Wordlock

Wordlock
by Andy A. Lee

If you have $10 million at home, where do you think is a safer place for it? The heavy-duty safe in your study or the center of your driveway, where everyone can see it?

The safe, of course, is the better place. The programs on your disks are like money on your driveway. You know most people who come by and see the money would take it if you're not around. This applies to your programs too! If you leave your disks lying around, sooner or later your programs will be copied without your authorization.
Wordlock is a binary program that will stop all that. Using a password of up to 14 characters, it assures you that no one else will have access to your programs.

The programs on your
disks are like money on
your driveway. You
know most people who
come by and see the
money would take it
if you're not around.

How does it do that?

First of all, let's take a look at the programs on your disks. Atari programs are made up of sequences of bytes, or numbers between 0 and 255. When you're saving a program, the computer puts the program directly from memory to the disk. So when you're loading it, the computer just copies the sequences of bytes back to memory.

The user will be asked
to enter a password
whenever the computer
is going to save or load
a program. You can
enter up to 14
characters as your
password.

   Let's play a game: Assume we have a number, 2534, and we want to remember this number by writing it down on paper. But we don't want to let others know what this number is. So we add one to every digit of 2534. After we do that, we will have a new number, 3645. We can now write that down on a piece of paper and nobody will guess the number is actually 2534. When we come back tomorrow to read the number, all we have to do is subtract one from every digit of 3645 to get the original number, 2534.
   So much for fun-let's get back to our computer. We know the programs are made up of sequences of bytes, or numbers between 0 and 255, in the memory of our computer. The computer saves the programs to disk exactly as they are in memory. And the computer loads it back to memory exactly as they are on disk. If we add one to every byte as it goes to the disk, we will have a sort of code.
   If we want to restore the program, we should subtract one from every byte, and then put the result of the subtraction in memory. If we don't subtract one (copy the bytes exactly as they are on disk), the program will not be restored, because every byte will be off by one. See how it works?
   Similar techniques are used in Wordlock, though they are much more complicated than just subtraction or addition. Every character of your password or passphrase is used in the coding process. So if you misspell the word by one letter or leave a letter out, you will not be able to load the program.
   Type in Listing 1 using the M/L Editor, and name the resultant file AUTORUN.SYS.
   To use Wordlock, you need to load the binary program as soon as possible after the boot process. This means if you are using a DOS that recognizes AUTORUN.SYS, you should name Wordlock AUTORUN.SYS so it will be loaded right after DOS. Such DOSs include DOS 2, DOS 2.5, DOS 3, SpartaDOS 23C.b, etc. If you are using a DOS that gives you control after the system is booted, please refer to your user's manual. It should tell you how to load a binary file. For example, OS/A + and SPARTADOS 1.1 give you a "Dl:" prompt after the boot process. You'll only need to type in "WORDLOCK" and press RETURN if you name the Wordlock file WORDLOCK.COM.
   Once Wordlock is loaded, it will be present until you turn the computer off. The reset key does nothing to it.

Password entering

The user will be asked to enter a password whenever the computer is going to save or load a program. You can enter up to 14 characters as your password. Carefully check your password before you press RETURN. If the program you're loading or saving doesn't need a password, all you have to do when it asks for the password is press RETURN. This tells Wordlock to save or load the program as it is in memory or on disk. You need to do this to load old programs. Here's how to assign a password to your old programs:

Load the program.
When Wordlock asks for the password, press RETURN.
Save the program.
Wordlock will ask for a password. Enter your password for this program.
Remember the password!

Last word

Since it's impossible to restore your programs if you don't have the password, use only one or two passwords on all your programs-or write your passwords down some place. It's also a good idea to use at least four characters in your password.

Since it's impossible to
restore your programs
if you don't have the
password, use only one
or two passwords on all
your programs-or
write your passwords
down someplace.

   Listing 2 is the assembly source code for Wordlock, written using MAC/65. Wordlock locates itself at MEMLO, the first available memory in RAM for users, so it should work with all DOSs and all 8-bit Atari languages.

Andy Lee is 18 years old and attends Concord High School in Elkhart, Indiana. He moved to the U.S. from Taiwan in the summer of '82. He has been programming Atari computers for over two years, and also runs a BBS called Green Alley Bulletin Board System.

LISTING 1: M/L EDITOR DATA

1000 DATA 255,255,0,64,78,66,32,255,25
5,162,0,160,0,142,231,2,6391
1010 DATA 140,232,2,162,0,160,0,134,12
,132,13,169,87,141,253,3,4847
1020 DATA 96,142,255,3,32,255,255,8,19
2,1,240,2,40,96,136,174,6806
1030 DATA 255,3,152,157,14,4,189,74,3,
201,4,240,4,201,8,208,5659
1040 DATA 85,169,11,141,254,3,172,254,
3,185,254,64,32,235,64,206,9985
1050 DATA 254,3,208,242,32,246,64,160,
14,217,9,65,240,246,136,208,1373
1060 DATA 248,201,126,208,13,172,254,3
,240,234,32,235,64,206,254,3,1065
1070 DATA 16,226,201,155,240,24,168,17
3,254,3,201,14,240,214,13,255,1751
1080 DATA 3,170,152,157,0,4,32,235,64,
238,254,3,16,198,32,235,7641
1090 DATA 64,172,254,3,208,8,152,174,2
55,3,157,0,4,200,174,255,9410
1100 DATA 3,152,157,15,4,160,1,174,255
,3,40,96,142,255,3,32,4207
1110 DATA 255,255,8,140,254,3,174,255,
3,32,193,64,172,254,3,40,6720
1120 DATA 96,32,193,64,76,255,255,72,1
42,255,3,189,14,4,13,255,7028
1130 DATA 3,168,254,14,4,189,14,4,221,
15,4,208,5,169,0,157,3193
1140 DATA 14,4,104,240,8,217,0,4,240,3
,89,0,4,174,255,3,3338
1150 DATA 96,168,173,7,228,72,173,6,22
8,72,152,96,173,37,228,72,7895
1160 DATA 173,36,228,72,96,32,58,32,10
0,114,111,119,115,115,97,80,4240
1170 DATA 27,28,29,30,31,125,127,156,1
57,158,159,253,254,255,166,212,5034
1180 DATA 164,213,142,48,66,140,50,66,
174,42,3,172,43,3,134,212,4522
1190 DATA 132,213,173,253,3,201,87,208
,3,76,47,66,166,12,164,13,3863
1200 DATA 142,1,64,140,2,64,174,231,2,
172,232,2,134,12,132,13,3968
1210 DATA 142,14,64,140,16,64,24,173,2
31,2,105,24,141,4,64,173,3307
1220 DATA 232,2,105,1,141,6,64,160,0,2
4,177,212,105,1,141,31,2965
1230 DATA 64,200,177,212,105,0,141,32,
64,160,4,24,177,212,105,1,4209
1240 DATA 141,170,64,200,177,212,105,0
,141,171,64,200,24,177,212,105,9338
1250 DATA 1,141,191,64,200,177,212,105
,0,141,192,64,160,0,24,169,6182
1260 DATA 26,109,231,2,145,212,200,169
,0,109,232,2,145,212,160,4,7937
1270 DATA 24,169,165,109,231,2,145,212
,200,169,0,109,232,2,145,212,9850
1280 DATA 200,24,169,186,109,231,2,145
,212,200,169,0,109,232,2,145,8666
1290 DATA 212,162,17,189,61,66,133,213
,202,189,61,66,133,212,160,1,8253
1300 DATA 56,177,212,233,0,145,212,200
,177,212,233,64,145,212,136,24,1553
1310 DATA 177,212,109,231,2,145,212,20
0,177,212,109,232,2,145,212,202,3290
1320 DATA 16,209,174,231,2,172,232,2,1
34,212,132,213,160,0,185,0,8071
1330 DATA 64,145,212,200,208,248,230,2
13,160,23,185,0,65,145,212,136,898
1340 DATA 192,255,208,246,24,173,231,2
,105,24,141,231,2,173,232,2,7909
1350 DATA 105,1,141,232,2,162,0,160,0,
134,212,132,213,169,87,141,9022
1360 DATA 253,3,96,70,64,100,64,128,64
,136,64,78,64,67,64,83,2213
1370 DATA 64,179,64,187,64,226,2,227,2
,24,65,0,0,0,0,0,7211

LISTING 2: ASSEMBLY

10       .OPT NO LIST
20 ; *************************
30 ; *                       *
40 ; *        WORD-LOCK *
50 ; *                       *
51 ; *       April, 1986    *
52 ; *                       *
60 ; * by Andy A. Lee *
70 ; *                     *
88 ; *************************
90 ;
0100 INDEX = $03FE
0110 CHN16 = $03FF
0120 BADS = $0E
0130 MAXIM = $0E
0140 DELETE = $7E
0150 RETURN = $90
0160 DOSINI = $0C
0170 ICAX1 = $034A
0180 MEMLO = $82E7
0190 READ = $04
0200 WRITE = $08
0210 OK =   $01
0220 PASS = $0400
0230 CNTR = PASS+14
0240 LENS = PASS+15
0250 *= $4000
0260 ;
0270 ; Rest Init...
0280 ; ------------
0290 ;
0300 TODOS JSR $FFFF
0310 MLLSB LDX #$00
0320 MLMSB LDY #$00
0330    STX MEMLO
0340   STY MEMLO+1
0350 TDLSB LDX #$00
0360 TDMSB LDY #$00
0370   STX DOSINI
0380   STY DOSINI+1
0390    LDA #'W
0400   STA $03FD
0410     RTS
0420 ;
0430 ; Open vector
0440 ; -----------
0450 ;
0460 OPEN STX CHN16
0470 DOPM JSR $FFFF ; Open the file
0480   PHP    ; Save status
0490    CPY #OK    ; Process okay?
0500    BEQ OURJOB ; OK! Our turn!
0510   PLP ; Error code
0520    RTS    ; Return
0530 ;
0540 ; Our works
0550 ; ---------
0560 ;
0570 OURJOB DEY
0580    LDX CHN16
0590    TYA ; reset counter
0600   STA CHTR,X ; to zero
0610 LDA ICAXI,X ; Is this...
0620 CMP #READ   ; read a file?
0630   BEQ CONT    ; Continue if so
0640    CMP #WRITE ; write a file?
0650    BNE NOPASSWORD ; nopassword
0660 ; if it isn't read or write...
0670 ;
0680 ; PRINT "Password : "
0690 ; ------------------------
0700 ;
0710 CONT LDA #11    ; 11 characters
0720    STA INDEX
0730 PRLOOP
0740    LDY INDEX ; Load index
0750 M1 LDA MSG-1,Y ; A charater
0760 S1 JSR SCREEN ; Print it
0770    DEC INDEX   ; Next character
0780   BNE PRLOOP ; Done?
0790 ;
0800 ; Input the password.
0810 ; -------------------
0820 ;
0830 INLOOP
0840 I1 JSR INPUT   ; A keystroke
8850   LDY UBADS
0860 CHLOOP
0870 B1 CMP BADIN-1,Y ; Compare with
0880    BEQ INLOOP ; unusable
0890 DEY ; input table.
0900    BNE CHLOOP
0910   CMP #DELETE ; Delete backs?
0920    BNE CH2    ; If not...
0930    LDY INDEX   ; Check index
8940    BEQ INLOOP ; No input yet!
0950 S2 JSR SCREEN ; Delete letter
0960    DEC INDEX   ; = INDEX - 1
0970    BPL INLOOP ; Next key
0980 CH2 CMP #RETURN ; RETURN key?
0990 BEQ STOPIN ; If so, stop
1000    TAY    ; Y reg. = A
1010    LDA INDEX   ; Too many?
1020   CMP #MAXIN
1030    BEQ INLOOP ; Yes!!!
1040    ORA CHN16   ; Store
1050     TAX
1060     TYA
1070   STA PASS,X
1080 S3 JSR SCREEN ; Print it too.
1090   INC INDEX   ; = INDEX + 1
1100    BPL INLOOP ; Next key
1110 STOPIN
1120 S4 JSR SCREEN ; Print the <CR)
1130     LDY INDEX   ; PASSWORD?
1140     BNE SVLEN   ; Yes, go on ...
1150 NOPASSWORD
1160    TYA         ; Y reg. = 0
1170 LDX CHN16   ; Clean password
1180 STA PASS,X
1190 INY       ; Length = 1
1200 SVLEN LDX CHN16 ; Save length
1210 TYA
1220    STA LEMS,X
1230    LDY #OK    ; No error flag
1240    LDX CHN16
1250     PLP
1260   RTS    ; All done.
1270 ;
1280 ; Get vector
1290 ; ----------
1300 ;
1310 GET STX CHN16
1320 DGET JSR $FFFF ; Get a byte
1330   PHP     ; Save status
1340    STY INDEX   ; Save Y reg.
1350    LDX CHN16
1360 C1 JSR CODE    ; Decode byte
1370   LDY INDEX   ; Restore Y reg.
1380   PLP     ; Reload status
1390   RTS   ; Done!
1400 ;
1410 ; Put vector
1420 ; ----------
1430 ;
1440 PUT
1450 C2 JSR CODE    ; Code the byte
1460 DPUT JMP $FFFF ; Output to disk
1470 CODE PHA
1480   STX CHN16   ; Save channel #
1490    LDA CHTR,X ; calculate the
1500    ORA CHN16   ; byte to FOR
1510    TAY    ; with...
1520    INC CHTR,X ; Reset counter
1530   LDA CNTR,X ; Set back to
1540   CMP LENS,X ;   zero?
1550    BNE NOTNOW
1560    LDA #$00    ; set to zero
1570   STA CHTR,X
1580 NOTNOW PLA      ; Load the byte.
1590    BEQ EXIT    ; ZERO? bypass!
1600    CMP PASS,Y ; = CODE BYTE?
1610    BEQ EXIT    ; Bypass
1620    EOR PASS,Y ; Coding...
1630 EXIT LDX CHN16 ; All done
1640   RTS   ; Bye-bye!
1650 ;
1660 ; Screen - print a character
1670 ;      on screen.
1680 ;
1690 SCREEN
1700   TAY    ; A = character
1710 LDA $E407   ; location of
1720 PHA   ; PRINT routine
1730 LDA $E406   ; in OS
1740 PHA
1750 TYA   ; restore A
1760   RTS   ; goto routine
1770 ;
1780 ; Input - input a keystroke
1790 ;
1800 INPUT
1810    LDA $E425   ; location of
1820    PHA    ; INPUT routine
1830   LDA $E424   ; in OS
1840     PHA
1850 RTS   ; goto routine
1860 MSG
1870     .BYTE " : drowssaP"
1880 ;
1890 ; Following characters are not
1900 ; usable for password.
1910 ;
1920 BADIN
1930    .BYTE 27,28,29,38,31,125,127
1940     .BYTE 156,157,158,159,253
1950     .BYTE 254,255
1960 ;
1970 ; Install WORDLOCK
1980 ; ----------------
1990 ;
2000 INIT LDX $D4
2010 LDY $D5
2020   STX X+1
2030    STY Y+1
2040    LDX $032A   ; Get address
2050   LDY $032B   ; of "D" vectors
2060   STR $D4   ; table
2070   STY $D5
2080 ;
2090 ; We will see if WORDLOCK is
2100 ; already installed
2110 ;
2120 CHECK
2130 LDA $03FD
2140    CMP #'W
2150    BNE COPY
2160   JMP ERITINIT
2170 ;
2180 ; We now install WORDLOCK
2190 ;
2200 COPY
2210    LDX DOSINI
2220    LDY DOSINI+1
2230 STX TODOS+1
2240 STY TODOS+2
2250 LDX MENLO
2260   LDY MEMLO+1
2270 STX DOSINI
2280 STY DOSINI+1
2290 STX TDLSB+1
2300    STY TDMSB+1
2310    CLC   ; calculate new
2320    LDA MENLO   ; MENLO
2330 ADC # <INIT-$4000
2340 STA MLLSB+1
2350 LDA MEMLO+1
2360 ADC # >INIT-$4000
2370 STA MLMSB+1
2380    LDY #0      ; First, copy
2390    CLC    ; OPEN vector
2400 LDA ($D4),Y ; so we can use
2410 ADC #$01    ;    it ...
2420 STA DOPN+1
2430 INY
2440 LDA ($D4),Y
2450    ADC #$00
2460 STA DOPN+2
2470 LDY #4      ; Now the GET
2480 CLC   ; vetor too...
2490 LDA ($D4),Y
2500 ADC #$01
2510 STA DGET+1
2520 INY
2530    LDA ($D4),Y
2540    ADC #$00
2550 STA DGET+2
2560   INY    ; Last, PUT
2570 CLC   ; vector...
2580    LDA (SD4),Y
2590 ADC #$01
2600 STA DPUT+1
2610 INY
2620   LDA ($D4),Y
2630 ADC #$00
2640   STA DPUT+2
2650   LDY #0
2660    CLC      ; Insert My OPEN
2670 LDA # <OPEN-$4001 ; vector
2680    ADC MENLO
2690    STA ($D4),Y
2700     INY
2710    LDA # >OPEN-$4001
2720    ADC MEMLO+1
2730    STA ($D4),Y
2740    LDY #4    ; Insert My GET
2750 CLC ; vector
2760 LDA # <GET-$4001
2770   ADC MENLO
2780 STA ($D4),Y
2790     INY
2800 LDA # >GET-$4001
2810 ADC MEMLO+1
2820    STA ($D4),Y
2830    INY   ; Insert My PUT
2940 CLC    ; vector
2850 LDA # <PUT-$4001
2860    ADC MENLO
2870   STA ($D4),Y
2880     INY
2890 LDA # >PUT-$4001
2900 ADC MEMLO+1
2910    STA ($D4),Y
2920   LDX #17
2930 CAL LDA MOVETHESE,X
2940   STA $D5
2950 DEX
2960 LDA MOVETHESE,X
2970 STA $D4
2980    LDY #1
2990     SEC
3000 LDA ($D4),Y
3010    SBC # <4000
3020 STA ($D4),Y
3030     INY
3040    LDA ($D4),Y
3050 SBC # >$4000
3060   STA ($D4),Y
3070 DEY
3080     CLC
3090    LDA ($D4),Y
3100 ADC MENLO
3110 STA ($D4),Y
3120     INY
3130 LDA ($D4),Y
3140 ADC MEMLO+1
3150 STA ($D4),Y
3160     DEX
3170    BPL CAL
3180 LDX MENLO
3190 LDY MEMLO+1
3200    STX SD4
3210    STY $D5
3220    LDY #0
3230 MOVE LDA TODOS,Y
3240    STA ($D4),Y
3250     INY
3270    BNE MOVE
3271    INC $D5
3272    LDY # <INIT-$4001
3273 MOVE2 LDA TODOS+$0100,Y
3274    STA ($D4),Y
3275     DEY
3276    CPY #$FF
3277    BNE MOVE2
3280    CLC    ; calculate new
3290    LDA MENLO   ; MENLO
3300    ADC # <INIT-4000
3310    STA MENLO
3320    LDA MEMLO+1
3330    ADC # >INIT-$4000
3340    STA MEMLO+1
3350 ERITINIT
3360 R   LDX #$00
3370 Y   LDY #$00
3380    STR $D4
3390    STY $D5
3400 LDA #'W
3410 STA $03FD
3420     RTS
3430 MOVETHESE .WORD S1,S2,S3,S4
3440     .WORD I1,M1,B1,C1,C2
3450     *= $02E2
3460     .WORD INIT