need help with map files/game variant files

[D4rkn1c0n]

i am trying to make my own program to edit halo 2 maps for systems more than just window i am making one that will edit game variant files and save profiles and the maps but all i can find is information on the format of the files i cant find anyone that can tell me the encription methods, compression methods, checksum calculations, or how to sign the maps if anyone can help me i will gladly give some credit to you for helping thanks.