LLB

This is the Low Level Bootloader. It runs several setup routines and on firmware versions 2.0 and higher it checks the signature of iBoot before jumping to it.

Those same setup routines are present in iBEC and iBSS, which is why they can be launched directly from DFU Mode.

Patched LLB
Restoring or flashing an LLB patched with Pwnage or 0x24000 Segment Overflow can lead to these changes:
 * ECID checks on boot-up are cancelled
 * A restored firmware is no longer integrity-checked
 * RSA Signature Hash blobs (SHSH) and APTicket are ignored
 * Jailbreak is always untethered for a pwn-able device
 * Custom boot logos and recovery logos can be applied