wtbw
September 17th, 2007, 15:20
Hey guys, thanks for the congrats, but it was a team effort
It turned out to be standard HMAC SHA-1, with a complicated key generation based on the FireWireGUID (unique for each iPod).. perhaps that's some standard function too (involving LCM and a couple of lookup tables to expand to 16 bytes and then SHA-1ing) but it wasn't something I recognized.
There was a lot of arithmetic obfuscation in it too; ollydbg traces logs were very helpful (and probably faster than coding a proper deobfuscator, though less reusable if they change it all...).
Just a fun weekend...
