Viktigt meddelande

**Swizzy** · 2010-10-27, 20:26

Det är inte omöjligt, men det lär inte ta lång tid innan man löser det problemet också

**Pendragon** · 2010-10-28, 08:55

Jag har en lösning

Just nu är den prissatt till 2.849 kr

Spoiler: En 360 Slim med Fable 3 bundlat *Omoddat o 100% Livesäkert*

*Ja jag vet att jag har dålig humor men jag har varit uppe sen 05:00 o sitter just nu o hinkar en Cherry Coke

**samplehead** · 2010-10-30, 12:22

Det finns som sagt en hel del rykten om vad det nya skyddet är och hur det fungerar. Hittade en förklaring som lät mer trovärdig än andra. Om det visar sig vara sant lär det bli betydligt svårare med backups i framtiden. Tiden får utvisa.

QUOTE
When a disk is inserted, the drive itself measures timing and sector alignement over a PSN range specified in the SS.
These are the CHALLENGES.

The "protected" area of the disk, contains malformed/impossible to create geometries, sectors, and or data.

The drives FW, using the PSN ranges and type entries in the SS, measures performance of reading these areas.

Among the things checked:
Sector to sector physical alignemnt.
Seek performance time measurements across areas with "bad" sectors.
Actual data from the "bad" sectors.

The SS only conatins 0x21 entries or so, and the extreme SS simply has those 0x21 answers stored there.
During "ripping" the drive is asked each of the 0x21 challenges, the drive uses the original fw to calculate the responses, and stores the answers in the extreme SS. The extreme FW merely looks up the correct "response" from its stored response list to each challenge the drive sees. It can only proved a correct response for the 0x21 challenges it knows the answers for.

With an original disk the drive doesnt just look up some hard coded answer, it uses the table of 0x21 psn ranges to inspect the protected area to CALCULATE the response.

What is ap25?

A database of challenges (psn ranges) that are not stored in disk SS. They are downloaded. The drive will use these "downloaded" psn ranges, to perform the measurements descibed above. The extreme SS cant respond correctly, it only the knows the few challenges stored on the disk itself. Since the responses are calculated by these measurements, and the measurement parameters (psn ranges) are downloadable from live, you can see it quickly becomes very hard to store all the responses, mainly cause you dont know what the challenge will be. The number of challenges has now gone from only 0x21 or so to nearly infinite. If you have the real disk, the drives fw can respond correctly to any of them, by actually measuring the media itself.
Read that, especially the bolded. You might want to read it twice.

Here's the issue which Tiros is addressing--or at least my basic understanding of it: iXtreme stores challenge responses in the drive's memory. There were a very limited set of challenge parameters which were calculated based on the disc SS, so it was easy to store in drive memory. However, AP25 can use new parameters downloadable from LIVE (or, presumably, other methods, like a dashboard update). Since these can change constantly by Microsoft updating the system (and given that values are not inherently limited as Microsoft has a free choice of the values themselves as well as their number), there are essentially an infinite number of challenge parameters that can be used.

Burned discs won't respond correctly to these challenges; storing all of the challenges in the firmware itself is not possible as there are an unlimited amount of possible challenges. This results in burned discs failing AP25 checks. Therein lies the "problem".