Master Index Current Directory Index Go to SkepticTank Go to Human Rights activist Keith Henson Go to Scientology cult

Skeptic Tank!

#44 : COPY PROTECTION 295 LINES - 59 SECTORS CONTRIBUTED BY DIAMOND JIM -----* COPY PROTECTING YOUR OWN DISKS BY THOMAS T. BRYLINSKI 08/04/82 INTRODUCTION: For those new-commers to the world of APPLE Computers, and to the history of software development, here is a brief summary. In ancient times (1978-1979), the APPLE Corporation was just getting started , and absolutely no software was available for your $1530 toy. So most people who bought this expensive little tan box had to write their own software. If you were among the more fortunate users who had a good sales pitch, you talked your boss into buying you an APPLE, and then spent your company's time learning the in's and out's of programming. In any case, you could not purchase ANY good software for your mac hine. Shortly after the first early programmers crawled out of their shells, APPLE users groups started to form. The prime function of these groups was to share programs and to exchange the secrets which one had learned in the previous month. (also it was a good excuse to get away from the kids at home, for a night)! Four or five months passed and a few early programmers got the idea that they would market their software and make a few bucks for their hard hours programming. And thus, the first APPLE soft ware companies formed. These companies were very small and usually started in someone's basement. The prime buyers of this software were the APPLE DEALERS. The dealers could now demonstrate these marvelous machines with some "GREAT" software. By the way, this great software came on cassettes, (you know, those little plastic things you used to record music on). These cassettes were copyable by normal means, (eg. tape recording), and the dealers started giving some programs away with each system that theys old. In the summer of the DARK AGES (1979), APPLE COMUPTER released their first d isk drive system (3.2 DOS). This disk system made copying programs easier, faster, and much more reliable. At this time copying was encouraged by both programmer and dealer. So on the software companies realized the increasing market for their products, and theorized that if they could produce a disk that could not be copied by normal means they could sell more software, hence more profit. APPLE'S disk system was the perfect answer to their problem. APPLE chose to make their disk system totally "SOFT", which means that all information pertaining to the disk operation is stored on disk . This information is then loaded into RAM (random access memory), upon a system boot (PR#6). All commands typed at the keyboard are examined by the "disk operating system" (DOS), and then by the apple ROM's (that row of big fat chips inside the machine). Now the software writers had an edge on the normal user, change how the APPLE responds to user commands, and keep them out of your programs. The only problem was that the copy program that came with your disk drive was able to copy the complete disk. With a "soft" DOS, the programmers could change how the information is read from disk and modify their DOS to read it. As Apple users became more aware of the internal workings of their machines, programmers made more and more changes to DOS, and the race was on! So much for the history lesson (boring out-of-date information anyway), and o n to the meat of the lecture. TERMS USED IN THE TEXT: BIT- the smallest piece of information that the computer can recognize or process. NIBBLE- four bits in a row, or a block BYTE- eight bits in a row or block. It is the smallest piece of information that people like to work with. (00000000) VTOC- Volume Table Of Contents: DOS uses this sector to tell it which sectors are used and which are free on the disk. SELF-SYNC BYTE- a special byte used for locating information on the disk. This byte differs from a normal byte in that it is made up of nine bits. (111111111) PROTECTION METHODS DISK COMMAND CHANGES- changes to the DOS that make those familiar words like Load, Delete, and Save, give the user that cold, unforgiving response...SYNTAX ERROR CATALOG TRACK LOCATION- moving the catalog to a non-standard track (normally track HEX $11, DEC 17) CHECKSUM ALTERATION- the portion of each sector that DOS automatically checks to make sure that the information it has read is correct. $D6,VECTOR- an Applesoft pointer used by the machine to make "carriage return" = RUN. LOADER DOS- a DOS whose sole purpose is to Load and execute one program from disk. HALF-TRACKING- writing information between the normal tracks on the disk. DOS HOOK- designating a specific track on the disk, where the only information on the track is a track & sector number, to tell DOS where to read next. PROGRAM LOCK- a line of programming that looks at a specific memory location and compares its contents to a programmed number. (x=peek(y)) HARDWARE LOCK- Using a hardware modification to lock the program. NIBBLE COUNTING- setting aside a specific track on the disk where a number of self-sync nibbles are written. TOOLS FOR LOCKING PROGRAMS DOS BOSS - Beagle Brothers Software BEANETH APPLE DOS - Quality Software PROGRAMMER'S AIDS - Dakin 5 Corporation BAG OF TRICKS - Quality Software SUPER DISK COPY - Sensible Software TASC - Microsoft THE EXPEDITER - On Line Systems THE DOS MANUAL - Apple Computer Corporation APPLE II REFERENCE MANUAL - Apple Computer Corporation WHAT'S WHERE IN THE APPLE - William F. Luebbert SOFTALK magazine NIBBLE magazine If you are familiar with the above manuals, software, and periodicals you ar e well on your way to locking programs. Also you will need use of one of the nib ble copiers on the market such as, LOCKSMITH, NIBBLES AWAY, or CLONE. CLONE is my choice because it is very fast compared to the others. LOCKING TECHNIQUES: MESS UP DOS Change some or all of the DOS commands. This in itself may be enough to prot ect your programs. Go a little further. Bury some control characters in the cata log. (control chrs. don't print usually). Change "CATALOG" to "LIST" and the Bas ic command "List " becomes unusable. Try it, you can't "list" a program in memory. Duplicate DOS commands are great. Only the first one encountered will work. Confuse the user by changing the disk error messages. For example do the following: 1) Change the SAVE command to STORE 2) Change the READ command to SAVE 3) Change the "NOT DIRECT COMMAND" error message to "NOT COPYABLE" Now when anyone tries to load and save your program you get the "NOT COPYABLE" error message because he used the wrong command! *** EXPERIMENT *** Now the following can be done to any disk you want. We will move the catalog track from track $11 to track $5, just for convenience mind you. 1) Boot your favorite 3.3 system master to load DOS 2) Placeyour DOS BOSS disk in the drive and type:LOAD DOS BOSS (return) 3) Type: Poke 44033,5 (return) 4) Place a blank disk into the disk drive and close the door. (something your parents keep telling you to do.) 5) Type: RUN (return) 6) Change a few commands...any one you want! 7) Before you leave DOS BOSS, change the disk volume heading to" SYNTAX ERROR" ... Don't forget the ctrl-G at the end! 8) Exit the DOS BOSS program. 9) Type: NEW (return) <--(by now you should remember) 10) Type: INIT HELLO 11) Wait a minute or so and pull the disk out of the drive. 12) Boot your system master again and try to catalog the disk you've just init iallized. If you have not noticed by now 44033 is the memory location that holds the cata log track number. Type: PRINT PEEK(44033), and you will see that DOS is looking at track 17 to find the catalog. Now if one were rather clever you would use som ething like SUPE R DISK COPY to copy the catalog track from another disk onto your modified disk . Also it will be necessary to change VTOC so that you do not overwrite real fil es on the disk. VTOC is normally located on track $11, sector $00. However the V TOC to fix on yo ur modified disk i ** T0 SYNC: 18=20 19=00 40=20 44=DD 45=AD 46=DA 72=00 73=00 77=00 78=00 79=12 7C=00 T1.5-TB.5 SYNC TD-T20 SYNC BORG ** T0: 18=20 19=00 40=20 4D=00 4E=00 52=00 53=00 54=12 57=00 72=00 73=00 77=00 78=00 79=12 7C=00 44=DD 45=AD 46=DA T1.5-TC.5 SYNC TD-T20 SYNC BPI BUSINESS ACCTING SYSTEM (4 DISKS) (REVISED 10-26) T0-T22: 19=00 21=02 58=19 59=06 5A=1A 5B=FF BD=44 BE=E6 BF=45 C0=FF C1=40 C2=01 C4=44 program RUN when any command is issued. POKE 1010,102: POKE 1011,213: POKE 1012,112 -- Makes RESET run the program in m emory. POKE 2049,1 -- Makes the first program line list repeately. Well by this time you should be bored stiff or really into learning copy pro tection. If the latter is the case continue to read, if the former, re-boot the system and fire up your favorite game. Now we shall take on the heavier ways to protect. If you were reading carefu lly to this point, you now should know how to change your DOS commands and chang e the catalog track. Also if you were experimenting you should have a few other tricks under you r belt. So, if you're having trouble at this point it would be advised to start at the beginning! In this section we will discuss the heavier ways of protection. CHECKSUM ALTERATION: In each sector on the disk is a byte which is the Checksum. This byte is the last byte to be written into a sector. The value of this byte varies with the a mount of information stored in that sector. Normal Apple DOS reads in the inform ation on the sec tor, and then counts the bytes it has read. It then compares this number to the checksum, if they are equal it continues to read the next sector. If it is not equal DOS has made an error and tries to read it again. After three tries it sto ps and gives the user an error message. In order to change the checksum we must change the byte should also be noted at this time, that your standard 3.3 DOS will no longer re ad this sector. Now in order to read this sector, we must disable the Checksum routine in DOS. To do this from the keyboard type the following: 1) CALL-151 2) B942:18 REM 3.3 DOS or B963:18 REM 3.2 DOS This changes a "set carry" instruction to a "clear carry" instruction. 3) 3D0G Now you're back in Basic. I hav'nt found a way to INIT a disk with this changed DOS yet, but by using DAK IN 5 PROGRAMMERS AIDS you can change DOS directly on your disk with the Patcher. The data to be zapped resides on track 0, sector 3. Byte $42 change $38 to $18 REM 3.3 DOS Byte $63 change $38 to $18 REM 3.2 DOS $D6, VECTOR: The D6 memory location in the Apple can set from Applesoft by typing POKE 21 4,255; OR from assembly by: LDA #$FF STA D6 This is where the Applesoft Run pointer resides. By putting a number larger tha n 128 in this location Applesoft equates a carriage return with the Applesoft RU N command. Once set, all user commands cause the program in memory to be execute d. LOADER DOS: Loader DOS is the minimal DOS that can be utilized in the Apple. It consists of nothing more than RWTS and a table of track and sector numbers that are to b e read in. Loader DOS has no DOS commands, as its only function is to load a pro gram, and start running it. If you're interested in this consult the DOS manual. The manual exp lains how to write the look-up table and how to utilize RWTS directly. HALF-TRACKING: half- tracking is utilizing the tracks between the normal tracks on the disk . This is possible because the disk drive is actually capable of writing to seve nty tracks, as that is the number of stepped positions the read/write head has. However one cann ot use these half tracks to double the amount of information stored on the disk due to hardware constraints in the Apple drive unit. In order to use half track s the adjacent full tracks must not be written to because of the high risk of ov erwriting or des troying information on the half track. It is only possible to write to half tra cks with assembly because the programmer must toggle the soft stepper switch onl y once and then access RWTS directly. DOS HOOK: In order to use a DOS HOOK one has to first write their own RWTS portion of DOS. Then write or modify the DOS boot routines to supply RWTS with a track and sector number and read that sector. This information is taken as data for RWTS a nd the next read . A program that utilizes the hook very effectively is MASTERTYPE from Lightning Software. PROGRAM LOCK: This is no more than a combination lock that is built into the program. To e ffectively use it, it is necessary to modify the boot routine in DOS. This is done by moving the PROM boot routine down into RAM where we can change it to stop after the first bootstrap routine is loaded. This is done by typing: 1) CALL-151 2) 9600


E-Mail Fredric L. Rice / The Skeptic Tank