&quot;To do some work to make it universal&quot; = code change = thrown hash (the signature which requires the Apple key to create, and proves the software hasn&#x27;t been tampered with, will be broken&#x2F;no longer valid)<p>Cryptographic hashes like SHA and AES are designed for &quot;dispersion&quot; meaning, in the idea case, flipping only one bit of the input leads to a 50% probability of <i>every single bit</i> in the hash flipping. So while it&#x27;s theoretically possible to make a change to the code, and find a way to insert that change that both (1) does the same thing and (2) hashes the same way as the original build, it&#x27;s probably beyond the realm of what even a motivated attacker could do today.