Attestation Reconciliation Protocol

This document specifies the Attestation Reconciliation Protocol (ARP), a deterministic, bilateral, zero-knowledge-capable mechanism for reconciling verification claims against a plurality of sovereign authoritative registers without raw register records leaving their data-residency jurisdiction. ARP extends the SCITT (Supply Chain Integrity, Transparency, and Trust) architecture to cross-sovereign claim reconciliation. A reconciliation server canonicalises a structured claim, projects it through register-specific controlled projection functions producing the greatest-lower-bound predicate supported by each addressed register, transmits register-specific ciphertexts, receives partial attestations whose payload discloses only a verdict and an optional divergence axis, aggregates the partial attestations through either homomorphic or hash-linkage aggregation, and seals the resulting reconciliation output against a policy-version hash. An append-only cross-jurisdictional settlement- layer ledger records only hashes, with no content. The protocol supports retroactive re-evaluation of historical reconciliations under updated pattern libraries or policy versions without bilateral renegotiation, and a cryptographic-primitive-upgrade path including post-quantum primitives.