Hacking Thought on making the downloads smaller

[IBNobody]

I agree it's a really dirty method

I was thinking about that as I got up this morning.

What I am now going to do though is a minor tweak to the code (v1.1) that will replace the data not with 0xFFs but with a valid sector from the ISO being read. That way the sector header will not be so easy to detect in a scrubbed disc.

The other alternative is to keep the sector headers 0x400 bytes and blank the rest 0x7c00.

What I would suggest at the moment is that a difference file is created between the two ISOs (in and out) so that there is always the option of recreating the original ISO if there is a problem (that would be a 2 rar set release though - 1 = scrubbed image, 2 = diff file). The Diff file would effectively contain only the 'garbage' but should compress to 4.5G - whatever the scrubbed one contained as data.

How much will these changes affect the compression ratio?

 

[Flawsdraw]

well a game compressed from 4.37GB to 4.14GB ended up being at 444MB compressed, so the compression ratio is pretty damn good

 

[73ARM3]

Great app Dack, just done telly addicts and it goes down to 151mb.

 

[klyick]

How much will these changes affect the compression ratio?

As I understand it, not much. It looks like he is taking a encrypted sector, not sure if it is random, and copying it over all non data sectors.(please correct me if I am wrong.)

So, if that was the case, I would imagine that the repeating data i.e. that one encrypted sector would be very compression friendly.

 

[IBNobody]

How much will these changes affect the compression ratio?


As I understand it, not much. It looks like he is taking a encrypted sector, not sure if it is random, and copying it over all non data sectors.(please correct me if I am wrong.)

So, if that was the case, I would imagine that the repeating data i.e. that one encrypted sector would be very compression friendly.

What is the size of a Wii sector? 512 bytes? I could see compression gains from that.

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Also, I wanted to share my viewpoint on whether or not this is detectable.

I personally think that it is. However, I'm not too worried about it.

Nintendo has two strategies they can use to catch people running scrubbed ISOs. This assumes they do ANYTHING, which I highly doubt. They're more likely to try things that catch all ISOs, not just scrubbed ones.

Here are their strategies.
1. They can write code into a game that checks the garbage sectors.
2. They can write firmware code that checks the garbage sectors.

If they try #1, we just won't scrub that ISO.
If they try #2, we just won't upgrade firmware. (You shouldn't be upgrading firmware anyway!)

I plan on holding off scrubbing all my files until Dack has all the kinks worked out. But once it happens... Look out!

 

[PSXDupe]

Or option #3

They could also put a couple of dummy files on the disc which fills the disc up.

These files would then be seen as used data, they would also be encrypted and
Wii Scrubber would not make any difference to the ISO compression at all.

 

[IBNobody]

Or option #3

They could also put a couple of dummy files on the disc which fills the disc up.

These files would then be seen as used data, they would also be encrypted and
Wii Scrubber would not make any difference to the ISO compression at all.

Why would they bother stopping you from scrubbing your ISOs? What would they gain? Would they stop downloads? No. People are already downloading 4.5GB piles of shovelware shit.

They'd put more emphasis into blocking ISOs (scrubbed and unscrubbed) from running than from being vindictive.

If they were to put large filler files into the image, though, they'd have to be random garbage in order to prevent compression. (Puzzle Quest had large 1GB empty files, and the pre-scrubbed ISO shrank to ~250MB)

 

[PSXDupe]

Agreed, but it is an option.

I have just tried

Sonic Riders - Zero Gravity (PAL)
Jenga (PAL)

Both work fine, no problems.

 

[IBNobody]

Dack,

Would you consider adding in automatic compression using the freeware 7z or Zlib libraries?

 

[Salamantis]

Also if you could make a Mac version that would be great...

Nice app anyways!

 

[Dack]

Mac users

Actually don't think I won't get much time to play with code over the next few weeks - lots of personal stuff going on

As a result here's the link to the source code.

http://rapidshare.com/files/94076138/WIISc...SOURCE.rar.html

This is on the condition that no-one takes the urine out of my bad coding 'style'.

People can do with the code whatever they wish - I've commented quite a bit of it and shamelessly stole lots of other bits (the tree stuff can definately go - it's a hangover from the wiifuse software).

Thoughts for improvements:
1. Add a brick block option - I was thinking of a 3 option there, 1=Keep partition, 2 = brick block partition, 3 = delete update partition.
2. Allow for over-ride of sectors marked as blank - this would allow future protections to potentially be circumvented
3. Include on the fly compression option (or at least external command i.e. at end of save fire the rar compresson)
4. Create a diff file so that if ever needed the complete image could be reconstructed
5. Find out what went wrong with wiifit (though I wonder if the compressed rar was burned to the disc. As the first 0x40000 and partition datas are always kept it shouldn't have generated an 'unknown disc' error)
6. Change the icon to a thing of beauty

Have fun

edit: almost forgot - I kept in the Gamecube bits but hard coded a few areas for the WII . With minor tweaking it should be able to play with the Gamecube discs too.

 

[niklasnyfiken]

Dack,

Would you consider adding in automatic compression using the freeware 7z or Zlib libraries?

Sooner or later someone is going to want it to cook for us also. Write a simple batch file to compress the wiped ISO.

 

[Rebound]

Great app, I wish I could help, but since I don't know anything about programming I just decided to make an icon that you could sue fr the scrubber

If you like it you can download the .ico file here http://rapidshare.com/files/94111489/dsadsa.ico.html

 

[stormyuan]

5. Find out what went wrong with wiifit (though I wonder if the compressed rar was burned to the disc. As the first 0x40000 and partition datas are always kept it shouldn't have generated an 'unknown disc' error)

Hi,Dack

I double checked WiiFit again ,
and it worked fine with both wiiscrubber1.0 and 1.0a

I'm sorry about my report yesterday.
Thanks for you great work!

 

[Dack]

Thanks for letting me know, out of interest what size did it go down to?

 

[stormyuan]

Dear Sir,
WiiFit(jp version) - fit ^^;
capacity of ISO data & RAR(fastest compressed) data

with 1.0 + rar(fastest compress) about 670MB
with 1.0a + rar (fastest compress) about 780MB

 

[Dack]

Thats interesting to see - the reason for the 1.0a being bigger is because of the sector headers being kept. So basically it's about 110Meg more for 3.6 gig of scrubbed data.

 

[PSXDupe]

Still knocks the shite out of 4.5gb

 

[73ARM3]

So far, my ISO`s are all compressing to 151mb, is that right?

Telly Addicts - 4.37 GB (4,699,979,776 bytes)
Scrubbed and compressed - 151 MB (158,663,998 bytes)

PDC Darts - 4.37 GB (4,699,979,776 bytes)
Scrubbed and compressed - 151 MB (159,051,708 bytes)

Winter sports - 4.37 GB (4,699,979,776 bytes)
Scrubbed and compressed - 151 MB (159,080,361 bytes)

Is this just a lucky coincidence?

 

[Dack]

So far, my ISO`s are all compressing to 151mb, is that right?

Telly Addicts - 4.37 GB (4,699,979,776 bytes)
Scrubbed and compressed - 151 MB (158,663,998 bytes)

PDC Darts - 4.37 GB (4,699,979,776 bytes)
Scrubbed and compressed - 151 MB (159,051,708 bytes)

Winter sports - 4.37 GB (4,699,979,776 bytes)
Scrubbed and compressed - 151 MB (159,080,361 bytes)

Is this just a lucky coincidence?

looks like it

The actual file sizes themselves are different.

When you load the iso into the scrubber software - what size does it say in the top right - thats usually a pretty good indication.