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* Copy protection of the floppies
@ 2003-11-25  5:37 Pravin Nanaware , Gurgaon
  2003-11-25  9:07 ` Murray J. Root
                   ` (5 more replies)
  0 siblings, 6 replies; 16+ messages in thread
From: Pravin Nanaware , Gurgaon @ 2003-11-25  5:37 UTC (permalink / raw)
  To: linux-kernel

Hi All,

1> Could somebody suggest me the way to protect floppy from copying it's
contents. 
2> If not possible, will it be possible to make the copied floppy unworkable
(The copied floppy shouldn't work).  
   For this I have constraint, I don't want to change the platform, which
reads this floppy.


The contents of the floppy could be anything like text file, exe file or
encrypted file.

Regards,
Pravin.


 

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25  5:37 Copy protection of the floppies Pravin Nanaware , Gurgaon
@ 2003-11-25  9:07 ` Murray J. Root
  2003-11-25  9:12 ` Måns Rullgård
                   ` (4 subsequent siblings)
  5 siblings, 0 replies; 16+ messages in thread
From: Murray J. Root @ 2003-11-25  9:07 UTC (permalink / raw)
  To: linux-kernel

On Tue, Nov 25, 2003 at 11:07:29AM +0530, Pravin Nanaware , Gurgaon wrote:
> Hi All,
> 
> 1> Could somebody suggest me the way to protect floppy from copying it's
> contents. 
> 2> If not possible, will it be possible to make the copied floppy unworkable
> (The copied floppy shouldn't work).  
>    For this I have constraint, I don't want to change the platform, which
> reads this floppy.
> 
> 
> The contents of the floppy could be anything like text file, exe file or
> encrypted file.

Encrypt the data. That's the only way that actually works. 

-- 
Murray J. Root


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25  5:37 Copy protection of the floppies Pravin Nanaware , Gurgaon
  2003-11-25  9:07 ` Murray J. Root
@ 2003-11-25  9:12 ` Måns Rullgård
  2003-11-25  9:28 ` YOSHIFUJI Hideaki / 吉藤英明
                   ` (3 subsequent siblings)
  5 siblings, 0 replies; 16+ messages in thread
From: Måns Rullgård @ 2003-11-25  9:12 UTC (permalink / raw)
  To: linux-kernel

"Pravin Nanaware , Gurgaon" <pnanaware@ggn.hcltech.com> writes:

> 1> Could somebody suggest me the way to protect floppy from copying it's
> contents. 

It's obviously impossible.

> 2> If not possible, will it be possible to make the copied floppy unworkable
> (The copied floppy shouldn't work).  

Equally impossible.

>    For this I have constraint, I don't want to change the platform, which
> reads this floppy.

In that case, you want to do the impossible.

-- 
Måns Rullgård
mru@kth.se


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25  5:37 Copy protection of the floppies Pravin Nanaware , Gurgaon
  2003-11-25  9:07 ` Murray J. Root
  2003-11-25  9:12 ` Måns Rullgård
@ 2003-11-25  9:28 ` YOSHIFUJI Hideaki / 吉藤英明
  2003-11-25  9:40   ` Måns Rullgård
  2003-11-25 10:47 ` Helge Hafting
                   ` (2 subsequent siblings)
  5 siblings, 1 reply; 16+ messages in thread
From: YOSHIFUJI Hideaki / 吉藤英明 @ 2003-11-25  9:28 UTC (permalink / raw)
  To: pnanaware; +Cc: linux-kernel, yoshfuji

In article <5F0021EEA434D511BE7300D0B7B6AB530CA67677@mail2.ggn.hcltech.com> (at Tue, 25 Nov 2003 11:07:29 +0530), "Pravin Nanaware , Gurgaon" <pnanaware@ggn.hcltech.com> says:

> 1> Could somebody suggest me the way to protect floppy from copying it's
> contents. 
> 2> If not possible, will it be possible to make the copied floppy unworkable
> (The copied floppy shouldn't work).  
>    For this I have constraint, I don't want to change the platform, which
> reads this floppy.

Basically, it depends on what kind of equipment you and the enemy have.
If you have special equipment and technique to write a floppy, you can make
a floppy which is not copiable by normal PCs.
But, if the enemy has similar equipment, he can do it.

About 15 years ago, there were many gaming softwares which were procected,
for example, by checking "gap" between sectors.  I also heard that there 
was a technique to change the hole of 5.25" (or 8") floppy for copy 
protection.

-- 
Hideaki YOSHIFUJI @ USAGI Project <yoshfuji@linux-ipv6.org>
GPG FP: 9022 65EB 1ECF 3AD1 0BDF  80D8 4807 F894 E062 0EEA

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25  9:28 ` YOSHIFUJI Hideaki / 吉藤英明
@ 2003-11-25  9:40   ` Måns Rullgård
  2003-11-25 10:55     ` Matthias Andree
  2003-11-25 16:07     ` Ricky Beam
  0 siblings, 2 replies; 16+ messages in thread
From: Måns Rullgård @ 2003-11-25  9:40 UTC (permalink / raw)
  To: linux-kernel

YOSHIFUJI Hideaki / .$B5HF#1QL@.(B <yoshfuji@linux-ipv6.org> writes:

> Basically, it depends on what kind of equipment you and the enemy
> have.  If you have special equipment and technique to write a
> floppy, you can make a floppy which is not copiable by normal PCs.
> But, if the enemy has similar equipment, he can do it.
>
> About 15 years ago, there were many gaming softwares which were procected,
> for example, by checking "gap" between sectors.

Can't that be done with a regular floppy drive and some special
software?

-- 
Måns Rullgård
mru@kth.se


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25  5:37 Copy protection of the floppies Pravin Nanaware , Gurgaon
                   ` (2 preceding siblings ...)
  2003-11-25  9:28 ` YOSHIFUJI Hideaki / 吉藤英明
@ 2003-11-25 10:47 ` Helge Hafting
  2003-11-25 20:18 ` Antonio Vargas
  2003-11-27  6:07 ` Willy Tarreau
  5 siblings, 0 replies; 16+ messages in thread
From: Helge Hafting @ 2003-11-25 10:47 UTC (permalink / raw)
  To: Pravin Nanaware , Gurgaon; +Cc: linux-kernel

Pravin Nanaware , Gurgaon wrote:
> Hi All,
> 
> 1> Could somebody suggest me the way to protect floppy from copying it's
> contents. 
> 2> If not possible, will it be possible to make the copied floppy unworkable
> (The copied floppy shouldn't work).  
>    For this I have constraint, I don't want to change the platform, which
> reads this floppy.
> 
> 
> The contents of the floppy could be anything like text file, exe file or
> encrypted file.
> 
Anything you can do others can do.  So this isn't really possible,
as many game vendors discovered in the 80's.  

What you can do, however, is to make a floppy that can't be copied using
the normal ways (cp, gui file manager) that _everybody_ knows how to use.

But it will always be possible for someone determined to copy your floppy,
and it only takes one "expert" copy onto a standard floppy or warez site
before everybody freely may copy the now unprotected stuff.

Floppy protection schemes usually only works for a floppy containing
a program, the idea is that the program checks that the floppy is
genuine and deliberately fails to decrypt contents if it isn't.

For example, the floppy may have some tracks formatted in a nonstandard way,
or some deliberately damaged sectors. (Program tries to write
to those ectors - if it works it knows it is an illegitimate copy.)

Ordinary copy programs can't copy this.  A sector copy program may
faithfully copy a disc sector with a bad checksum, but it won't make
the sector truely unwritable (i.e. scratched).

Experts can get around this in a number of ways though.
1. Study the original floppy and make a copy that is scratched in
   the right places.  Remember, they can do what you can do.
2. Disassemble the program and alter is so it skips the tests. This is
   a popular one.
3. Get the decrypted content from main memory by dumping 
   /dev/kmem or techniques similiar to that.

This makes such schemes unworkable for mass-market stuff, because
you'll quickly reach some hacker that see this as a challenge.
Once the "protection" is broken you have no secret any more.
Just like CSS . . .

Helge Hafting


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25  9:40   ` Måns Rullgård
@ 2003-11-25 10:55     ` Matthias Andree
  2003-11-25 16:07     ` Ricky Beam
  1 sibling, 0 replies; 16+ messages in thread
From: Matthias Andree @ 2003-11-25 10:55 UTC (permalink / raw)
  To: linux-kernel

On Tue, 25 Nov 2003, Måns Rullgård wrote:

> YOSHIFUJI Hideaki / .$B5HF#1QL@.(B <yoshfuji@linux-ipv6.org> writes:
> 
> > Basically, it depends on what kind of equipment you and the enemy
> > have.  If you have special equipment and technique to write a
> > floppy, you can make a floppy which is not copiable by normal PCs.
> > But, if the enemy has similar equipment, he can do it.
> >
> > About 15 years ago, there were many gaming softwares which were procected,
> > for example, by checking "gap" between sectors.
> 
> Can't that be done with a regular floppy drive and some special
> software?

It depends. Checking gap length (exactly) and location of one track
relative to the next would require drives with synchronized spindles to
copy the data iff the gap information is used as encryption key. Whether
Linux is up to the task, is something different. Last time I tried such
a thing was in the good old Commodore 1541 days which also supported
half-steps between tracks and stepping after 1/3rd track or some things.

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25  9:40   ` Måns Rullgård
  2003-11-25 10:55     ` Matthias Andree
@ 2003-11-25 16:07     ` Ricky Beam
  2003-11-25 18:37       ` Nick
  1 sibling, 1 reply; 16+ messages in thread
From: Ricky Beam @ 2003-11-25 16:07 UTC (permalink / raw)
  To: Måns Rullgård; +Cc: linux-kernel

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: TEXT/PLAIN; charset=X-UNKNOWN, Size: 947 bytes --]

On Tue, 25 Nov 2003, [iso-8859-1] Måns Rullgård wrote:
>> About 15 years ago, there were many gaming softwares which were procected,
(it was more than 15 years ago.)
>> for example, by checking "gap" between sectors.
>
>Can't that be done with a regular floppy drive and some special
>software?

Please heed the lessons already learned in the software industry...
Copy protection doesn't work.  It works about as well as locks on doors
as it'll keep the honest people honest, and offer a small obstacle to
the dishonest.

As others have stated, anything *you* can do with a PC floppy drive, *I*
can do. (And given this thread, I can probablly do a few things you
currently cannot.)  Ultimately, any copy protection comes down to
the software on the floppy.  If the machine can read it to execute it,
the hacker can read it to remove the checks.  No ammount of hand-waving
will change that. (That, btw, is why the DMCA, et. al., exist.)

--Ricky



^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25 16:07     ` Ricky Beam
@ 2003-11-25 18:37       ` Nick
  2003-11-25 20:07         ` Richard B. Johnson
                           ` (2 more replies)
  0 siblings, 3 replies; 16+ messages in thread
From: Nick @ 2003-11-25 18:37 UTC (permalink / raw)
  To: Ricky Beam; +Cc: Måns Rullgård, linux-kernel

Hardware dongles.  You need to be a bit creative but it can be done.  Say
on save of the file output it to the hardware dongle with encrypts it with
your private key, then on load of the file it gets decrypted with the
public key, which is available, or some similar scheme.
	Nick

On Tue, 25 Nov 2003, Ricky Beam wrote:

> On Tue, 25 Nov 2003, [iso-8859-1] Måns Rullgård wrote:
> >> About 15 years ago, there were many gaming softwares which were procected,
> (it was more than 15 years ago.)
> >> for example, by checking "gap" between sectors.
> >
> >Can't that be done with a regular floppy drive and some special
> >software?
> 
> Please heed the lessons already learned in the software industry...
> Copy protection doesn't work.  It works about as well as locks on doors
> as it'll keep the honest people honest, and offer a small obstacle to
> the dishonest.
> 
> As others have stated, anything *you* can do with a PC floppy drive, *I*
> can do. (And given this thread, I can probablly do a few things you
> currently cannot.)  Ultimately, any copy protection comes down to
> the software on the floppy.  If the machine can read it to execute it,
> the hacker can read it to remove the checks.  No ammount of hand-waving
> will change that. (That, btw, is why the DMCA, et. al., exist.)
> 
> --Ricky
> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25 18:37       ` Nick
@ 2003-11-25 20:07         ` Richard B. Johnson
  2003-11-25 20:52         ` Ricky Beam
  2003-11-26  3:55         ` Gene Heskett
  2 siblings, 0 replies; 16+ messages in thread
From: Richard B. Johnson @ 2003-11-25 20:07 UTC (permalink / raw)
  To: Nick; +Cc: Ricky Beam, M�ns Rullg�rd, Linux kernel

On Tue, 25 Nov 2003, Nick wrote:

> Hardware dongles.  You need to be a bit creative but it can be done.  Say
> on save of the file output it to the hardware dongle with encrypts it with
> your private key, then on load of the file it gets decrypted with the
> public key, which is available, or some similar scheme.
> 	Nick
>

Dongles all use the same scheme! This means that if you've made
one program that uses a dongle, you can certainly emulate it!


> On Tue, 25 Nov 2003, Ricky Beam wrote:
>
> > On Tue, 25 Nov 2003, [iso-8859-1] Måns Rullgård wrote:
> > >> About 15 years ago, there were many gaming softwares which were procected,
> > (it was more than 15 years ago.)
> > >> for example, by checking "gap" between sectors.
> > >
> > >Can't that be done with a regular floppy drive and some special
> > >software?
> >
> > Please heed the lessons already learned in the software industry...
> > Copy protection doesn't work.  It works about as well as locks on doors
> > as it'll keep the honest people honest, and offer a small obstacle to
> > the dishonest.
> >

It'll keep honest people pissed and others entertained. In the
DOS days, there were holes burned into the floppies in certain
sectors. This kept diskcopy and other DOS stuff from copying
the floppies.  I just made a TSR that emulated the burnt holes
for the application and a copy routine that didn't care about
bad sectors (it ignored them).

The result was that you didn't need a "key" disk in drive A:
anymore. To the user, you just executed the program.

> > can do. (And given this thread, I can probablly do a few things you
> > currently cannot.)  Ultimately, any copy protection comes down to
> > the software on the floppy.  If the machine can read it to execute it,
> > the hacker can read it to remove the checks.  No ammount of hand-waving
> > will change that. (That, btw, is why the DMCA, et. al., exist.)
> >
> > --Ricky
> >

Cheers,
Dick Johnson
Penguin : Linux version 2.4.22 on an i686 machine (797.90 BogoMips).
            Note 96.31% of all statistics are fiction.



^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25  5:37 Copy protection of the floppies Pravin Nanaware , Gurgaon
                   ` (3 preceding siblings ...)
  2003-11-25 10:47 ` Helge Hafting
@ 2003-11-25 20:18 ` Antonio Vargas
  2003-11-25 20:32   ` Måns Rullgård
  2003-11-27  6:07 ` Willy Tarreau
  5 siblings, 1 reply; 16+ messages in thread
From: Antonio Vargas @ 2003-11-25 20:18 UTC (permalink / raw)
  To: Pravin Nanaware , Gurgaon; +Cc: linux-kernel

On Tue, Nov 25, 2003 at 11:07:29AM +0530, Pravin Nanaware , Gurgaon wrote:
> Hi All,
> 
> 1> Could somebody suggest me the way to protect floppy from copying it's
> contents. 
> 2> If not possible, will it be possible to make the copied floppy unworkable
> (The copied floppy shouldn't work).  
>    For this I have constraint, I don't want to change the platform, which
> reads this floppy.
> 
> 
> The contents of the floppy could be anything like text file, exe file or
> encrypted file.
> 
> Regards,
> Pravin.

Usual PC floppy controllers are not very flexible, so you just need
some more-flexible controller to do the trick. A popular choice
for creating master disks is to get an Amiga with an 1.44 floppy
(any A4000 will do), make some scratched disks and then duplicate
them with some fine 1990-ish hardware disk copier.


-- 
winden/network

1. Dado un programa, siempre tiene al menos un fallo.
2. Dadas varias lineas de codigo, siempre se pueden acortar a menos lineas.
3. Por induccion, todos los programas se pueden
   reducir a una linea que no funciona.

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25 20:18 ` Antonio Vargas
@ 2003-11-25 20:32   ` Måns Rullgård
  2003-11-26  3:58     ` Gene Heskett
  0 siblings, 1 reply; 16+ messages in thread
From: Måns Rullgård @ 2003-11-25 20:32 UTC (permalink / raw)
  To: linux-kernel

Antonio Vargas <wind@cocodriloo.com> writes:

> Usual PC floppy controllers are not very flexible, so you just need
> some more-flexible controller to do the trick. A popular choice
> for creating master disks is to get an Amiga with an 1.44 floppy
> (any A4000 will do), make some scratched disks and then duplicate
> them with some fine 1990-ish hardware disk copier.

If I'd like to copy those disks, I'd just have to dig out the old
Amiga, right?

-- 
Måns Rullgård
mru@kth.se


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25 18:37       ` Nick
  2003-11-25 20:07         ` Richard B. Johnson
@ 2003-11-25 20:52         ` Ricky Beam
  2003-11-26  3:55         ` Gene Heskett
  2 siblings, 0 replies; 16+ messages in thread
From: Ricky Beam @ 2003-11-25 20:52 UTC (permalink / raw)
  To: Nick; +Cc: Linux Kernel Mail List

On Tue, 25 Nov 2003, Nick wrote:
>Hardware dongles.  You need to be a bit creative but it can be done.  Say
>on save of the file output it to the hardware dongle with encrypts it with
>your private key, then on load of the file it gets decrypted with the
>public key, which is available, or some similar scheme.

SOFTWARE still has to talk to the dongle.  SOFTWARE can be CHANGED.  Go
talk to the guys at autocad... it's trivial to find TSRs to emulate
the dongle and patches to out-right do away with it.

--Ricky



^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25 18:37       ` Nick
  2003-11-25 20:07         ` Richard B. Johnson
  2003-11-25 20:52         ` Ricky Beam
@ 2003-11-26  3:55         ` Gene Heskett
  2 siblings, 0 replies; 16+ messages in thread
From: Gene Heskett @ 2003-11-26  3:55 UTC (permalink / raw)
  To: Nick, Ricky Beam; +Cc: Måns Rullgård, linux-kernel

On Tuesday 25 November 2003 13:37, Nick wrote:
>Hardware dongles.  You need to be a bit creative but it can be done.
>  Say on save of the file output it to the hardware dongle with
> encrypts it with your private key, then on load of the file it gets
> decrypted with the public key, which is available, or some similar
> scheme.
>	Nick

This "thread" has finally pulled my trigger, rant mode on.

Fugedaboutit.  The last piece of dongle protected software I tangled 
with was an A-B Roll video editor for the amiga.  The life of the 
parallel port dongle was about 9 months because they damaged the 
chips in it so badly in grinding off the identifications.

When the 3rd dongle died, and we found the outfit had been sold to 
somebody else, and it was discovered they didn't have any more 
dongles, and furthermore they weren't even sure we had rights to the 
fscking software!  We screwed around with them for about 6 months and 
I finally gave them the choice of seeing us in court or finding a 
dongle.  They got in the car and drove something like 400 miles one 
way to get the last dongle in existance off the authors home machine 
and sent it to us overnight.  They must have finally gotten the 
message that we were at the breaking point of being pissed and 
somebody was gonna bleed.

Frankly, we felt as if we had the right to make somebody bleed, color 
(red or green) optional since the software was part of a $25,000 
dollar video editing package (that wasn't the video tape recorders, 
just the software and networking hardware, we had another $50,000 in 
broadcast quality VCR's in that system) that we had paid around $2000 
just for updates of since we'ed bought it 2 years before this little 
rodeo started.

In the meantime we finally made good on our threat to send it out to 
the hackers (we told them that was one of our options and I think 
thats what got them to put the key in the switch and drive), and had 
a clean, no dongle required, version of it back in about 36 hours.  
And believe it or not, there is honor among the hackers who broke 
that for us, no copy was ever released into the wild.  And they did 
it just to prove they could, no charge folks!  Sometime later yet, 
they (RVS) wanted a copy of the one we had broken.  I left it to 
TPTB, but I think they were told to go pound sand just for being the 
ass-holes they had proved themselves to be.

Do you want to put your 'clients' thru that?  I think not if you want 
to sleep well at night.

We, as users, are normally pretty honest.  We screwed around with 
those jokers at RVS for 6 months before we did what we had to do, and 
I think that was 5 months and 23 days too long considering it was the 
production heart of a television station at the time.  That lack of a 
dongle for 6 months cost us about $125,000 in lost production 
revenues because our main editing suite was down.

It boils down to trusting your clients.  Most of us, if we need your 
software to do something that cannot be done any other way, will be 
glad to honor your rights to that software as long as it is actively 
supported even if its do almost nothing updates just to keep the cash 
cow coming fresh.  We fully understand that one needs a 'stream' of 
revenue for long term support.

OTOH, if the support goes away because you who originally asked the 
question no longer have a quarter to call somebody who cares, and its 
still the only thing that does that job, and your so-called 
protection methods get in the way, then you can fully expect that 
they will be rendered null and void.  Call it piracy, whatever, 
welcome to how the real world works. class 101.

Bottom line is treat us right, we'll treat you right.

End of rant...

[...]

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.27% setiathome rank, not too shabby for a WV hillbilly
Yahoo.com attornies please note, additions to this message
by Gene Heskett are:
Copyright 2003 by Maurice Eugene Heskett, all rights reserved.


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25 20:32   ` Måns Rullgård
@ 2003-11-26  3:58     ` Gene Heskett
  0 siblings, 0 replies; 16+ messages in thread
From: Gene Heskett @ 2003-11-26  3:58 UTC (permalink / raw)
  To: Måns Rullgård, linux-kernel

On Tuesday 25 November 2003 15:32, Måns Rullgård wrote:
>Antonio Vargas <wind@cocodriloo.com> writes:
>> Usual PC floppy controllers are not very flexible, so you just
>> need some more-flexible controller to do the trick. A popular
>> choice for creating master disks is to get an Amiga with an 1.44
>> floppy (any A4000 will do), make some scratched disks and then
>> duplicate them with some fine 1990-ish hardware disk copier.
>
>If I'd like to copy those disks, I'd just have to dig out the old
>Amiga, right?

Yup, it has the magic twanger built right in.

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.27% setiathome rank, not too shabby for a WV hillbilly
Yahoo.com attornies please note, additions to this message
by Gene Heskett are:
Copyright 2003 by Maurice Eugene Heskett, all rights reserved.


^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: Copy protection of the floppies
  2003-11-25  5:37 Copy protection of the floppies Pravin Nanaware , Gurgaon
                   ` (4 preceding siblings ...)
  2003-11-25 20:18 ` Antonio Vargas
@ 2003-11-27  6:07 ` Willy Tarreau
  5 siblings, 0 replies; 16+ messages in thread
From: Willy Tarreau @ 2003-11-27  6:07 UTC (permalink / raw)
  To: Pravin Nanaware , Gurgaon; +Cc: linux-kernel

Hi,

I don't believe in copy protection at all because what your program can read,
other programs can read, and what your program can test, others can trick it
into not testing it anymore.

However, there was a solution that I found clever : the weak bit. Basically,
a floppy was written with a special controller, and one sector had invalid
states that could randomly be read either 0 or 1 by the drive. The software
then tried to read the same sector 10 times and expected the contents to
change due to the controller's inability to identify the data as clear 0 or 1.
A copy of the floppy would definitely fix the contents to what was read at the
copy time, so the software would not see any more changes during its read test
and would conclude that it was a copy.

I'm not certain that this was fully compatible with all drives and/or
controllers, because there's always a risk of some hardware always reporting
0's or 1's on this sector, but I found the concept original.

Of course, it took the editor far more time to develop this solution than the
crackers to "fix" the software. You know, launch debug, replace the offending
JZ with a JMP or with a NOP/NOP...

Sincerely, I don't think you want to spend so much time developping something
which can be broken within a few minutes.

Regards,
Willy


^ permalink raw reply	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2003-11-27  6:07 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2003-11-25  5:37 Copy protection of the floppies Pravin Nanaware , Gurgaon
2003-11-25  9:07 ` Murray J. Root
2003-11-25  9:12 ` Måns Rullgård
2003-11-25  9:28 ` YOSHIFUJI Hideaki / 吉藤英明
2003-11-25  9:40   ` Måns Rullgård
2003-11-25 10:55     ` Matthias Andree
2003-11-25 16:07     ` Ricky Beam
2003-11-25 18:37       ` Nick
2003-11-25 20:07         ` Richard B. Johnson
2003-11-25 20:52         ` Ricky Beam
2003-11-26  3:55         ` Gene Heskett
2003-11-25 10:47 ` Helge Hafting
2003-11-25 20:18 ` Antonio Vargas
2003-11-25 20:32   ` Måns Rullgård
2003-11-26  3:58     ` Gene Heskett
2003-11-27  6:07 ` Willy Tarreau

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