
Old-School PC Copy Protection Schemes (2006) - erickhill
http://www.vintagecomputing.com/index.php/archives/174/old-school-copy-protection-schemes
======
Nr7
IMO Dungeon Master for the Atari ST & Amiga has the greatest copy protection
scheme ever created. It utilized (amongst a multitude of other things)
something called "fuzzy bits" that were bits which values were not set but
could be either "0" or "1" when read.

>If you copy your original Dungeon Master floppy disk using your favorite disk
copier, the copy will not have the fuzzy bits but normal bits instead. The
game can easily detect their presence by reading these bits several times: if
it gets random results, then it assumes the disk is original. If it gets
consistent results, it assumes the disk is a copy.

[http://dmweb.free.fr/?q=node/210](http://dmweb.free.fr/?q=node/210)

~~~
jonathankoren
This worked because the magnetic domains on the disk were larger than the r/w
head on drive, and due to play in the servo mechanism. It's the same reason
why the DOD creates the 7-pass rule for securely erasing disks. You could
simply read the disk multiple times and get slightly different results with
some statistical analysis and some cribs, you could at least partially
reconstruction the original data.

Today, magnetic disks have magnetic domains pretty much the same size as the
head, and the servos are much more accurate. One pass erasing is sufficient.
27-pass is just a waste of time.

Now for SSDs, you're just screwed.

~~~
legodt
Could you please elaborate on your SSD comment? I'm interested to hear more.

~~~
theandrewbailey
SSD wear leveling algorithms ensure that the entire disk is used evenly. Any
block on the drive can be literally anywhere in the storage medium, even more
so than with hard drives. Some SSDs have significantly more storage media than
they report (over-provisioning), again for wear leveling.

In theory, SSD erasing is solved by TCG OPAL functionality. All data written
to the disk medium is encrypted, whether or not it is taken advantage of by
the user. The key it uses cannot be retrieved or set by the user. Tell the
disk to change the key it uses and the entire device is unintelligible noise.

Some articles: [http://www.techrepublic.com/article/erasing-ssds-security-
is...](http://www.techrepublic.com/article/erasing-ssds-security-is-an-issue/)

[http://arstechnica.com/security/2011/03/ask-ars-how-can-i-
sa...](http://arstechnica.com/security/2011/03/ask-ars-how-can-i-safely-erase-
the-data-from-my-ssd-drive/)

~~~
flyinghamster
Shouldn't the ATA Secure Erase command take care of properly blanking an SSD?
(Assuming that its firmware can be trusted, of course.)

In practice, it's a bit more complicated, though - typically the BIOS (or is
the operating system?) locks out Secure Erase and you have to hot-remove the
drive and reconnect it before the drive will accept it.

~~~
bitwize
> Shouldn't the ATA Secure Erase command take care of properly blanking an
> SSD? (Assuming that its firmware can be trusted, of course.)

It does that -- by clobbering the hw encryption key.

------
camiller
Back in the Apple ][+ days there was a copy protection scheme that depended on
the spindle speed/timing of the old Apple ][ disk drive. The original would be
recorded slightly off the proper speed, but still readable (unless the timing
was off the other way on your drive unit). Copies would record at normal and
the software could detect that and refuse to run. An issue of the old
_Hardcore Computist_ magazine (core/apple pun intended) had instructions for
adding a speed control knob to a disc ][ drive unit so you didn't have to take
the cover off and use a jewelers screwdriver to adjust the potentiometer. In
college I occasionally made a couple extra bucks teaching Apple software
classes at computer stores. One customer had an issue with a drive unit that
was spinning to fast being unable to read the software. A little bit of
screwdriver work fixed it right up.

edit: Found some old digitized library of issues online. Not sure which issue
it was: [http://computist.textfiles.com/](http://computist.textfiles.com/)

~~~
kazinator
Also, using quarter track increments for unusual spacing or staggering of the
writes.

(IIRC, the movement of the floppy head was controlled by software stepping of
a stepper motor. The motor had four steps to move from one track to another.)

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evantahler
My favorite were the old age verification systems. I remember my dad had the
original? Leasure Suit Lary, and you had to prove you were both authentic and
of age.

Authentic: enter the 5th word on page 7 of the instructions (easily foiled by
a copy machine)

Of Age: who won the 1978 World Series? What is a 6th grader to do there? Phone
an uncle? Go to a library or book store? I breakable... Pre internet anyway :)

~~~
throwaway7767
The best part was how US-centric all the age verification questions were.
Questions about US politicians, american football scores etc.

Luckily they were all multiple-choice so over time fourteen year old me
learned the answers.

------
sgt101
I remember Elite on the ZX Spectrum had a novel scheme : a prism that you held
up to the screen after loading the game to read a challenge code. Quite
effective in that manufacturing a similar bit of plastic was beyond the ken of
most teenagers.

Here's the wikipedia page :
[https://en.wikipedia.org/wiki/Lenslok](https://en.wikipedia.org/wiki/Lenslok)

Seems to me that modern displays know how big and high res they are so could
calibrate the challenge to the lens lock size, so perhaps this brand of
weirdness will ride again!

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hrnnnnnn
I used to copy my friends' Amiga games, and by far the trickiest was one of
the Worms games. The code book was black paper with glossy black text, making
it almost impossible to scan or photograph.

I settled on figuring out the most freqently used page and copying it out by
hand, my mum reading out the numbers as I wrote them down. Good times.

~~~
LeoPanthera
Someone I know copied those with a flashlight and a polaroid camera.

------
StanislavPetrov
I was always partial to the copy protection in Alternate Reality: The City

>The first game, The City, also featured a novel[citation needed] anti-copying
technique. The program disks could be copied though the standard methods and
the copy would appear to work. However, not long after the player began the
game, their character would become weaker and weaker and then die from an
apparent disease.

[https://en.wikipedia.org/wiki/Alternate_Reality_(series)#Tec...](https://en.wikipedia.org/wiki/Alternate_Reality_\(series\)#Technology)

~~~
detaro
Settlers III broke the game similarly. You could start playing, but once you
got to manufacturing weapons for your soldiers the iron smelters produced pigs
instead of iron bars and you were stuck. (and few other, similar "bugs")

~~~
danbolt
They get points for the pun, too!

~~~
sgift
And minus points for their copy protection scheme sometimes stopping originals
from working. I buyed Settler III and it didn't work correctly (trees wouldn't
grow back), so I phoned their support and they told me that that was the copy
protection scheme in action. Great work ... thanks. At least they fixed it in
an update.

------
webtechgal
Wasn't there some method where a (physical) hole was made somewhere
(presumably in an unused track/sector) in the floppy so that the original
floppy would work, but disk-to-disk copy operation would fail?

Then, at some point in time came along those (parallel port pass-through)
dongles - I think they used to be called HASP (HArdware for Software
Protection).

~~~
joezydeco
HASP still exists, it's a USB key now:

[https://sentinel.gemalto.com/software-
monetization/sentinel-...](https://sentinel.gemalto.com/software-
monetization/sentinel-hasp-hl/)

~~~
webtechgal
Ah, so USB is what it is at now! I think one of the first movers in the HASP
sector was an Israeli company, called Alladin Technologies or something -
don't know if they're still around.

~~~
reitanqild
Used HASP dongles as late as 2012 for some realtime camera software. Alladin
seems familiar too but I cannot say for sure if it was that or another.

Suffice to say: for being Digital Restrictions Managements tools they worked
amazingly well, we had far more issues with activating Windows downgrade
licenses and least but not last individual RHEL licenses :-/

------
Nr7
Earlier discussion:
[https://news.ycombinator.com/item?id=9151275](https://news.ycombinator.com/item?id=9151275)

------
ghostDancer
I remember "Manic Miner" for Spectrum had a card with a colour matrix[0] and
you had to enter the correct one to play, in that time colour copies were not
available or more expensive than the game.
[0][http://archive.worldofdragon.org/index.php?title=Manic_Miner](http://archive.worldofdragon.org/index.php?title=Manic_Miner)

------
Sarkie
Metal Gear Solid had a good one, where the radio frequency was on the back of
the game art to progress in the game.

------
vblord
lol. That brings me back. I actually own a physical copy of "Don't Copy That
Floppy" on VHS. Coincidentally we stole it from our computer teacher when I
was a little kid.

~~~
Waterluvian
It was the first video I ever saw run on a computer. I got it on a Nautilus CD
and played on my Macintosh LC3. Only 8MB of RAM so it was like 160x120
resolution or something.

------
jonathankoren
The original Sid Meier's Pirates would ask you when with Spanish treasure
fleet or silver train would arrive somewhere on some date. If you answered
wrong, the game would still play, but you would begin at a distinct
disadvantage. A skeleton crew and a leaking pinnace (the smallest ship) if I
remember correctly.

------
jrockway
I remember playing Railroad Tycoon as a kid. I never realized that the train
it showed on startup was copy protection. I just thought it was a stupid
guessing game that they threw in as a bonus or something, like they wanted to
make sure you knew all the locomotive types before you got to them in the
game.

~~~
themaninthedark
I remember that, lost my manual but played it so much I knew the trains by
heart. Same with Civilization.

~~~
thaumasiotes
Civilization has the special trait that all of the copy-protection questions
have their answers available in-game through the civilopedia. I always thought
that was funny.

------
rhizome
Old school here is analog codewheel and "third word on page 75" old school
hardcopy schemes (tl;dr), but I never would have played Zork III without
CopyIIPC.

------
flyinghamster
Robotwar (a programming game in which you program robots in a vaguely BASIC-
like language and then let them fight in an arena) had a copy-protection
scheme that could be defeated by, as I vaguely recall, breaking into a DOS
prompt and saving files to cassette, then transferring them to a normal DOS
disk.

------
MattSteelblade
I remember having to do this for Sid Meier's Civilization for DOS. A few turns
into the game, it would ask a trivia question that was answered in the manual
(which of course was missing). Eventually got good at answering the questions
as the game would end if you failed.

------
spacemanmatt
I cut my assembler/hardware teeth diagnosing and patching the scheme
protecting a PC game called Zany Golf. All it had was a bad block check, and a
Phrack article on catching INT13 was all I needed to short-circuit the
validation routine. Good times.

------
amelius
Another technique might be to randomly destroy sectors on the back of the
floppy disk, e.g., using a laser. Then format the back of the disk, and record
the locations containing errors, and store these locations on the front side
of the disk.

------
realkitkat
DayDream BBS used to have a copy protection mechanism where when it detected
being a pirated copy, it silently enabled 'shell' command for all the BBS
users. I imagine that gave a pause to a few Sysops! :)

------
jrnichols
years ago, I pirated a copy of Half Life. It had what I could only assume was
a way to detect cracked versions. Remember the long train ride at the
beginning? That goes into the canyon and finally stops at the train platform
with the guard standing outside? The guard that then has to open the door? In
the version that I found, the guard didn't open the door. The guard fell over
dead.

I tried again and again and the guard would still fall over dead every time.
Wasn't sure if I was going crazy, or if I had just been trolled by a game
developer somehow.

~~~
rangibaby
Crysis Warhead did this:
[https://youtu.be/W4ST2nbZp30](https://youtu.be/W4ST2nbZp30)

------
phjesusthatguy3
I had a copy (ISEPIC cart) of Beach Head II for C64. When I copied that floppy
I ended up with a long black-on-green screed about how copying games was
wrong. It surprised the hell out of me.

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DoubleGlazing
Wasn't there one where you were given a plastic prism and you had to look at
the screen through that prism to see a number which you typed in?

Without the prism it just looked like random dots.

I might be imagining this.

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kazinator
Did these code wheel things work? All it takes is someone to go through the
wheel positions and type out all the words to a plain lookup table that can be
circulated as a text file.

~~~
Delpin0
They worked because there was no real internet to speak of. Yes, you could put
that text file on a floppy or print them out, but outside of your friends,
there was no real simple way to spread that information. BBS distribution was
also so small it would not have been a thing.

~~~
blincoln
Additionally, most(?) of the code wheels had multiple discs stacked together.
i.e. it wouldn't be a two-dimensional lookup table, but three- or four-. IMO
it would be more likely for someone to write a simple software utility to
emulate it, but it would probably be simpler than that to just remove the
check from the game :).

------
DoubleGlazing
Where in Time is Carmen Sandiego on the Amiga came with a pocket encyclopedia
which was both part of the game and a copy protection mechanism.

