@julian So why does 8b32 allow for dropping the HTTP signature? My best guess is that the wording is vague and the intention is that an object integrity proof at top level means an HTTP signature can be discarded. You're right, the sentence was poorly written. It was meant to apply to top-level proofs only. I'll update the FEP. I know of no situation where an AP-compliant server POSTs another server without an HTTP Signature. Pretty sure any attempt to do so would just mean the activity is dropped. Mitra would accept an activity with integrity proof if HTTP signature is not present.