Creative ideas for copy protection?

[andycadley]

am i not allowed to build and sell HARDWARE that i spent good time and money on?.. and sell it with FREE software pre-burned on the eeprom?
..i do not see a software licence (eg GPL,EULA) anywhere in relation to that game saying i cant...

Software, like most things, is copyrighted by it's creator by default. If there is not an explicit agreement that you can do it, then no you cannot. There is no requirement for any kind of written license agreement.

[Brocky]

am i not allowed to build and sell HARDWARE that i spent good time and money on?.. and sell it with FREE software pre-burned on the eeprom?
..i do not see a software licence (eg GPL,EULA) anywhere in relation to that game saying i cant...

Software, like most things, is copyrighted by it's creator by default. If there is not an explicit agreement that you can do it, then no you cannot. There is no requirement for any kind of written license agreement.

that goes in the face of ALL i have read and seen around software licencing... why do people on github include licences then?.. why do game companies have huge EULAs? why have i been told i should be including licences with my code if i dont want it stolen?
theres no copyright or trademarks anywhere to be seen...no on the game.. not on itch.. not on the creators website... whats to say i didnt write it and he stole it from me and is passing it off as his own? ....(just another example!)

without any licences it makes the piracy topic a very gray area

[Prodatron]

Anyway would be cool if AndyCadley is right by default.

[Cwiiis]

am i not allowed to build and sell HARDWARE that i spent good time and money on?.. and sell it with FREE software pre-burned on the eeprom?
..i do not see a software licence (eg GPL,EULA) anywhere in relation to that game saying i cant...

Software, like most things, is copyrighted by it's creator by default. If there is not an explicit agreement that you can do it, then no you cannot. There is no requirement for any kind of written license agreement.

This is correct, but in practice doesn't matter unless you have a lot of time and money to hire legal professionals to enforce your copyright...

For those saying "just report to eBay", I did that and in both very obvious cases, they found no terms had been violated - again, unless you have the money for legal representation, there's not much you can do except to appeal to the conscience of the offenders.

In both cases I was made aware of, the sellers have agreed to stop pirating my game - but every lost sale when you're only selling double figures is acutely felt. It's a shame that this is a thing in such a niche hobby.

For what it's worth, I'll likely fingerprint later releases and delay any free digital releases, as well as put splash screens on digital releases to inform people of the situation. I don't think current pirates are explicitly trying to do harm, but I do think they know what they're doing is sketchy and they're being willfully ignorant to avoid confronting the consequences of their actions.

I'll start also listing on eBay, now that selling is free (in my region) - I find it especially annoying that one of the repros was being sold for not much less than I'm selling the full boxed game, but there was no cartridge shell, no manual, no box... I may start offering cart-only for a reduced rate as I can do smaller batches economically (I need to do boxes at least 20 at a time really, carts I can do 5 at a time). I'm not selling anything at a price that makes significantly undercutting me worthwhile and the quality difference is likely to be vast (because I care and pirates, by virtue of what they're doing, don't).

Now back on topic;

I'm aware that any copy protection on a gx4000 game is either easily circumvented or too expensive/awkward, so I think what's interesting is what can you do easily to slow/stop the laziest pirates.

My idea that was mentioned that, yes, may break when emulators get more accurate, was not initialising the CRTC fully on ROM releases. This effectively makes roms work on emulators and c4cpc, which both initialise a bunch of CRTC registers that aren't initialised on a real machine with no firmware. I discovered that by accident, but it's a very easy (and easily defeated) anti-piracy measure.

Another idea is to use a bank checksum xor'd with a calculated value to initialise a bunch of gameplay variables - then you can fingerprint your roms and use that fingerprint to display ownership data. Again, it's easily defeated, but not *as* easily - especially as you can employ this variously throughout the code. This is only a deterrent, but it does mean unaltered pirated copies will display who dumped the rom. A problem with that is that if someone only partially or incorrectly cracks it, it may just look bad for the game rather than the pirate.

[lightforce6128]

Another idea builds on the ones already discussed: If the software is personalized, e.g. up to the level that it checks hardware components besides only showing a note on the start screen, then it would be clearly visible for everyone if the software is sold to another person - it even may not work on the other hardware. I know that there are not so many CPC models, but there are different hardware parts that can be distinguished (e.g. CRTC). And there might be also extension hardware whose existence or non-existence could be checked. Although these are only a few bits of information here and there, it will rapidly grow to divide down the possible target systems in quite small groups. Especially the name in the start screen will create groups with only a few, often only one member.

This requires some infrastructure: On ordering the buyer has to give some information about his hardware. This could be gathered with a small open source tool. While this is a bit complicated, this might still work in our community. Then a specialized build process uses the acquired information to create a personalized software version that runs only on one device. Also this is a bit complicated, but it will get worse ...

Usually a software developer would recognize that "check hardware" and "display buyer name" are two things separated from the rest of the software, put both in sub functions and call them at the right time. If programmed like this, this kind of protection can easily be removed with a debugger. So the idea is to do something similar as JavaScript code obfuscation: Spread the code to multiple locations, make heavy use of variables and registers set because of another reason, and do everything multiple times. Although this kind of code can still be "cleaned" from the protection, it will be a nightmare even for a skilled programmer.

While describing this method is simple, applying it is quite difficult. For this reason I want to throw in some technical terms: aspect oriented programming (AOP) with a bunch of join points, weaving different code parts into each other, and UML metamodels to separate the processes for protection and other parts of the code. A software process that makes use of this could automatically duplicate and spread software parts. Even better: something like libraries could be build up to move from ad-hoc implementations to defaults that could be improved over time. Even if one solution gets broken, it could be replaced or completed with another, new method. This kind of software protection development would be on a complete different level.

But who implements the needed tools?
And is it worth the effort?

[mr_lou]

@lightforce6128  
Playing around with creative copy protection methods can be just as intriguing and fun for the hobbyist as creating a CPC game project. So "worth the effort" is an abstract question.
I think it's an interesting topic, and fun to see what's possible.

It's definitely been worth it for the Atari Jaguar developer I mentioned. He has effectively prevented people from turning his digital downloads into physical cartridges.
Possible to circumvent? Well of course. Everything is. But it's not something the average Joe knows how to do.

@Brocky 
All creative works that anyone makes automatically becomes the Intellectual Property (IP) of the creator. This goes for music, graphics, games, books, whatever.
It is illegal to download music and sell it on CD's, or download graphics and sell printed posters of it, or download games and sell your own copies. This regardless of whether all of those files are free or not. They're still the IP of the owner, and you're not allowed to do anything with someone else's property without their explicit permission.
If you wanna test this, just try using any IP (even a small one) owned by Nintendo or Disney. Good luck. ;-)

For a small developer on a niche classic platform like the CPC, as @Cwiiis says, it's very unlikely to have any consequences though.

Amateur musicians like myself have it easier. Some years back, a guy took my music and sold it. There was a lawfirm eager to take over probono, I had to turn them down. I could easily have let them handle everything, but it would have resulted in big fines for the guy. But I did regret that decision after ending up spending weeks on it. So next time there'll be no mercy.

[McArti0]

OnFirst, write down what the minimum costs of craking the security should be.
New hardware setup? Recompile software?
How many man-hours should it take to crack the security?

[dodogildo]

Sorry, can't stay off-off-topic but:
Isn't it a bit unreasonable to let everyone download the dsk or cpr for free while trying to sell the physical version? If you only give the files to those who pay, no one will want to share them with anyone else. Indeed, there are many physical editions in the C64 and MSX scene, and it is impossibly hard to find pirated copies. Because people are sensitive about protecting what they paid for.

[mr_lou]

Isn't it a bit unreasonable to let everyone download the dsk or cpr for free while trying to sell the physical version?

Seems to me it's more a less the standard nowdays to offer a physical "collector's edition" version of the game, while also offering "pay-what-you-want" download versions without all the physical accessories.
Some care about collecting, while others don't. So no, that's not unreasonable at all. Merely targeting two groups of people.


Trying yet again to go back on topic (this is getting ridiculous):

What kind of things can actually be detected on the CPC?
We can detect wether something runs on an emulator or real hardware, right?
And we can see how much RAM is available, right?
And I was told elsewhere (because it's difficult getting a straight answer to simple questions here) that it's also rather easy to detect the presense of tape/disc/cartridge.
Is there any way to detect the presense of a C4CPC? And/or M4 card?

Has anyone made a CPC plus cartridge yet that includes some kind of savedata chip? For the player to save his progress on? Because such a savechip could also be used as a way to check if it's a genuine copy I guess.

[arnoldemu]

My idea that was mentioned that, yes, may break when emulators get more accurate, was not initialising the CRTC fully on ROM releases. This effectively makes roms work on emulators and c4cpc, which both initialise a bunch of CRTC registers that aren't initialised on a real machine with no firmware. I discovered that by accident, but it's a very easy (and easily defeated) anti-piracy measure.

My emulator doesn't initialise the CRTC values as per the real hardware and likewise some others so I think you might frustrate the legit users more who will not understand why the game doesn't work for them on their chosen emulator or setup.

I relate to how your feeling about it all.

I made a C64 conversion of a game which I sold through Chronosoft. Within a week or so there was a hacked version on csdb and that got far more downloads than sales. I never expected to get many sales from it but this just stopped them entirely and I've not done a c64 game since because it annoyed me that much.

I also sold a CPC version through Chronosoft which made hardly anything (about £20 total) so I've resigned myself that I'm not going to make any money on any of the games I do.

I do have an idea.

I would go for a positive startup screen which says 'this game is registered to <person>. Thank you for supporting me and look out for future games from me at itch.io' . It makes it personal to the legit buyer and in some way indicates to non-legit it's not for them. I would then embed a unique id related to that person. I would implement some kind of checksum of the data that checks to see if there is modifications to the code to try and avoid people patching and I would also encrypt the data. Finally I'd add in checks which make the game very difficult, or not possible to complete if any of the checks fail, but it does it silently. Then perhaps if you offer to support each game you can detect it's been hacked about and get the person coming to you to buy a legit version.

That could work. Any other detection method or reliance on some kind of emulator inaccuracy might just be unreliable but also might incur bad reviews of your game when that is not what you intend.

[mr_lou]

My idea that was mentioned that, yes, may break when emulators get more accurate, was not initialising the CRTC fully on ROM releases. This effectively makes roms work on emulators and c4cpc, which both initialise a bunch of CRTC registers that aren't initialised on a real machine with no firmware. I discovered that by accident, but it's a very easy (and easily defeated) anti-piracy measure.

My emulator doesn't initialise the CRTC values as per the real hardware and likewise some others so I think you might frustrate the legit users more who will not understand why the game doesn't work for them on their chosen emulator or setup.

I think you misunderstand. The fact that your emulator doesn't initialise the CRTC is exactly what Cwiiis is counting on - because that would exactly mean that the game would run on your emulator - but not real hardware.
(And again - disregard personal opinions - this is only a theoretical talk)

Dev creates own physical cartridge + offers a digital download version. Therefor wants to prevent people simply turning the digital download into a real cartridge. Not fully initializing the CRTC on the digital download version will prevent people doing that, exactly because emulators don't do that either.
So yes, that is in fact one way of doing it.
(Although I guess it would also prevent the digital download game working on a C4CPC, so that part would have to be considered as well somehow - if possible. No idea if it's possible to detect a C4CPC. But again: Just talk. Just initial theoretical talk about what's possible).

[arnoldemu]

Isn't it a bit unreasonable to let everyone download the dsk or cpr for free while trying to sell the physical version?

Seems to me it's more a less the standard nowdays to offer a physical "collector's edition" version of the game, while also offering "pay-what-you-want" download versions without all the physical accessories.
Some care about collecting, while others don't. So no, that's not unreasonable at all. Merely targeting two groups of people.


Trying yet again to go back on topic (this is getting ridiculous):

What kind of things can actually be detected on the CPC?
We can detect wether something runs on an emulator or real hardware, right?
And we can see how much RAM is available, right?
And I was told elsewhere (because it's difficult getting a straight answer to simple questions here) that it's also rather easy to detect the presense of tape/disc/cartridge.
Is there any way to detect the presense of a C4CPC? And/or M4 card?

Has anyone made a CPC plus cartridge yet that includes some kind of savedata chip? For the player to save his progress on? Because such a savechip could also be used as a way to check if it's a genuine copy I guess.

many things can be detected on a real CPC. The amount of RAM, which variant of the CRTC, which variant of the 8255, if floppy chip is present (not sure can detect if tape is present or not), which roms are connected, a lot of the various additional hardware devices, if the floppy disc controller is implemented to the lowest level, which roms are present and how various things decode the i/o ports, some of these tests are quick some are much much slower, so it depends on how long you want to spend doing these checks and all these can be disabled easily enough.

I expect it is possible to detect C4CPC if you take advantage of it's API for accessing the sdcard and I'd expect detecting an m4 would be fairly easy although I've not tried but again you are potentially putting off legit users potentially.

We can test some things to detect an emulator but they're unreliable and I'd expect that to stop working fairly quickly and some are very advanced and so close to real cpc you can't detect so I'm not sure how this helps.

When it comes to physical carts the hardware doesn't support write so any operations need to be done as reads so potentially a custom cart with a special chip that could be read would be some way to determine a legit cart but they'd need designing and manufacturing but it might put off some people selling them.

[arnoldemu]

My idea that was mentioned that, yes, may break when emulators get more accurate, was not initialising the CRTC fully on ROM releases. This effectively makes roms work on emulators and c4cpc, which both initialise a bunch of CRTC registers that aren't initialised on a real machine with no firmware. I discovered that by accident, but it's a very easy (and easily defeated) anti-piracy measure.

My emulator doesn't initialise the CRTC values as per the real hardware and likewise some others so I think you might frustrate the legit users more who will not understand why the game doesn't work for them on their chosen emulator or setup.

I think you misunderstand. The fact that your emulator doesn't initialise the CRTC is exactly what Cwiiis is counting on - because that would exactly mean that the game would run on your emulator - but not real hardware.
(And again - disregard personal opinions - this is only a theoretical talk)

I wouldn't rely on not initialising something. It's not reliable enough.

Real hardware, e.g. a GX4000, Plus, with a 'standard' cartridge which has an acid or the 74LS acid workaround also does not initialise hardware. The kind of cart people are selling on ebay as 'your game on a cart'.

Some emulators (e.g. Winape) does initialise the hardware, some others (e.g. Arnold) don't.

I expect the 16-in-1 sold on ebay also doesn't initialise the hardware.

The C4CPC menu system DOES initialise the hardware except you can also boot it via USB which I think DOESN'T initialise the hardware and by using a specific dip switch (that may as it shows a loading boot screen).

I don't know about the others like the M4 as I've not tested that.

[arnoldemu]

The only way I can see to prevent somebody from burning a cart is to ensure the cart they booted the machine from is not yours.

This method can still be hacked but might just be enough but does involve extra effort and work.

Provide the download as a disk. If you need the capacity of a cart use extra memory. At some point starting up the game or during the game scan the roms in the cart range and check they are the basic ones. Check all from 128-255!

This avoids nocart being used to put it onto a cart from a disc. You can also defeat nocart by using a 80 track double sided disc and filling it up even if it's with junk, just enough to make it beyond the capacity of nocart.

Then as has been said before offer the actual cart only direct through you and incentivise with extras.

[mr_lou]

@arnoldemu A lot of tech talk there. As far as I understand, basically you're saying to not offer a downloadable CPR file then? Only offer a downloadable DSK file? (And one's own physical cartridge edition as well of course).
Not saying that's a bad idea. Just making sure I understand you correctly.

[arnoldemu]

@arnoldemu A lot of tech talk there. As far as I understand, basically you're saying to not offer a downloadable CPR file then? Only offer a downloadable DSK file? (And one's own physical cartridge edition as well of course).
Not saying that's a bad idea. Just making sure I understand you correctly.

yes correct.

[andycadley]

@arnoldemu A lot of tech talk there. As far as I understand, basically you're saying to not offer a downloadable CPR file then? Only offer a downloadable DSK file? (And one's own physical cartridge edition as well of course).
Not saying that's a bad idea. Just making sure I understand you correctly.

yes correct.

Which might prevent pirate cartridges, but makes pirate disks easy. Unless you can write a disk format that commodity hardware cannot write, at which point you're back in the same boat as requiring some sort of external hardware add-on: production costs for the legit versions spiral just as much as for pirates.

[arnoldemu]

@arnoldemu A lot of tech talk there. As far as I understand, basically you're saying to not offer a downloadable CPR file then? Only offer a downloadable DSK file? (And one's own physical cartridge edition as well of course).
Not saying that's a bad idea. Just making sure I understand you correctly.

yes correct.

Which might prevent pirate cartridges, but makes pirate disks easy. Unless you can write a disk format that commodity hardware cannot write, at which point you're back in the same boat as requiring some sort of external hardware add-on: production costs for the legit versions spiral just as much as for pirates.

True but I don't think that any physical discs would be done and sold. Somebody would need to find error free 3" discs, a working 3" drive, write it to a 3" disc and print out a label and then I think it'd be less likely to command a high price on ebay.

[mr_lou]

The only way I can see to prevent somebody from burning a cart is to ensure the cart they booted the machine from is not yours.

This method can still be hacked but might just be enough but does involve extra effort and work.

Provide the download as a disk. If you need the capacity of a cart use extra memory. At some point starting up the game or during the game scan the roms in the cart range and check they are the basic ones. Check all from 128-255!

This avoids nocart being used to put it onto a cart from a disc. You can also defeat nocart by using a 80 track double sided disc and filling it up even if it's with junk, just enough to make it beyond the capacity of nocart.

Then as has been said before offer the actual cart only direct through you and incentivise with extras.

I love this idea! The dev will have to accept not being able to offer a downloadable CPR, but sacrifices has to be made, so it'll do. This is a great example of the kind of solution I was asking for. Thanks.

One could even expand on it a bit, and show an info screen if nocart was detected.

Excuse me sir, terribly sorry for interrupting your fine business here.
I just wanted to let you know that what you're doing here is actually not legal. No sir.
This game is in fact the Intellectual Property of <owner>, and you do not actually have permission to distribute it on your own cartridge solution.
There is already a fine cartridge edition offered online, etc etc....

[McArti0]

If you close the software in rp2354 you can make a compiler that will secretly change the code addressing/banking.

exp code z80

Org 100
Ld hl,(100)
Jp 100

In the sense of equ idea code:

Org 100
Ld hl,(200)
Jp 300

Real code 3x100 even after capturing from z80 pins it is not possible to burn it to EPROM

[Pollo]

Amsteam could be the solution for mr_lou.

It is a custom hardware, acting sort of like a security dongle. And it isn't documented, making it very hard for emulators to replicate.
That means that the crackers will have to work on real hardware. Not so easy for them.

After payment, the game is encrypted and delivered online. So there are no files or physical media that can be copied.

And the hardware uses an obscure Yamaha OPN3 sound chip. So even if if the game gets cracked somehow, it won't have any sound.

[BSC]

One idea: If you are doing cross-dev, you could create a build pipeline where you arrange the source code of your game in a way that, when building the game, some chunks of the source would be scrambled in a certain way, probably based on some random number. I think this would need some preparation on the source code to be done so that you end up with as many chunks as needed (see below). 

Imagine (for the purpose of this post, reality might differ) you have a source file which consists of 100 functions which are called from the game at arbitrary points. Further imagine that the position in memory of those functions does not matter for the game to work, they can be in any order / at any position. This should be true for a lot of code I think. If you now were to permutate (i.e. reorder them) those functions (imagine a lot of tiny source files for each of them) before assembling the binary, you would be able to create as many different versions of the binary as there are possibilities to permutate those functions. 

The permutations could be created using a random number generator, but I think then it would be important for it to be deterministic and collision free so that you are able to create as many unique sets of function orderings as there are functions. 

One example: Imagine you have 4 functions, fnA, fnB, fnC and fnD which are used by the game and can be at any position within the binary. If my math (4 factorial = 4×3×2×1 = 24) is not wrong, you have then 24 ways of ordering those 4 functions. The more functions, the more possible permutations. 8 functions would already yield 40320 possible ways of ordering them.

Each permutation of the functions would then be a unique identifier for that specific build of the game. One game could be made of ABCD, the next one ABDC and so on. This identifier can be linked to the buyer and enables you to reverse the process. Given a copy of your game, you can deduce the identifier by applying a process (i.e. running a yet-to-design-and-write small tool against the binary) which detects and prints the order of all scrambled functions, e.g. ABDC and, voila!, you know who bought it. The tool itself would need some knowledge of the scrambling, for example taking some samples from the binary and map this set of samples to the identifier, but this could be generated and appended to e.g. a file every time you create a new build.

If then someone publishes a copy of your game, you can just run that tool to deduce the identifier and compare with your existing set, yielding the original buyer. I would hope that this would prevent most people from sharing their version, knowing that it a) can be connected to exactly one buyer relatively easily and b) can not easily be turned into a version which can *not* be identified without reverse engineering (re-assembling) the game code.

[Prodatron]

That definitely sounds like the best methode ever! You can even do this with data areas, not only with functions (best to do it with both at the same time).
Every game or app has more than 10 functions and data areas which can be swapped in different orders, so 1000s of different versions should be possible. Maybe a nice idea for an Assembler option
It should be impossible for a cracker to hide the original source. Or would it? I think without disassembling the whole stuff, it's impossible to "crack" a game and to hide the origin buyer!
Yeah, then you can really fuck him

[Anthony Flack]

Putting code in your game that makes it not work on some hardware or combination of hardware, or breaks if I try to run it on a machine that differs from the one I registered, is the sort of thing that would make me go looking for a cracked version to run instead. Or not bother at all. 

It creates an incentive to crack the game, and inconveniences the small number of people who did give you money, not that there's any money to be made anyway. Anti-piracy locks are ANNOYING

[mr_lou]

What @BSC (and others) are describing is basically a hidden watermark. I.e. a way to identify who the specific copy of the game was sold to. It doesn't actually prevent piracy, and it's easy to register a game to a false name.
Not saying it's useless. Just pointing out I think there's a difference between a watermark and a lockout.

Comparing again with music, I can easily add hidden watermarks in my tracks, as a method to prove that I am the actual author. Or as a way to identify who I sent an early preview to. But it wouldn't prevent theft occurring. It would only reveal a name or nick that I can't trust. Not particular helpful.

@Anthony Flack Everything is annoying to everyone who wants things to be different. ;-) Piracy is annoying to gamedevs. Anti-piracy is annoying to pirates. Someone will have to yield.
It is true though, in my experience also, most of the anti-piracy methods out there doesn't affect the pirates at all, but do affect legal users. One example is DVD/Blu-ray movies where legal owners have to watch all of the anti-piracy messages before being allowed to watch the movie. That is silly. So yes, I agree some effort has to be made to consider not making life miserable for legal users.

Preventing people from turning a DSK into a nocart, while adding a friendly info screen about why, shouldn't annoy anyone other than those who insist the whole world has to bow down to their wishes. @arnoldemu 's idea is absolutely perfect for @Cwiiis ' scenario, I think.