There’s a new firmware tool out. Stefan Esser (@i0n1c) recently released xpwntool-lite. It is GPLv3-licensed, and written in C, for a Unix/GCC build environment. This fork is based on the PlanetBeing xpwn tool.
“Xpwntool-light is a lightweight version of xpwntool just for decrypting IMG3 firmware files. This is a stripped down version of xpwntool from xwpn. We ripped out a lot of stuff that is not required for simple xpwntool usage in order to decrypt IMG3 files that ship with iOS firmwares.”
usage: xpwntool-light <infile> <outfile> [-t <template> [-c <certificate>]] [-k <key>] [-iv <key>] [-decrypt]