Technically, yes. But there’s a catch: Apple’s cryptographic signing process . If you change even one byte, the file will no longer be valid for a standard restore on modern devices. Technically, yes
If you just want to customize iOS, look into or Dopamine / palera1n — they modify the running OS without permanently altering the IPSW. If you just want to customize iOS, look
Ever wanted to peek inside Apple’s firmware? Modifying an IPSW file is the first step to custom iOS. Here’s exactly how to unpack, tweak, and repack the file—and the security roadblocks you’ll face. Introduction The .ipsw file (iPhone Software) is the lifeblood of every iPhone, iPad, and iPod touch. It’s the firmware package Apple uses to restore, update, or reinstall iOS. For the average user, it’s a black box. But for security researchers, jailbreak developers, and tinkerers, it’s a treasure trove.
If you modify the IPSW without also exploiting the (A5–A11 chips, iPhone 4s–X), the restore will fail with error 3194 or -1 .
The Deep Dive: How to Modify an IPSW File (And Why You Probably Shouldn’t)