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older copy protection...

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  older copy protection... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-05-13 15:55 -0700
    Re: older copy protection... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-05-14 16:04 -0700
      Re: older copy protection... Al Kossow <aek@bitsavers.org> - 2025-05-14 16:37 -0700
        Re: older copy protection... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-05-18 01:21 -0700
          Re: older copy protection... John Levine <johnl@taugh.com> - 2025-05-19 02:09 +0000
            Re: older copy protection... Terje Mathisen <terje.mathisen@tmsw.no> - 2025-05-19 09:08 +0200
              Re: older copy protection... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-05-25 21:13 -0700
                Re: older copy protection... Vir Campestris <vir.campestris@invalid.invalid> - 2025-06-05 17:09 +0100
                  Re: older copy protection... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-06-05 14:52 -0700
                    Re: older copy protection... mitchalsup@aol.com (MitchAlsup1) - 2025-06-05 22:35 +0000
                      Re: older copy protection... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-06-06 12:33 -0700
    Re: older copy protection... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-06-05 14:49 -0700
      Re: older copy protection... "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-06-06 12:34 -0700

#111611 — older copy protection...

Does anybody know the hardware used to create the copy protection in the 
old Dungeon Master game?

http://dmweb.free.fr/community/documentation/copy-protection/copy-protection/

http://dmweb.free.fr/community/documentation/copy-protection/copy-protection-atari-st/

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#111618

On 5/13/2025 3:55 PM, Chris M. Thomasson wrote:
> Does anybody know the hardware used to create the copy protection in the 
> old Dungeon Master game?
> 
> http://dmweb.free.fr/community/documentation/copy-protection/copy- 
> protection/
> 
> http://dmweb.free.fr/community/documentation/copy-protection/copy- 
> protection-atari-st/
> 
> 
  Does anybody know the hardware? Here is a relevant snip from the links:
_________________
As the developer of both Dungeon Master and the software portion of its 
copy protection, I knew that eventually the copy protection would be 
broken, but that the longer it held out the less damage we would suffer 
when it was broken. We had the advantage of owning the patent on a 
floppy-disk copy protection scheme that required a $40,000 specialized 
hardware device to write the disks. It was impossible to create a disk 
image without this hardware, and the hardware itself was out of 
production. That meant that as long as there were enough layers on the 
copy protection, and these layers took long enough to crack, the only 
way to own the game was to buy it. The copy protection scheme took a 
couple of weeks to create, and while this added cost to the production 
without adding value for the customer, it was time well spent. The copy 
protection was based on many redundant, overlapping and isolated checks 
and cross checks. The copy protection was developed with the assumption 
that the cracker would be armed with a hardware emulator and developed 
with an awareness of the capabilities and limitations of the commonly 
available emulators of the time.
_________________

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#111619

On 5/14/25 4:04 PM, Chris M. Thomasson wrote:
> On 5/13/2025 3:55 PM, Chris M. Thomasson wrote:
>> Does anybody know the hardware used to create the copy protection in the old Dungeon Master game?

>   Does anybody know the hardware? Here is a relevant snip from the links:
> _________________
> As the developer of both Dungeon Master and the software portion of its copy protection, I knew that eventually the copy protection would be 
> broken, but that the longer it held out the less damage we would suffer when it was broken. We had the advantage of owning the patent on a 
> floppy-disk copy protection scheme that required a $40,000 specialized hardware device to write the disks. It was impossible to create a 
> disk image without this hardware, and the hardware itself was out of production. That meant that as long as there were enough layers on the 
> copy protection, and these layers took long enough to crack, the only way to own the game was to buy it. The copy protection scheme took a 
> couple of weeks to create, and while this added cost to the production without adding value for the customer, it was time well spent. The 
> copy protection was based on many redundant, overlapping and isolated checks and cross checks. The copy protection was developed with the 
> assumption that the cracker would be armed with a hardware emulator and developed with an awareness of the capabilities and limitations of 
> the commonly available emulators of the time.
> _________________


this has been discussed on the Applesauce discord

"sector has that criss-cross pattern between the 1st and 2nd signal bands? That is use to put flux transition right at the edge of bitcell 
windows. Slight motor speed fluctuations mean that the nibbles in the area will shift between different values every time you read the sector. "

so very precise timing changes on only one sector of the disk to make non-deterministic recovered bits.

the "bands" referred to is looking at a histogram of the flux transition times of the track

"It was impossible to create a disk image without this hardware"

The disk has been cloned on the Applesauce.

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#111625

On 5/14/2025 4:37 PM, Al Kossow wrote:
> On 5/14/25 4:04 PM, Chris M. Thomasson wrote:
>> On 5/13/2025 3:55 PM, Chris M. Thomasson wrote:
>>> Does anybody know the hardware used to create the copy protection in 
>>> the old Dungeon Master game?
> 
>>   Does anybody know the hardware? Here is a relevant snip from the links:
>> _________________
>> As the developer of both Dungeon Master and the software portion of 
>> its copy protection, I knew that eventually the copy protection would 
>> be broken, but that the longer it held out the less damage we would 
>> suffer when it was broken. We had the advantage of owning the patent 
>> on a floppy-disk copy protection scheme that required a $40,000 
>> specialized hardware device to write the disks. It was impossible to 
>> create a disk image without this hardware, and the hardware itself was 
>> out of production. That meant that as long as there were enough layers 
>> on the copy protection, and these layers took long enough to crack, 
>> the only way to own the game was to buy it. The copy protection scheme 
>> took a couple of weeks to create, and while this added cost to the 
>> production without adding value for the customer, it was time well 
>> spent. The copy protection was based on many redundant, overlapping 
>> and isolated checks and cross checks. The copy protection was 
>> developed with the assumption that the cracker would be armed with a 
>> hardware emulator and developed with an awareness of the capabilities 
>> and limitations of the commonly available emulators of the time.
>> _________________
> 
> 
> this has been discussed on the Applesauce discord
> 
> "sector has that criss-cross pattern between the 1st and 2nd signal 
> bands? That is use to put flux transition right at the edge of bitcell 
> windows. Slight motor speed fluctuations mean that the nibbles in the 
> area will shift between different values every time you read the sector. "
> 
> so very precise timing changes on only one sector of the disk to make 
> non-deterministic recovered bits.
> 
> the "bands" referred to is looking at a histogram of the flux transition 
> times of the track
> 
> "It was impossible to create a disk image without this hardware"
> 
> The disk has been cloned on the Applesauce.

Thanks! I need to ponder on this. Thanks again.

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#111636

According to Chris M. Thomasson <chris.m.thomasson.1@gmail.com>:
>> "It was impossible to create a disk image without this hardware"
>> 
>> The disk has been cloned on the Applesauce.
>
>Thanks! I need to ponder on this. Thanks again.

The usual approach was to patch the program to disable the code
that checked the copy protection.



-- 
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly

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#111638

John Levine wrote:
> According to Chris M. Thomasson <chris.m.thomasson.1@gmail.com>:
>>> "It was impossible to create a disk image without this hardware"
>>>
>>> The disk has been cloned on the Applesauce.
>>
>> Thanks! I need to ponder on this. Thanks again.
> 
> The usual approach was to patch the program to disable the code
> that checked the copy protection.

The usual "protection" against this was to distribute the checking code 
across both time and space, only loading/decrypting the next part after 
verification.

Terje


-- 
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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#111804

On 5/19/2025 12:08 AM, Terje Mathisen wrote:
> John Levine wrote:
>> According to Chris M. Thomasson <chris.m.thomasson.1@gmail.com>:
>>>> "It was impossible to create a disk image without this hardware"
>>>>
>>>> The disk has been cloned on the Applesauce.
>>>
>>> Thanks! I need to ponder on this. Thanks again.
>>
>> The usual approach was to patch the program to disable the code
>> that checked the copy protection.
> 
> The usual "protection" against this was to distribute the checking code 
> across both time and space, only loading/decrypting the next part after 
> verification.

Indeed. Let them get through some of the game, then BAM, they are 
frozen, or crash, whatever...

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#111913

On 26/05/2025 05:13, Chris M. Thomasson wrote:
> 
> The usual "protection" against this was to distribute the checking code 
> across both time and space, only loading/decrypting the next part after 
> verification.

One subtle protection method was to make the game really hard to play 
when parts of the protection system had been disabled.

Andy

-- 
Do not listen to rumour, but, if you do, do not believe it.
Ghandi.

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#111915

On 6/5/2025 9:09 AM, Vir Campestris wrote:
> On 26/05/2025 05:13, Chris M. Thomasson wrote:
>>
>> The usual "protection" against this was to distribute the checking 
>> code across both time and space, only loading/decrypting the next part 
>> after verification.
> 
> One subtle protection method was to make the game really hard to play 
> when parts of the protection system had been disabled.

The cracker, hacker, thinks I got it! Well, I think so... I get to 
actually play the game, but its on ultra hard. ;^)

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#111916

On Thu, 5 Jun 2025 21:52:37 +0000, Chris M. Thomasson wrote:

> On 6/5/2025 9:09 AM, Vir Campestris wrote:
>> On 26/05/2025 05:13, Chris M. Thomasson wrote:
>>>
>>> The usual "protection" against this was to distribute the checking
>>> code across both time and space, only loading/decrypting the next part
>>> after verification.
>>
>> One subtle protection method was to make the game really hard to play
>> when parts of the protection system had been disabled.
>
> The cracker, hacker, thinks I got it! Well, I think so... I get to
> actually play the game, but its on ultra hard. ;^)

What:: no IDKFA ?!?

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#111917

On 6/5/2025 3:35 PM, MitchAlsup1 wrote:
> On Thu, 5 Jun 2025 21:52:37 +0000, Chris M. Thomasson wrote:
> 
>> On 6/5/2025 9:09 AM, Vir Campestris wrote:
>>> On 26/05/2025 05:13, Chris M. Thomasson wrote:
>>>>
>>>> The usual "protection" against this was to distribute the checking
>>>> code across both time and space, only loading/decrypting the next part
>>>> after verification.
>>>
>>> One subtle protection method was to make the game really hard to play
>>> when parts of the protection system had been disabled.
>>
>> The cracker, hacker, thinks I got it! Well, I think so... I get to
>> actually play the game, but its on ultra hard. ;^)
> 
> What:: no IDKFA ?!?

Humm. Perhaps the "almost" cracked version does not allow for that? No 
BFG's? ;^)

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#111914

On 5/13/2025 3:55 PM, Chris M. Thomasson wrote:
> Does anybody know the hardware used to create the copy protection in the 
> old Dungeon Master game?
> 
> http://dmweb.free.fr/community/documentation/copy-protection/copy- 
> protection/
> 
> http://dmweb.free.fr/community/documentation/copy-protection/copy- 
> protection-atari-st/
> 
> 

  The detection of a single bit with changing value is enough for the 
program to consider the disk as original

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#111918

On 6/5/2025 2:49 PM, Chris M. Thomasson wrote:
> On 5/13/2025 3:55 PM, Chris M. Thomasson wrote:
>> Does anybody know the hardware used to create the copy protection in 
>> the old Dungeon Master game?
>>
>> http://dmweb.free.fr/community/documentation/copy-protection/copy- 
>> protection/
>>
>> http://dmweb.free.fr/community/documentation/copy-protection/copy- 
>> protection-atari-st/
>>
>>
> 
>   The detection of a single bit with changing value is enough for the 
> program to consider the disk as original

To hack it, I think they put in a pseudo-rng to simulate checking the 
fuzzy bit.

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