
Apple now offering a full line of Certified R...
Apple is now offering Certified Refurbished 2017 10″ and 12″ iPad Pros for $100-$190 off MSRP, depending on the model. An Apple one-year warranty is included with each model, and shipping is free: –... Read more
27″ iMacs on sale for $100-$130 off MSRP, pay...
B&H Photo has 27″ iMacs on sale for $100-$130 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27″ 3.8GHz iMac (MNED2LL/A): $2199 $100 off MSRP – 27″ 3.... Read more
2.8GHz Mac mini on sale for $899, $100 off MS...
B&H Photo has the 2.8GHz Mac mini (model number MGEQ2LL/A) on sale for $899 including free shipping plus NY & NJ sales tax only. Their price is $100 off MSRP. Read more
Apple offers Certified Refurbished iPad minis...
Apple has Certified Refurbished 128GB iPad minis available today for $339 including free shipping. Apple’s standard one-year warranty is included. Their price is $60 off MSRP. Read more
Amazon offers 13″ 256GB MacBook Air for $1049...
Amazon has the 13″ 1.8GHz/256B #Apple #MacBook Air on sale today for $150 off MSRP including free shipping: – 13″ 1.8GHz/256GB MacBook Air (MQD42LL/A): $1049.99, $150 off MSRP Read more
9.7-inch 2017 WiFi iPads on sale starting at...
B&H Photo has 9.7″ 2017 WiFi #Apple #iPads on sale for $30 off MSRP for a limited time. Shipping is free, and pay sales tax in NY & NJ only: – 32GB iPad WiFi: $299, $30 off – 128GB iPad WiFi... Read more

Jobs Board

*Apple* Retail - Multiple Positions - Apple,...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Data Center Site Selection and Strat...
# Apple Data Center Site Selection and Strategy Research Analyst Job Number: 83708609 Santa Clara Valley, California, United States Posted: 18-Jan-2018 Weekly Hours: Read more
Security Engineering Coordinator, *Apple* R...
# Security Engineering Coordinator, Apple Retail Job Number: 113237456 Santa Clara Valley, California, United States Posted: 18-Jan-2018 Weekly Hours: 40.00 **Job Read more
Firmware Engineer - *Apple* Accessories - A...
# Firmware Engineer - Apple Accessories Job Number: 113422485 Santa Clara Valley, California, United States Posted: 18-Jan-2018 Weekly Hours: 40.00 **Job Summary** Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.