Kingsoft Protection - Revision history

Enigma at 00:30, 17 April 2021

2021-04-17T00:30:38Z

Enigma at 22:03, 13 April 2021

2021-04-13T22:03:54Z

Enigma at 21:47, 13 April 2021

2021-04-13T21:47:21Z

Enigma at 17:26, 13 April 2021

2021-04-13T17:26:38Z

Enigma at 10:08, 13 April 2021

2021-04-13T10:08:53Z

Enigma at 10:06, 13 April 2021

2021-04-13T10:06:15Z

Enigma: Created page with "Descriptions needs to be done. ==== Pages that refer to this protection ==== {{Special:Whatlinkshere/Kingsoft Protection}}"

2021-04-13T09:28:25Z

Created page with "Descriptions needs to be done. ==== Pages that refer to this protection ==== {{Special:Whatlinkshere/Kingsoft Protection}}"

New page

Descriptions needs to be done.

==== Pages that refer to this protection ====

{{Special:Whatlinkshere/Kingsoft Protection}}

← Older revision		Revision as of 00:30, 17 April 2021
Line 58:		Line 58:
	whereas this is the actual read data.		whereas this is the actual read data.

−	Of course this only works because we map here the faster clocked speed zone 3 to the slower clocked speed zone 0.	+	Of course this only works because we map here the faster clocked speed zone 3 to the slower clocked speed zone 0. Please note that the speed zone 3 byte pattern can as well be different and still decode to the correct GCRs at speed zone 0.

@@ Line 8: / Line 8: @@
 [[File:quiwi_flux_plot.png|thumb|Flux plot of track 1]]
-Track 1 Sector 20 decoded at speed zone 3. Notice the wrong data block.
+Track 1 Sector 20 decoded at speed zone 3. Notice the data block area that is incorrect with decoding at speed zone 3.
     sync 31
     ; header

@@ Line 48: / Line 48: @@
 This signature is the same for Side 0 and Side 1 of [[Quiwi]].
-==== The Emulator G64 Speed Zone Problem ====
+==== The Emulator G64 'Variable Speed Zone on the same track' Problem ====
-Now another problem comes up. When using G64 as image format the tracks speed is purely determined by the track length in bytes in the emulators. The track length rotates virtually every 200ms and is decoded once more with the set speed zone. Thus, this simplification of the G64 format prevents putting sectors with different speed zones into a track in the G64.
+When using G64 as image format the tracks speed is purely determined by the track length in bytes in the emulators. The emulator rotates the track data virtually every 200ms. It is decoded again with the set speed zone. Thus, a previously decoded flux based stream with speed zone 3 is identical in the emulator when it is again decoded at a speed zone 3 setting. For this specific case we have the advantage that speed zone 3 uses a faster clock than speed zone 0 that we need for sector 20. Thus, if the track length of track 1 corresponds to speed zone 3 (default) and sector 20 is present as if the actual speed zone 0 data is encoded at speed 3 then in emulation set at speed zone 0 the data should be decoded with GCRs c4 48 ... etc.
-Now specifically for this protection a trick can be exploited. In the D64 emulation the speed zone setting is basically ignored as only the data is read. Thus, after the 127 GCRs signature, that consists of valid GCRs the sector can simply be filled with any data. As the protection check ignores the checksum, we can set a valid data block checksum as well and get an error free D64.
+So we save as track data in speed zone 3:
 Thus for our D64 only:
@@ Line 67: / Line 76: @@
     gcr 0f
     bytes 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 57
 ==== Pages that refer to this protection ====
 {{Special:Whatlinkshere/Kingsoft Protection}}

@@ Line 34: / Line 34: @@
     bits 1
-Just the data block decoded at speed zone 0 returns a block with a correct start and correct GCR 07 as data block id:
+The same data block decoded at speed zone 0 returns a block with a correct start and correct GCR 07 as data block id:
     sync 31
     ; data

@@ Line 1: / Line 1: @@
-Descriptions needs to be done.
+This protection appears on various games by Kingsoft.
 ==== Pages that refer to this protection ====
 {{Special:Whatlinkshere/Kingsoft Protection}}