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

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.

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

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://arstechnica.com/security/2011/03/ask-ars-how-can-i-sa...

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.

> 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.

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/

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.)

Kinda off topic, but that reminds me of some early virus/es that would run the floppy r/w head re-calibrate command in an infinite loop and if not stopped soon, would ruin the head alignment, rendering the drive permanently unusable.

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 :)

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.

The age verification question is a nice reminder of just how incredible the Internet is.

Leisure Suit Larry 1 (and 3) also had a secret key combination that you could press to skip the age verification check completely.

There weren't a lot of questions on LSL though, so you could get memorize the right answers with trial and error.

Trial and error. I literally memorized the correct answers as a 2nd grader. It's not like there was anything else to do but be bored, hehe

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

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!

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.

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

I had a hand-drawn copy of, I think, the Space Quest IV code page.

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...

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")

Newer games do some similar things. Serious Sam 3 had an invulnerable enemy follow you around and attack you, while Batman Arkham Asylum took away the ability to glide with the cape.

They get points for the pun, too!

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.

The astonishing text adventure Amnesia by Thomas M. Disch (Electronic Arts, 1986) also did something like this. The copy appeared to let you play (with an obnoxious codewheel on top of a custom disk format), but you got stuck in a hotel room you can't leave. https://en.wikipedia.org/wiki/Amnesia_(video_game) and an amazing writeup giving some background of Disch and the game is at www.filfre.net/2014/09/amnesia/ For the time, really an amazing game, if frustrating and flawed in places.

How did it detect copying?

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).

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

https://sentinel.gemalto.com/software-monetization/sentinel-...

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.

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 :-/

Yes, it was. I remember both the names Alladin and HASP from old computer mag ads (e.g. BYTE, PC Magazine).

Alladin makes usb tokens to store A3 certificates

Throwaway to answer but: I remember that the "5 1/4" floppy disk of the game "Lemmings" had a hole somewhere that was blocking the regular copy programs (like diskcopy).

Exactly. Some Financial Accounting packages selling here in India back then used that trick.

My former boss (in IT since 1983, from whom I got initiated to hacking) wrote a disk copy program that would copy the source disk sector to sector, ignoring any error along the way, that dealt with the hole in short order. (He used it to make backup copies for legit users, and not for piracy.)

Wasn't there a dongle for an old computer like a spectrum or Dragon32 that you could emulate by waggling your joystick whilst the game loaded?

Earlier discussion: https://news.ycombinator.com/item?id=9151275

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

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

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.

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.

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.

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.

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

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.

Did the same thing with RRT. A great game, and the gameplay still holds up, although the station limit is annoying. Even the signal system is fun once you learn how to use it.

Same with Master of Orion (surprised it wasn't mentioned yet)

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.

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.

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.

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.

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.

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! :)

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.

Crysis Warhead did this: https://youtu.be/W4ST2nbZp30

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.

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.

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.

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.

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 :).

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.