Here are the tools for playing with iOS firmwares.
xpwntool: Firmware decryption utility
dmg: RootFS decryption utility
irecovery: Tools for sending iBSS and iBEC to device, and communicating with device in DFU mode
iBoot32Patcher: Patch iBoot (iBSS and iBEC) out of signature checks
sshtool: SSH connection utility
image3maker: Create img3 image for booting
reimagine: Almost the same as xpwntool, but with higher reliablity.