Proximity-Grounded Multi-Party Coordination

Mechanism

A coordination class declares the set of participants required to admit an event together with a proximity profile that those participants must jointly satisfy at the moment of coordination. The proximity profile is expressed as one or more constraints over the participants' joint spatial and temporal estimates: a maximum pairwise range, a containing geofence, a sensor-range overlap, a communication-range adjacency, or a jurisdictional containment. Each participant runs in a mesh that produces credentialed coordinate and time observations through ranging exchanges with neighbors; those observations are not unilateral assertions by the participant but joint products of the exchanges, with each contributing endpoint named and credentialed in the resulting record.

When a coordination event is initiated, every nominated participant contributes a current proximity attestation drawn from its mesh observations. The coordinator assembles the attestations, evaluates the declared proximity profile against the joint estimate, and admits the event only if every constraint resolves true under the credentialed lineage of the contributing observations. The admission check is symmetric in form to the cryptographic threshold check that any multi-party coordination scheme must perform: an unsatisfied proximity constraint produces the same kind of structured rejection as a missing or invalid signature, with a declared reason and a referenced observation. The coordination record that emerges from a successful admission carries both the participant signatures and the proximity attestation, and any later audit evaluates them together rather than treating proximity as out-of-band metadata.

The mechanism is distinct from threshold signatures, multi-party computation, and group signatures, all of which establish that some quorum of credentialed key-holders agreed to a message but say nothing about where those key-holders were. It is also distinct from location attestation schemes that bolt a self-reported GPS reading onto a signed payload; here, the proximity claim is constructed from cross-attested ranging exchanges in which neighbors observe each other, so a single compromised endpoint cannot fabricate a position consistent with the joint mesh estimate without colluding with the neighbors that would otherwise contradict it.

The collusion threshold is therefore not a single-endpoint compromise but a coordinated compromise across an observer-diversity-set whose membership is determined by the deploying operator's mesh topology and freshness requirements rather than by the attacking party. In practice, an adversary attempting to forge a coordination admission must compromise enough credentialed neighbors that the joint estimate produced by the mesh's normal solver remains consistent with the forged claim, while leaving no diagnostic trace in the cross-residuals between honest and dishonest observations. The architecture surfaces those residuals as part of the routine evaluator output, so a coordination that admitted under a marginally consistent attestation is detectable in audit even when no constraint was strictly violated at admission time.

Operating Parameters

Proximity profiles are parameterized along four primary axes. The first is the spatial constraint shape and tolerance: a pairwise maximum range admissible to a tolerance of, for instance, one meter for a surgical-team coordination, ten meters for a building-level fire-response coordination, or one kilometer for a tactical formation. The second is the temporal binding window: the latency between the timestamp of the contributing ranging observations and the coordination event itself, which a profile may bound at tens of milliseconds for engagement-grade coordination or several seconds for civil-infrastructure dispatch. The third is the freshness and observer-diversity requirement: how many independent neighbors must have contributed to each participant's current position estimate, and within what recency, to defeat replay of stale attestations. The fourth is the failure semantics: whether a single participant's proximity failure aborts the entire coordination, demotes it to a lower coordination class, or admits it with a recorded caveat.

Operationally, the mesh supplies the inputs at a rate determined by the ranging schedule. UWB-class ranging exchanges may run at tens of hertz per pair, producing a continuously refreshed joint estimate against which a coordination admission can be evaluated without imposing additional ranging traffic on the moment of coordination itself. Lower-rate modalities — acoustic ranging in a surgical theater, optical time-of-flight in a manufacturing cell — set a correspondingly slower admission cadence. The architecture treats the ranging rate, the temporal binding window, and the freshness requirement as a single coupled tuning that the deploying operator declares per coordination class, and it refuses to admit a coordination whose declared profile cannot be satisfied by the mesh's actual observation rate.

A coordination class declaration also fixes the credentialing policy for admissible observations and the audit-record granularity. The policy names the credential roots whose attestations the evaluator will accept, the minimum cardinality of independent observers per participant, and the disposition of observations whose credential has lapsed or been revoked between observation time and admission time. The audit-record granularity declares whether the coordination event archives only the admission verdict, the verdict together with summarized covariances, or the verdict together with the full underlying observation tuples, the last suitable for high-assurance deployments where after-the-fact reconstruction of the admissibility decision is itself a regulatory requirement.

Alternative Embodiments

In a defense embodiment, an engagement-authorization coordination requires that the authorizing officer, the platform commander, and the weapon-system operator be jointly within a declared command post and that their proximity attestations be no older than a specified mission-time window. The coordination record is later auditable against the contemporaneous mesh log, and a coordination that admitted on a stale or single-observer attestation is detectable in audit even if the cryptographic signatures were valid.

In a medical embodiment, a high-risk surgical step requires that surgeon, anesthesiologist, and circulating nurse be jointly within the sterile field defined by the operating-theater geofence during the coordination event. A relaxed sub-class admits remote consultation by a credentialed off-site reviewer whose proximity constraint is replaced by a network-latency and identity-attestation profile, with the relaxation explicitly recorded in the coordination class declaration and surfaced in audit.

In a civil-infrastructure embodiment, a substation switching operation requires the field crew, the dispatch operator, and the safety officer to satisfy a proximity profile that combines a field-side geofence around the apparatus with a control-room geofence around the dispatcher console. In a financial or governance embodiment, proximity-grounded coordination is used for board quorum or vault access where spatial co-location is a chartered requirement that has historically been attested by sign-in sheets and is here attested structurally.

In a degraded-mesh embodiment, the architecture admits a fall-back proximity class that accepts attestations from a reduced set of observers when the mesh is partitioned, with the reduced confidence carried into the coordination record so downstream consumers can apply a corresponding caution to events admitted under the degraded profile.

In an autonomous-systems embodiment, multi-vehicle coordination — a swarm formation change, a multi-robot manipulation handoff, a convoy reconfiguration — is admitted only when the joint mesh estimate places every participant within the geometric envelope the maneuver requires; the proximity profile in this embodiment is not a static distance but a parameterized envelope that follows the maneuver's nominal trajectory, evaluated against the observed joint state at the moment of admission and again at the maneuver's completion to record terminal-state compliance.

Composition

Proximity-grounded coordination composes with the mesh's existing ranging and time-consensus subsystems by drawing its inputs from them rather than recapitulating them. The same ranging exchanges that produce position estimates and the same piggybacked time observations that bound mesh drift feed the proximity evaluator. It composes upward with the credentialed-event architecture by treating proximity attestation as one more admissibility predicate alongside signature validity, role authorization, and policy compliance; the coordination evaluator runs the predicates uniformly and emits a single admission or rejection record. It composes laterally with conventional multi-party signing protocols, which can be operated unchanged at the cryptographic layer while the coordination class wraps them with the proximity admissibility envelope.

Downstream, the architecture composes with policy and audit infrastructure that consumes coordination records. Because proximity is a first-class admissibility element rather than ancillary metadata, audit queries that filter or aggregate coordination events by spatial-temporal attributes — for example, all engagement authorizations admitted within a particular command post during a particular operational window — are answered against the same record store that holds the cryptographic signatures, with the same credentialed lineage and the same revocation semantics applied uniformly across both classes of admissibility predicate.

Prior Art Distinction

Threshold and multi-party signature schemes (BLS aggregation, FROST, GG18 and successors) establish cryptographic agreement among key-holders but make no claim about where those key-holders were when they signed. Distance-bounding protocols (Brands-Chaum and descendants) establish a bound on the distance between two endpoints during a single exchange but do not lift that bound into a multi-party admissibility predicate evaluated against a coordination class. Location-based access control systems append self-reported or single-source location attestations to authentication tokens, with no joint cross-attestation among the access-requesting parties. The disclosed architecture differs in that proximity is a coordination-class-declared, multi-party, cross-attested admissibility predicate evaluated at the same structural layer as cryptographic claims, with the proximity record carried into audit as a first-class element of the coordination event.

Disclosure Scope

The disclosure covers coordination architectures in which a declared proximity profile over multiple participants is evaluated against credentialed mesh-derived joint position and time observations as a precondition for admitting a coordination event, in which the proximity attestation is recorded into the coordination record and evaluable in audit, and in which the proximity admissibility is composed with cryptographic and policy admissibility under a uniform evaluator. The disclosure includes embodiments across defense, medical, civil-infrastructure, governance, and access-control domains, and across ranging modalities including UWB radio, acoustic, optical time-of-flight, and hybrid combinations. It includes the degraded-mesh fall-back behavior, the per-class declaration of profile, freshness, and failure semantics, and the structural composition with existing multi-party signing protocols.