http://scarybeastsecurity.blogspot.co.u ... egant.html
It's great to see that it's still inspiring people... 26 years on

Just in case people wanted to peruse the listing, I've put it into a text file... hope it is enlightening....jms2 wrote:That's really interesting - the blog post also links to a disassembly, which I didn't know was available online.
A footnote on copy protection:Coming nine years after Warren Robinett created his Adventure on the Atari VCS, Exile, which embraced much the same design philosophy but blew it all up to well-nigh absurdist proportions, feels like the logical end point of what he began. It’s hard to imagine a bigger, more fascinating, more daunting action-adventure than this one. And really, it’s hard to imagine why anyone would even want such a thing. Exile is packed full of so many creatures and puzzles and hidden nooks and crannies that its secrets have yet to be exhaustively cataloged, in spite of the best efforts of a small but devoted cult of fandom who have been at the job for a few decades now. Its warren of underground caverns just go on and on and on, with something new to discover behind its every twist and turn. How remarkable that the game’s programmers, Peter Irvin and Jeremy Smith, created this monster inside the most constrained platform of any of the games we’ve looked at since Robinett’s Adventure: a 32 K BBC Micro.
It’s likely that the majority of people who have played Exile have done so on versions that were literally impossible to complete. One other aspect of the game’s legend is its copy protection, which stands as the most devious of its era. Instead of simply booting you out of the game, the layers upon layers of protection, personally devised by Irvin and Smith, subtly alter the game to make it impossible to complete
I think the game was quite popular on both the c64 and amiga. A game with poor sales figures on either of those systems still probably outsells a 1988 BBC/electron best seller.davidb wrote:...though I don't know where he gets the idea that the majority of players experienced it on those platforms.....
It would be interesting to know the figures. I'm not disputing that they could be higher, but it often seems that Acorn users were a lot more vocal about the merits of the game.sydney wrote:I think the game was quite popular on both the c64 and amiga. A game with poor sales figures on either of those systems still probably outsells a 1988 BBC/electron best seller.
Can't be 100% sure, though we have an annotated disassembly and can see where the novella protection code used to be (and how it was removed). I would remain fairly confident that the Beeb disc images of Exile going around are intact and can be completed. In fact, there's a series of YouTube videos showing it played to completion on BeebEm, so I guess that's probably good enough proof.BigEd wrote:You're quite sure then there are no remaining subtle changes in the cracked game? It's almost a pity, as there might have been more to learn...
Strange the names that appear. I thought William Reeve worked on a non-Acorn port. Also I found somebody called Richard Williams: http://everygamegoing.com/landing/items ... le_V1.htmlRich Talbot-Watkins wrote:Matt Godbolt pointed me at this interesting blog post on Exile:
http://scarybeastsecurity.blogspot.co.u ... egant.html
It's great to see that it's still inspiring people... 26 years on
I guess this is the main problem with modern DRM; it just ends up p'''ing off your actual customers, It never prevents piracy.Kevin Edwards wrote: Nice idea, assuming it doesn't go badly wrong!.
Without wanting to go too OT, we did a similar thing with Banjo-Kazooie on the N64. There was a special chip on the cartridge that we could send data to and get back in a known encrypted / signed state. We passed data through it and used this to seed the game in various places. It was all quite subtle so some of the doors wouldn't open or a race would be impossible to beat. The pirate systems at the time, like Doctor 64, required the user to have at least one cartridge with the custom chip plugged in. Unfortunately for us another game, that will remain unnamed, came out shortly afterwards that was produced in vast quantities but ended up in the bargain bin and cheaply available.Rich Talbot-Watkins wrote:A good 20 years ago now, I worked on a game on the Playstation called Medievil. Sony had just introduced a library called Libcrypt, which took advantage of the fact that the Playstation hardware could read raw data from CDs, and that all releases were mastered with deliberately incorrect correction bits in certain parts of the disc. So, with Libcrypt, we were able to read values from the disc which would not be preserved in a copy (which would always be written with valid correction bits). This acted as a key, which we then used to generate all the magic values used in one of the levels well into the game. Result was that a copy appeared to function perfectly, until you were halfway into the game, at which point the broken level would start up and be largely unplayable, and certainly not allow the player to progress further.
Potentially. It is possible to be too clever for one's own good.sbadger wrote:I wonder if such a subtle and pernicious anti piracy scheme has ever backfired, in that it's damaged the reputation of a title.
If something was widely copied but the game came across as difficult or buggy ,word of mouth for actual prospective buyers would be poor?
I concur that the protection wasn't as strong as some of your earlier titles. At school, we got around it in a couple of evenings, whereas some of your earlier efforts defeated us entirely without the use of hardware hackery. (Lacking the money for anything snazzy, and permission to do anything too invasive to the school's computers, we simply ran a DIP switch to some of the link headers so we could write-protect the sideways RAM then map it in place of the OS.)Kevin Edwards wrote:Yes, Exile ( tape ) was one of the last BBC Micro games i protected - personally, i'd moved on to other projects and platforms, but did this as a one off. The authors were keen to have their game as secure as possible, but it also had to work on the Master 128, B+ etc. Yes, i did have to dilute the protection to ensure the decoders would work on all hardware variations.