TweetFollow Us on Twitter

Volume Number:2
Issue Number:7
Column Tag:Special Projects

Recovering Protected Basic Programs

By DB Cooper, Seattle, WA

True Recovery at Last!

How many times have you saved what you thought was a completed MS Basic program to disk in protected mode, only to discover that was your only copy and now you need to make some changes? Recovering from Basic's protected option has been a hotly contested struggle between Basic programmers and the interpreter, which until now, has yielded very little in the way of a practical solution. In past issues of MacTutor, various attempts have been published, but each of these required that you do something to your program before you protected it. What if you didn't remember to do the special thing first? You were out of luck. Until now. After studying Mike Steiner's "Rescuit Program" in the September 1985 issue of MacTutor, I have invented a way to recover any protected Basic program after it is protected without any requirement on the author before he saved it. In otherwords, you can now unprotect any protected program without thinking about it ahead of time. Simply run this Basic program and your back in business! I accomplished this by writing the program below named 'Rescure(b)', which overwrites the encrypted code for: {Merge "it":'} at the front of the protected program. Then I set up a second program named 'It' which is merged to the protected program and then copies the program from memory to a file. This second step is based on Mike Steiner's article.

Version 2.1 Different

Unfortunately, this scheme didn't work with programs in the Microsoft Basic 2.1 Format, so I started to experiment. I determined that version 2.1 uses a seperate location in memory to store the names of the variables. I couldn't figure out how to find this table in memory directly, so instead I added a new variable "TenZZZZZZZZZZ" to the end of the table by defining it in the program, and had the routine search for ten Z's in a row. Then the program back tracks until it hits a binary zero, which defines the beginning and end of the variables table. (This method has worked with all the programs I have rescued, but I wouldn't bank on it always being successful.)

Cleaning up Garbage

At this point I ran into still another problem. The rescued program list still showed garbage in the variable and label names about 50% of the time. I scratched my head some more before I finally realized that the main listing must end with an odd number of characters (or even, when the first character is removed after the program has been loaded). I put in a counter to check for oddness.

After this final fix, the program seems to run quite well. When a rescue is completed, the rescued program must then be saved at once by the operator or the program rescued will not show the proper icon and the list window may show garbage when entered from the Desktop. (I still don't know the reason for the latter. ) At any rate, when 'Rescue(b)' has run, it leaves the rescued program loaded in memory, so you can simply do a "Save As" and your program will be fully recovered.

Ideas on the Encryption Used

The encryption method involves three steps; First, the binary value from each field is added to an offset in the range 0 to 255. If the sum is greater than 255, then 256 is subtracted so as to be in the proper range. Next, a mask in the same range is operated on the value using the logical XOR operand. Finally a second, different offset is subtracted from the result. The final binary code is truncated to the proper range and written to the file. (Note that, properly written, the same routine can be used to encode and decode the binary data.) Each position has its own offsets and masks which are calculated in some manner I couldn't determine, but these parameters are always the same at a given position, regardless of the program encrypted.

Since {Merge "It":'} is overwritten at the beginning of the file being rescued, it is best to use a copy of the same for the rescue. I added a separate, temporary file to store the values that were overwritten. These are later restored by the subroutine "Rescue" and the result is saved with the program code in the file: 'filename.IMOK'.

Using Rescue(b)

The programs work with files saved in both version 2.0 and 2.1 but must be run under the same version of BASIC. Files in version 2.0 are not saved properly when run under version 2.1 and presumably version 2.0 will not load version 2.1 files. If you have protected version 2.0 programs and don't have a backup of BASIC version 2.0, you're out of luck!

The program 'Rescue(b)' as listed below will rescue any Binary Basic programs. To rescue Decimal programs, change the 'MSBC' to 'MSBB' where indicated in the source code and save the modified Rescue program as a Decimal program file (ie: 'Rescue(d)'.) The second program listed below, called 'It', need only be written once and saved as a text file, but it must have the name "It" and both the 'Rescue' program and the 'It' program must reside on the default disk that has the Basic interpreter on it.

To use the program, make a copy of a Basic program and save it in protected mode. Then run the program 'Rescue(b)'. A standard file dialog box will come up and ask for the name of your protected program. Then the selected program will be loaded into memory, the 'It' text program will be read in and merged to the protected program, and the de-protection will take place (allow a minute or two for this, nothing will happen on the screen yet.) When done, another dialog box will come up indicating the process is done. At this point, the unprotected program will be in memory. Go to the File menu and do a "Save As" under a new file name, then quit Basic and try running and listing your new program. It should both run and list normally.

Well, that's about it. I have successfully rescued about a dozen different programs I previously protected, both Binary and Decimal, and in both version 2.0 and 2.1. It works properly on a skinny Mac, so presumably it will work on the bigger machines. The Program 'It' searches for the binary code for 'Merge "It":' in memory, so it shouldn't matter what size your Mac is.

Too bad the folks at Microsoft didn't employ a Password scheme to allow program recovery, then all of this wouldn't have been necessary! As a precaution against disgruntled vendors, I am publishing this article under a pen name. Don't try to find me, as my name suggests, I'm gone!

'<<< This program must be run under the same BASIC
'<<< type & version number as the file being recovered.
'<<< Keep the file named 'It' on the drive with basic. 
'<<< Open temporary file to store values
OPEN "Garbage Bag" AS #1 LEN=174
FIELD #1,128 AS N$,2 AS I$,4 AS T$,2 AS L$,36 AS K$,2 AS B$
WINDOW 1,,(50,30)-(212,46),4
DIM Keep%(18)
'<<< Ask for protected Program to rescue.
PRINT "Select a file to rescue...";
'<<< (Use "MSBP" instead for decimal program.)
FIELD #2,2 AS H$
'<<< Determine version and set type.
'<<< Decode length field of first Program line.
GET #2,1:Type$="MSBC"
IF Pre%=247 OR Pre%=251 THEN Type$="MSBB"
  GET #2,2
  READ Offset1%,Mask%,Offset2%
  GOSUB Cryptor
'<<< Decode and store positions 5-22 of Program
RESTORE OtherLines
  GET #2,Place%
    READ Offset1%,Mask%,Offset2%
  GOSUB Cryptor
    IF I%=Total% AND I%<14 THEN Total%=Total%+Bite%
'<<< Write coded {MERGE "It":' } on Program
FOR I%=1 TO 5
  READ Convert%
  LSET H$=MKI$(Convert%)
  PUT #2,I%+2
'<<< Recode length of new first line
'<<< Note Offsets are reversed for recoding
RESTORE FirstLine:Code%=Total%
READ Offset2%,Mask%,Offset1%
GOSUB Cryptor
GET #2,2:A$=RIGHT$("00"+HEX$(CVI(H$)),4)
  LSET H$=MKI$(VAL("&H"+A$))
  PUT #2,2
'<<< Save old values to temporary file
  FOR I%=1 TO 18
  LSET T$=Type$
  LSET L$=MKI$(Keep%(0))
  LSET K$=Kp$
  LSET B$=MKI$(Pre%)
PUT #1,1
'<<< Print message, then chain to Program.
'<<< The file 'It' will then be merged to
'<<< the end of the Program.
WINDOW 1,,(160,110)-(345,174),2
PRINT "Now merging the file 'It' to"
PRINT "'"+ID$+"'"
PRINT "Please enter 'Rescue' in the"
PRINT "Command Window...";
'<<< Routine to code/decode protected file
  Bite%=Code% XOR Mask%
  DATA 118,27,244
  DATA 248,36,246,249,18,247,250,81,248
  DATA 251,59,249,252,87,250,253,44,251
  DATA 254,211,252,255,66,253,5,132,142
  DATA 22,106,223,55,82,179,56,214,180
  DATA 57,164,181,0,0,252,0,0,252
  DATA 60,164,184,61,108,185,62,209,186
  DATA &HD28E,&H4F25,&H1846,&HCF76,&H47CE

REM}|{ Required marker for end of listing!!!
'<<< Type into Basic and save on same drive, 
'<<< as Basic, as 'It', in Text  format.
DIM Keep%(18)
PRINT:PRINT "Rescue engaged!"
'<<< Find location of {MERGE "It":} in memory
  IF PEEK(Peekloc!)<>248 GOTO ScanMem
  Flag%=0:RESTORE Peekvals
  FOR I=1 TO 7
    READ J%:IF PEEK(Peekloc!+I)<>J% THEN Flag%=1
  IF Flag%=1 AND Peekloc!<127*1024 GOTO ScanMem
  DATA &H9E,&H20,&H22,&H49,&H74,&H22,&H3A
'<<< Recover decoded values and parameters
OPEN "Garbage Bag" AS #1 LEN=174
FIELD #1,128 AS N$,2 AS I$,4 AS T$,2 AS L$,36 AS k$,2 AS 
  GET #1,1
KILL "Garbage Bag"
'<<< Write beginning of file
  PRINT #1,CHR$(Pre%);
  PRINT #1,CHR$(PEEK(Peekloc!+1));
  PRINT #1,CHR$(Keep%(0));
  PRINT #1,CHR$(PEEK(Peekloc!+3));
  FOR I%=1 TO 18
    PRINT #1,CHR$(Keep%(I%));
'<<< Copy file until }|{ marker is reached, then
'<<< skip to rescue5 if Program is version 2.0
  PRINT #1,CHR$(PEEK(Peekloc!));
  IF PEEK(Peekloc!+2)<>&HAF THEN GOTO rescue1
  IF PEEK(Peekloc!+3)<>ASC("}") THEN Flag%=0
  IF PEEK(Peekloc!+4)<>ASC("|") THEN Flag%=0
  IF PEEK(Peekloc!+5)<>ASC("{") THEN Flag%=0
IF Flag%=0 GOTO rescue1
PRINT #1,CHR$(0);CHR$(0);
IF Pre%>&HF7 GOTO rescue5
'<<< Make listing an Odd length
IF (1 AND INT(Begin1!))=0 THEN PRINT #1,CHR$(0);
'<<< Find end of variable names using: TenZZZ...Z
'<<< This var MUST NOT appear anywhere else:
  IF PEEK(Peekloc!)<>ASC("Z") GOTO rescue3
  FOR I%=1 TO 9
    IF PEEK(Peekloc!+I%)<>ASC("Z") THEN Flag%=0
IF Flag%=0 GOTO rescue3
'<<< Backtrack to start of variables list.
  IF PEEK(Peekloc!-1)<>&H0 GOTO rescue4
'<<< If total listing is odd, skip first position.
IF (1 AND INT(Begin2!))=0 THEN Peekloc!=Peekloc!+1
'<<< Print Variables table, EXCEPT: TenZ...ZZ
  PRINT #1,CHR$(PEEK(Peekloc!));
PRINT "Voil"+CHR$(136)+"! Rescue Completed!"
  CLOSE #1
  NAME ID$ AS ID$,Type$
PRINT "Now loading into memory."
PRINT "Recommend you first use"
PRINT "'Save As' to save file...";
BEEP:FOR I%=1 TO 20000:NEXT I%

Community Search:
MacTech Search:

Software Updates via MacUpdate

Dash 3.4.0 - 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
AirRadar 3.1.9 - $9.95
With AirRadar, scanning for wireless networks is now easier and more personalized! It allows you to scan for open networks and tag them as favourites or filter them out. View detailed network... Read more
Printopia 2.1.22 - Share Mac printers wi...
Run Printopia on your Mac to share its printers to any capable iPhone, iPad or iPod Touch. Printopia will also add virtual printers, allowing you to save print-outs to your Mac and send to apps.... Read more
SteerMouse 5.0 - Powerful third-party mo...
SteerMouse is an advanced driver for USB and Bluetooth mice. It also supports Apple Mighty Mouse very well. SteerMouse can assign various functions to buttons that Apple's software does not allow,... Read more
Alarm Clock Pro 10.2.5 - $19.95
Alarm Clock Pro isn't just an ordinary alarm clock. Use it to wake you up in the morning, send and compose e-mails, remind you of appointments, randomize the iTunes selection, control an internet... Read more
Cocktail 10.1 - General maintenance and...
Cocktail is a general purpose utility for macOS that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
RapidWeaver 7.1.7 - Create template-base...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
MacCleanse 5.1.6 - $29.95
MacCleanse is the product of thousands of hours of intense research and development. It meticulously scans all of the nooks and crannies of a computer for unnecessary junk that can take up huge... Read more
Slack 2.3.0 - Collaborative communicatio...
Slack is a collaborative communication app that simplifies real-time messaging, archiving, and search for modern working teams. Version 2.3.0: Note: Now requires OS X 10.8 or later New The app... Read more
Firefox 49.0.2 - Fast, safe Web browser.
Firefox offers a fast, safe Web browsing experience. Browse quickly, securely, and effortlessly. With its industry-leading features, Firefox is the choice of Web development professionals and casual... Read more

Latest Forum Discussions

See All

4 addictive clicker games like Best Fien...
Clickers are passive games that take advantage of basic human psychology to suck you in, and they're totally unashamed of that. As long as you're aware that this game has been created to take hold of your brain and leave you perfectly content to... | Read more »
Smile Inc. Guide: How not to die on the...
As if Mondays weren't bad enough, at Smile Inc. you have to deal with giant killer donuts, massive hungry staplers, and blasting zones. It's not exactly a happy, thriving work environment. In fact, you'll be lucky to survive the nine to five.... | Read more »
Oh...Sir! The Insult Simulator (Games)
Oh...Sir! The Insult Simulator 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: | Read more »
WitchSpring2 (Games)
WitchSpring2 1.27 Device: iOS Universal Category: Games Price: $3.99, Version: 1.27 (iTunes) Description: This is the story of Luna, the Moonlight Witch as she sets out into the world. This is a sequel to Witch Spring. Witch Spring 2... | Read more »
4 popular apps getting a Halloween makeo...
'Tis the season for all things spooky. So much, so, in fact, that even apps are getting into the spirt of things, dressing up in costume and spreading jack o' lanterns all about the place. These updates bring frightening new character skins, scary... | Read more »
Pokémon GO celebrates Halloween with can...
The folks behind Pokémon GO have some exciting things planned for their Halloween celebration, the first in-game event since it launched back in July. Starting October 26 and ending on November 1, trainers will be running into large numbers of... | Read more »
Best Fiends Forever Guide: How to collec...
The fiendship in Seriously's hit Best Fiends has been upgraded this time around in Best Fiends Forever. It’s a fast-paced clicker with lots of color and style--kind of reminiscent of a ‘90s animal mascot game like Crash Bandicoot. The game... | Read more »
5 apps for the budding mixologist
Creating your own cocktails is something of an art form, requiring a knack for unique tastes and devising interesting combinations. It's easy to get started right in your own kitchen, though, even if you're a complete beginner. Try using one of... | Read more »
5 mobile strategy games to try when you...
Strategy enthusiasts everywhere are celebrating the release of Civilization VI this week, and so far everyone seems pretty satisfied with the first full release in the series since 2010. The series has always been about ultra-addictive gameplay... | Read more »
Popclaire talk to us about why The Virus...
Humanity has succumbed to a virus that’s spread throughout the world. Now the dead have risen with a hunger for human flesh, and all that remain are a few survivors. One of those survivors has just called you for help. That’s the plot in POPCLAIRE’... | Read more »

Price Scanner via

Apple refurbished 2015 13-inch MacBook Airs a...
Apple has Certified Refurbished 2015 13″ MacBook Airs available starting at $759. An Apple one-year warranty is included with each MacBook, and shipping is free: - 2015 13″ 1.6GHz/4GB/128GB MacBook... Read more
64GB Apple TV on sale for $159, save $40
Best Buy has the 64GB Apple TV on sale for $40 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store price may... Read more
EyeQue Introduces iOS And Android Based Advan...
Affordable vision technologies developers EyeQue have announced what they claim to be the world’s most advanced intelligent vision solution, pitched as enabling anyone, anywhere to easily and... Read more
Smartwatch Market Tanks, Declining 51.6% in 2...
The worldwide smartwatch market experienced a round of growing pains in the third quarter of 2016 (3Q16), resulting in a year-over-year decline in shipment volumes. According to data from the... Read more
CAZE announces Ultra Thin Glass Screen Protec...
Hong Kong based CAZE has announced its first ultra thin glass screen protector, the Glazz Pro for iPhone 7/7 Plus. Glazz Pro is made from chemically reinforced glass with an anti-fingerprint... Read more
11-inch MacBook Airs on sale for up to $120 o...
Newegg has 11″ MacBook Airs on sale for up to $120 off MSRP. Shipping is free: - 11″ 1.6GHz/128GB MacBook Air: $799.99 $100 off MSRP - 11″ 1.6GHz/256GB MacBook Air: $979 $120 off MSRP Read more
Up to $300 off Macs, $20 off iPads with Apple...
Purchase a new Mac or iPad using Apple’s Education Store and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free, and... Read more
Apple’s Thursday “Hello Again” Event A Largel...
KGI Securities analyst Ming-Chi Kuo, who has a strong record of Apple hardware prediction accuracy, forecasts in a new note to investors released late last week that a long-overdue redo of the... Read more
12-inch Retina MacBooks on sale for $100 off...
Amazon has 2016 12″ Apple Retina MacBooks on sale for $100 off MSRP. Shipping is free: - 12″ 1.1GHz Silver Retina MacBook: $1199.99 $100 off MSRP - 12″ 1.1GHz Gold Retina MacBook: $1199.99 $100 off... Read more
Save up to $600 with Apple refurbished Mac Pr...
Apple has Certified Refurbished Mac Pros available for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The following... Read more

Jobs Board

*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
*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 52812872 Houston, Texas, United States Posted: Oct. 18, 2016 Weekly Hours: 40.00 **Job Summary** As an Apple Solutions Read more
Lead *Apple* Solutions Consultant - Apple (...
# Lead Apple Solutions Consultant Job Number: 52812906 Houston, Texas, United States Posted: Oct. 18, 2016 Weekly Hours: 40.00 **Job Summary** The Lead ASC is an Read more
*Apple* Retail - Multiple Positions- Towson,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Software Engineering Intern: Integration / QA...
Job Summary Apple is currently seeking enthusiastic interns who can work full-time for a minimum of 12-weeks between Fall 2015 and Summer 2016. Our software Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.