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Added dBASE III copy-protection notes

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Jeff Parsons 2017-08-11 13:28:54 -07:00 • committed by Jeff Parsons
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_posts/2017-08-11-dbase-iii-copy-protection-revisited.md Normal file
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@ -0,0 +1,106 @@
---
layout: post
title: dBASE III Copy Protection Revisited
date: 2017-08-11 10:00:00
permalink: /blog/2017/08/11/
---
One of the earliest tasks I remember tackling on an IBM PC was a basically a favor for my father-in-law, Tom Estelita.
In 1984, he had purchased a copy of dBASE III and had become frustrated by its copy-protection. The previous version,
dBASE II, had no such protection, which probably added to his frustration. At the time, he was running his own tiny
software company, Radix 2 Software, and he certainly wasn't interested in redistributing dBASE III -- he just wanted to
be able to back-up his software and switch between a handful of machines without the hassle or worry of relying on a
single fragile copy-protected diskette.
At that time, my day job was writing PDP-11 application software, but I really wanted to learn more about the IBM PC,
and I had done work for Tom in the past (writing BASIC accounting software on CP/M-based machines), so he made me a
deal: he would loan me a floppy-based IBM PC and some IBM reference manuals, in exchange for attempting to crack dBASE
III's copy-protection.
I have no recollection of how feasible I thought this challenge was, but I'm sure I jumped at the opportunity.
Perhaps my thinking was that, after all, it's just software, so how hard could it be. In any case, I apparently took
the challenge very seriously, because I also made a lot of notes.
I recently found [those notes](/docs/personal/#dbase-iii-copy-protection), along with copies of the
[dBASE III disks](/disks/pcx86/apps/other/dbase3/1.0/) used. Unfortunately, all they contained was my *patched*
(unlocked) version of `DBASE.EXE`, and for the sake of a complete archive, I wanted the *unpatched* (locked) version as
well. Fortunately, my patching notes also show all the original bytes, so I reproduced the original file by reversing
the patching process, using PCjs:
Loading /disks/pcx86/apps/other/dbase3/1.0/DBIII-100-UNLOCKED.json.......
FDC: Mounted diskette "dBASE III 1.0 (Unlocked)" in drive A
A>dir
Volume in drive A has no label
Directory of A:\
DBASE EXE 112720 9-28-84 3:46p
DBASE OVL 147456 6-26-84 5:36p
HELP DBS 53760 6-26-84 5:36p
ASSIST HLP 15223 6-26-84 5:37p
READ ME 4224 6-26-84 5:37p
CONFIG SYS 22 6-26-84 5:37p
6 File(s) 15360 bytes free
A>ren dbase.exe dbase.tmp
A>b:debug dbase.tmp
-d 5f4 l4
08FF:05F4 25 39 4F 45 %9OE
-e 5f4
08FF:05F4 25. 39.e3 4F.c4 45.eb
-d a44
08FF:0A44 2D 26 AB 36-38 06 9C 17 1A 54 A5 4B -&+68....T%K
08FF:0A50 E8 41 4C E0 AF 68 0B 07-6E 07 80 16 1B B6 BF B7 hAL`/h..n....6?7
08FF:0A60 4C 6B C2 39 26 DC 97 BF-3B CE C0 EB 4F BB B3 C2 LkB9&\.?;N@kO;3B
08FF:0A70 27 A6 90 75 F4 AF 68 93-DF 62 43 CD B7 65 AD 34 '&.ut/h._bCM7e-4
08FF:0A80 11 B0 85 93 29 A2 9B A4-42 74 A6 84 24 7C 17 4C .0..)".$Bt&.$|.L
08FF:0A90 7B 5E F9 2C 66 0E 4E 27-B4 2F 50 4E 9C 76 CE D6 {^y,f.N'4/PN.vNV
08FF:0AA0 DB 51 21 D1 2C 4B 3B 73-48 EE 8E 6A 9C D7 E2 4F [Q!Q,K;sHn.j.WbO
08FF:0AB0 FA B6 10 24 28 A0 45 C8-50 36 9A 5E 9F C4 A1 EC z6.$( EHP6.^.D!l
08FF:0AC0 A2 51 AA B8 "Q*8
-e a44
08FF:0A44 2D.b0 26.5e AB.e6 36.af
08FF:0A48 38.1e 06.f1 9C.41 17.31 1A.73 54.59 A5.c1 4B.a4
08FF:0A50 E8.0e 41.cd 4C.63 E0.fe AF.c1 68.39 0B.0b 07.62
08FF:0A58 6E.60 07.93 80.be 16.cf 1B.08 B6.f8 BF.4e B7.56
08FF:0A60 4C.53 6B.d3 C2.5d 39.4f 26.a3 DC.9a 97.ae BF.14
08FF:0A68 3B.c4 CE.7b C0.dc EB.e4 4F.ee BB.45 B3.f9 C2.ab
08FF:0A70 27.3f A6.15 90.56 75.3d F4.5b AF.a3 68.a1 93.20
08FF:0A78 DF.ad 62.98 43.be CD.02 B7.c8 65.63 AD.df 34.c3
08FF:0A80 11.e0 B0.2f 85.26 93.af 29.31 A2.29 9B.40 A4.4f
08FF:0A88 42.86 74.98 A6.90 84.fc 24.d6 7C.76 17.e3 4C.e5
08FF:0A90 7B.f1 5E.61 F9.08 2C.8a 66.20 0E.f7 4E.37 27.64
08FF:0A98 B4.4f 2F.e2
-w
Writing 1B850 bytes
-q
A>ren dbase.tmp dbase.exe
A>dir
Volume in drive A has no label
Directory of A:\
DBASE EXE 112720 8-11-17 9:51a
DBASE OVL 147456 6-26-84 5:36p
HELP DBS 53760 6-26-84 5:36p
ASSIST HLP 15223 6-26-84 5:37p
READ ME 4224 6-26-84 5:37p
CONFIG SYS 22 6-26-84 5:37p
6 File(s) 15360 bytes free
saving diskette /disks/pcx86/apps/other/dbase3/1.0/DBIII-100-UNLOCKED.json...
I haven't examined this patch again (yet), but I will admit that it seems rather lengthy. Usually one strives for
a very small, surgically precise patch that's more on the order of 3 or 4 bytes, but we have to remember that I wasn't
very familiar with either the IBM PC or the 8088 instruction set at this point -- this was also a learning exercise.
And who knows, maybe Vault Corporation (the company that Ashton-Tate used to provide the copy-protection logic for
dBASE III) wrote such sophisticated code that it was impossible to defeat so simply. However, experience suggests
that's unlikely.
*[@jeffpar](http://twitter.com/jeffpar)*
*Aug 11, 2017*

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disks/pcx86/apps/other/dbase3/1.0/DBIII-100-LOCKED.json Normal file
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0
disks/pcx86/apps/other/dbase3/1.0/DBIII-100-UNLOCKED.json → disks/pcx86/apps/other/dbase3/1.0/DBIII-100-PATCHED.json
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45
disks/pcx86/apps/other/dbase3/1.0/README.md
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@ -7,30 +7,38 @@ permalink: /disks/pcx86/apps/other/dbase3/1.0/
dBASE III v1.0
--------------
The first two PCjs disks shown below:
Two of the PCjs disks shown below:
- [dBASE III 1.0 (Unlocked)](#directory-of-dbase-iii-10-unlocked)
- [dBASE III 1.0 (Patched)](#directory-of-dbase-iii-10-patched)
- [dBASE III 1.0 (Samples)](#directory-of-dbase-iii-10-samples)
are from our private collection and should be exact copies of the original dBASE III v1.0 distribution disks, with
the exception of `DBASE.EXE`, which was patched to eliminate copy-protection checks. If possible, details on that
patch will be provided at a later date.
are from our private collection and should be exact copies of the original dBASE III v1.0 distribution disks, with the
exception of `DBASE.EXE`, which was patched to eliminate copy-protection checks. Details of that patch are available
in our collection of [Personal Documents of Dubious Historical Interest](/docs/personal/#dbase-iii-copy-protection),
along with this [blog post](/blog/2017/08/11/).
The other disks:
Also, for completeness, the original `DBASE.EXE` has been recreated by "unpatching" it and saving it on the
[Locked](#directory-of-dbase-iii-10-locked) disk image. However, we don't have the original distribution disk, which
would include additional copy-protection characteristics, so running the original (locked) version of `DBASE.EXE` will
immediately fail with:
Unauthorized Duplicate
Another variation of the dBASE III disks come from the [WinWorld](https://winworldpc.com/product/dbase/iii-v10) archive:
- [dBASE III 1.0 (Disk 1)](#directory-of-dbase-iii-10-disk-1)
- [dBASE III 1.0 (Disk 2)](#directory-of-dbase-iii-10-disk-2)
come from [WinWorld](https://winworldpc.com/product/dbase/iii-v10). With the exception of `DBASE.EXE`, the files on
the "Disk 1" image match the files on our "Unlocked" disk; the newer dates probably only reflect when Ashton-Tate and/or
Vault Corporation updated the copy-protection code in `DBASE.EXE`. However, the "Disk 2" image contains more files
than our "Samples" disk, and WinWorld's README admits that:
and, with the exception of `DBASE.EXE`, the files on [Disk 1](#directory-of-dbase-iii-10-disk-1) match the files on our
[Patched](#directory-of-dbase-iii-10-patched) disk; the newer dates probably just reflect an update by Vault Corporation
to the copy-protection code in `DBASE.EXE`. However, [Disk 2](#directory-of-dbase-iii-10-disk-2) contains more files
than our [Samples](#directory-of-dbase-iii-10-samples) disk, and WinWorld's README admits that:
Some of the sample programs have been run/changed.
so overall, the PCjs disks may be more authentic.
so overall, the disks from our private collection may be more authentic.
### Directory of dBASE III 1.0 (Unlocked)
### Directory of dBASE III 1.0 (Patched)
Volume in drive A has no label
Directory of A:\
@ -105,6 +113,19 @@ so overall, the PCjs disks may be more authentic.
PAYROLL PRG 13056 6-15-84 4:50p
55 File(s) 75776 bytes free
### Directory of dBASE III 1.0 (Locked)
Volume in drive A has no label
Directory of A:\
DBASE EXE 112720 8-11-17 9:51a
DBASE OVL 147456 6-26-84 5:36p
HELP DBS 53760 6-26-84 5:36p
ASSIST HLP 15223 6-26-84 5:37p
READ ME 4224 6-26-84 5:37p
CONFIG SYS 22 6-26-84 5:37p
6 File(s) 15360 bytes free
### Directory of dBASE III 1.0 (Disk 1)
Volume in drive A has no label

15
disks/pcx86/apps/other/dbase3/1.0/manifest.xml
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@ -95,8 +95,17 @@
<file size="1024" time="1984-11-06 03:12:54" attr="0x20">WHO.NDX</file>
<file size="1024" time="1984-11-13 08:23:36" attr="0x20">ZIP.NDX</file>
</disk>
<disk id="disk03" size="368640" chs="40:2:9" img="archive/DBIII-100-UNLOCKED.img" href="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-UNLOCKED.json" md5="c291c4175ee9f5b983a5bb0168421a92" md5json="3d7bc6010f165cb5c41592c9c05e15f2">
<name>dBASE III 1.0 (Unlocked)</name>
<disk id="disk03" size="368640" chs="40:2:9" img="archive/DBIII-100-LOCKED.img" href="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-LOCKED.json" md5="e7c73904362b5298b49a67402d2b00a5" md5json="7940716852d3d71ab64d68e1ac846960">
<name>dBASE III 1.0 (Locked)</name>
<file size="15223" time="1984-06-26 17:37:02" attr="0x20">ASSIST.HLP</file>
<file size="22" time="1984-06-26 17:37:08" attr="0x20">CONFIG.SYS</file>
<file size="112720" time="2017-08-11 09:51:22" attr="0x20">DBASE.EXE</file>
<file size="147456" time="1984-06-26 17:36:48" attr="0x20">DBASE.OVL</file>
<file size="53760" time="1984-06-26 17:36:58" attr="0x20">HELP.DBS</file>
<file size="4224" time="1984-06-26 17:37:06" attr="0x20">READ.ME</file>
</disk>
<disk id="disk04" size="368640" chs="40:2:9" img="archive/DBIII-100-PATCHED.img" href="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-PATCHED.json" md5="c291c4175ee9f5b983a5bb0168421a92" md5json="3d7bc6010f165cb5c41592c9c05e15f2">
<name>dBASE III 1.0 (Patched)</name>
<file size="15223" time="1984-06-26 17:37:02" attr="0x20">ASSIST.HLP</file>
<file size="22" time="1984-06-26 17:37:08" attr="0x20">CONFIG.SYS</file>
<file size="112720" time="1984-09-28 15:46:34" attr="0x20">DBASE.EXE</file>
@ -104,7 +113,7 @@
<file size="53760" time="1984-06-26 17:36:58" attr="0x20">HELP.DBS</file>
<file size="4224" time="1984-06-26 17:37:06" attr="0x20">READ.ME</file>
</disk>
<disk id="disk04" size="368640" chs="40:2:9" img="archive/DBIII-100-SAMPLES.img" href="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-SAMPLES.json" md5="919393aa18749389e54ebbb07c83c424" md5json="e2ff2cead7607519001d4357bb9a8439">
<disk id="disk05" size="368640" chs="40:2:9" img="archive/DBIII-100-SAMPLES.img" href="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-SAMPLES.json" md5="919393aa18749389e54ebbb07c83c424" md5json="e2ff2cead7607519001d4357bb9a8439">
<name>dBASE III 1.0 (Samples)</name>
<file size="1408" time="1984-04-30 09:08:58" attr="0x20">ACCOUNTS.PRG</file>
<file size="1280" time="1984-06-15 15:26:20" attr="0x20">BIG.PRG</file>

3
disks/pcx86/compiled/library.xml
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@ -384,7 +384,8 @@
<disk path="/disks/pcx86/apps/other/dbase2/2.4/DBII-240-SCED.json">dBASE II 2.4 (EDITOR)</disk>
<disk path="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-DISK1.json">dBASE III 1.0 (Disk 1)</disk>
<disk path="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-DISK2.json">dBASE III 1.0 (Disk 2)</disk>
<disk path="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-UNLOCKED.json">dBASE III 1.0 (Unlocked)</disk>
<disk path="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-LOCKED.json">dBASE III 1.0 (Locked)</disk>
<disk path="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-PATCHED.json">dBASE III 1.0 (Patched)</disk>
<disk path="/disks/pcx86/apps/other/dbase3/1.0/DBIII-100-SAMPLES.json">dBASE III 1.0 (Samples)</disk>
<disk path="/disks/pcx86/apps/other/omniview/4.30/OMNIVIEW386-430.json">Omniview 386 4.30</disk>
<disk path="/disks/pcx86/apps/other/sc2/1.00/SC2_V100.json">SuperCalc2 1.00</disk>

4
docs/personal/README.md
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@ -8,7 +8,7 @@ Personal Documents of Dubious Historical Interest
-------------------------------------------------
I'm kicking off this new section of the site with a couple of documents I created in 1984, detailing one of my early
adventures in PC debugging: decoding and removing [dBASE III Copy-Protection](#dbase-iii-copy-protection).
adventures in PC debugging: decoding and disabling [dBASE III Copy-Protection](#dbase-iii-copy-protection).
---
@ -17,7 +17,7 @@ adventures in PC debugging: decoding and removing [dBASE III Copy-Protection](#d
* [dBASE III Debugging Notes](/docs/personal/1984-09-16--DBASE_III_DEBUG.pdf)
* [dBASE III Patching Procedure](/docs/personal/1984-09-25--DBASE_III_PATCH.pdf)
NOTE: Copies of the [dBASE III](/disks/pcx86/apps/other/dbase3/) disks can be found in our [IBM PC Disk Library](/disks/pcx86/).
NOTE: Copies of the [dBASE III](/disks/pcx86/apps/other/dbase3/1.0/) disks can be found in our [IBM PC Disk Library](/disks/pcx86/).
*[@jeffpar](http://twitter.com/jeffpar)*
*Last Update: Aug 11, 2017*