Differences between EDC/Anti-modchip/LibCrypt?

Post by **kiffy** » April 19th, 2024, 7:56 pm

According to redump.org they are not the same, I thought Anti-modchip is the same with LibCrypt and stored in .SBI format?

Post by **nocash** » April 19th, 2024, 11:21 pm

EDC's are CRC32's inside of the 930h-byte data sectors.
Libcrypt uses bad CRC16's in the sub-channels, that require a .SBI or .SUB file (or other sub-channel dumps).

Post by **kiffy** » April 19th, 2024, 11:55 pm

nocash wrote: ↑April 19th, 2024, 11:21 pm Libcrypt uses bad CRC16's in the sub-channels, that require a .SBI or .SUB file (or other sub-channel dumps).

Thank you nocash.

Is Anti-modchip and LibCrypt the same?

In redump.org they differentiate it. LibCrypt aren't implemented in any PSX demo disc while Anti-modchip is implemented in some PSX demo disc.

Post by **nocash** » April 21st, 2024, 11:26 am

Anti-modchip is yet something else:
A modchip does simulate the SCEX wobble (which SHOULD only occur in Lead-In area, but many early modchips do simulate that SCEX signal everywhere including in the discs data area).
Anti-modchip protections do check that SCEX does occur ONLY in Lead-In area.

Post by **kiffy** » April 21st, 2024, 11:35 am

Thank you.