DATA.BIN Encryption

The DATA.BIN file on the Monster Hunter UMDs contains all of the quests, graphics, musics, dialog, etc. It's partially encrypted and seems to use the same encryption table for every Monster Hunter game.

##Table of Contents The DATA.BIN is a sort of archive which starts out with an encrypted table of contents for the files it contains which is split into two sections. The first section is a list of 2048 byte block offsets for the start of each file inside the DATA.BIN archive. The second section is a list of the sizes of each file that is not encrypted.

##Decryption To decrypt a section of the DATA.BIN you must start at the beginning of a 2048 byte block and initialize the key with the block number. Each encrypted section is a certain number of blocks and if the file is not a multiple of 2048 bytes it is padded with a predetermined sequence of bytes.

##Location of functions in Monster Hunter Portable 3rd I found these function using PSPLink by putting a break point on sceIoRead and following the code. The decryption function can be found at 0x0886278C and the key initialization function can be found at 0x0886233C in memory.