Per-Segment Authority Attestation

Mechanism

The per-segment attestation mechanism associates each marker-track segment with a structurally bound attestation record at the moment the segment is admitted to the track. The attestation record is not a separate document referencing the segment by identifier; it is a constituent of the segment, such that any subsequent transmission, storage, or replay of the segment necessarily transmits, stores, or replays the attestation alongside it. The record carries three load-bearing fields: a sensor identity that names the device, authority, or process that produced the segment; an observation timestamp that records the wall-clock instant at which the segment was observed; and a downstream credential that authorizes consumers to act on the segment's contents within a specified scope.

The sensor identity is a stable, externally-resolvable handle. It is not a free-form string; it resolves through a registry to a public-key material with which the attestation is signed and to a manifest describing the sensor's capabilities, calibration history, and known-good operating envelope. Consumers presented with a segment may verify the signature against the resolved key and may consult the manifest to determine whether the observation timestamp falls within a window during which the sensor was operating within its known-good envelope. Segments produced by sensors outside their known-good envelope are not rejected at admission but are flagged in the attestation, allowing downstream consumers to make policy decisions about whether to consume them.

The observation timestamp is monotonic with respect to the producing sensor and bears a precision sufficient to disambiguate consecutive observations from that sensor. It is not the timestamp at which the segment was admitted to the track, nor the timestamp at which any consumer first reads the segment; it is the instant at which the underlying sensing event occurred. The distinction is material: forensic reconstruction frequently turns on the order of physical events, not the order in which their representations propagated through the substrate, and an attestation that conflates the two cannot answer questions of physical sequence.

The downstream credential names the scope under which consumers may act on the segment. The credential is not a permission granted to a specific consumer; it is a description of the class of actions the segment authorizes, such that any consumer holding the corresponding authority may rely on the segment for actions within that class. A segment may carry a credential authorizing it for use in real-time control, in archival forensic review, in regulatory reporting, or in any combination thereof; consumers operating outside the named scopes must obtain corroborating evidence rather than relying on the segment alone.

Operating Parameters

Each per-segment attestation record is parameterized by at least six values. The sensor identity is a handle drawn from the producer registry. The observation timestamp is a monotonic timestamp at the sensor's native precision, conventionally microseconds for physical sensors and milliseconds for inferential producers. The downstream credential is a structured descriptor naming one or more action scopes. A signature value covers the segment payload together with the preceding three fields, computed under the producer's private key and verifiable against the registry-resolved public key. A producer-registry version identifier locates the registry snapshot against which the signature is to be verified, enabling forensic verification even after the registry itself has evolved. A scope-policy version identifier locates the policy under which the credential's named scopes are to be interpreted, providing the same forward compatibility for credentials that the registry version provides for keys.

Attestation records are produced at admission time and are immutable thereafter. The architecture explicitly forbids in-place modification of attestation fields once a segment has been admitted; corrections take the form of new segments superseding prior ones, with the supersession relationship itself recorded in the track structure rather than by overwriting. This discipline ensures that any forensic replay of the track can reconstruct both the originally-attested state and the corrected state, distinguishing genuine sensor evolution from after-the-fact revision.

The signature scheme is chosen to support both verification under the registry version current at admission time and re-verification under future registry versions that may rotate keys. The architecture is agnostic to the specific signature primitive; in deployed configurations it is conventionally an elliptic-curve signature over a hash of the canonicalized record. Canonicalization is essential to prevent serialization-dependent verification failures and is performed against a published canonical form fixed at the time of segment admission.

Per-segment attestation is sized to be carried inline with the segment payload without imposing prohibitive overhead. In typical deployments the attestation contributes a small additive overhead per segment, dominated by the signature value, with the remaining fields contributing a constant of less than one hundred bytes. The overhead is justified by the forensic and operational properties it enables and is not configurable downward to omit fields; deployments requiring extreme density may reduce timestamp precision or signature size but may not omit the structural fields entirely.

Alternative Embodiments

In a first alternative embodiment, the attestation record additionally carries a quality-of-observation scalar describing the producer's self-reported confidence in the segment. The scalar enables consumers to weight or filter segments by producer confidence without consulting the producer manifest, at the cost of a small additional payload and the requirement that the producer self-report honestly within the constraints of its calibration regime.

In a second alternative embodiment, the downstream credential is replaced by a structured capability expression admitting Boolean combinations of scopes. The capability-expression embodiment supports finer-grained authorization decisions, for example authorizing a segment for real-time control only when corroborated by a second segment within a configured time window, at the cost of additional consumer-side logic.

In a third alternative embodiment, the attestation is detached from the segment payload and stored in a parallel attestation track linked by content hash. The detached embodiment reduces the per-segment overhead in storage scenarios where the payload is replicated more aggressively than the attestation, at the cost of additional indirection at consumption time and the operational requirement to keep the two tracks synchronized.

In a fourth alternative embodiment, the attestation incorporates a chained predecessor reference, identifying the immediately preceding segment from the same producer by content hash. The chained embodiment provides per-producer tamper-evidence: alteration or deletion of any segment in the chain breaks the chain at and after that point, and the break is detectable on replay without recourse to external evidence.

In a fifth alternative embodiment, the attestation is co-signed by a second authority distinct from the producing sensor — typically a jurisdictional witness or a regulatory observer. Co-signing addresses scenarios in which the producing sensor's authority alone is insufficient to authorize downstream action, for example when admitting segments produced by third-party sensors into a regulated control loop.

Composition with Other Primitives

Per-segment attestation composes with the marker-track admission primitive: admission verifies the attestation signature against the producer registry, evaluates the observation timestamp against the producer's known-good window, and evaluates the downstream credential against the track's admission policy. Segments failing any of these checks are either rejected outright or admitted with a flagged attestation that records the nature of the failure for downstream consumers to consider.

Per-segment attestation composes with the marker-track replay primitive by enabling replay at the granularity of individual segments under the attestation in force at admission. A forensic investigator may replay a single segment, the chain of segments produced by a single sensor, or the entire track, with verification proceeding at the segment level rather than at the track level. Track-level replay reduces to the conjunction of per-segment replays without requiring a separate track-level attestation.

Per-segment attestation composes with the credentialed-consumer primitive by supplying the downstream credential against which consumer authority is evaluated. Consumers presenting authority for scopes named in the credential may act on the segment; consumers without such authority must obtain corroborating evidence or escalate. The composition is decentralized: the segment carries enough information to govern its own consumption without requiring consumers to consult an external authorization service per read.

Prior-Art Distinction

Cryptographic attestation of telemetry is a long-established practice in security-sensitive domains, including secure-boot measurement chains, signed log streams, and credentialed sensor feeds. The novelty here is not the use of cryptographic attestation but its placement at the segment granularity within a marker-track substrate, with each segment carrying its own structurally bound attestation record rather than inheriting attestation from an enclosing track or container.

Prior signed-log architectures conventionally attest at the file, batch, or session level. Such architectures cannot answer forensic questions about the provenance of an individual record without trusting the enclosing container, and cannot distinguish between a tampered record and a tampered container. The per-segment architecture disclosed here makes the segment the unit of attestation, ensuring that questions of provenance can be answered for any single observation without invalidating the surrounding evidence and without requiring trust in container-level structures.

Prior sensor-fusion architectures often attach metadata to individual observations, including sensor identifiers and timestamps, but treat the metadata as advisory rather than authoritative and do not bind it cryptographically to the observation. The architecture disclosed here makes the metadata authoritative through the signature and resolves it to externally-verifiable identities through the producer registry, enabling forensic determinations that advisory metadata cannot support.

Disclosure Scope

This disclosure covers the structural binding of an attestation record to each segment of a marker-track substrate, with the record carrying at minimum a sensor identity resolvable through an external registry, an observation timestamp at the producer's native precision, and a downstream credential naming the scopes under which the segment may be consumed, together with a signature covering these fields and the segment payload.

The disclosure encompasses the producer-registry resolution mechanism, the canonical form against which signatures are computed, the immutability discipline forbidding in-place modification of admitted segments, the supersession mechanism by which corrections are introduced as new segments, the registry- and policy-version identifiers that enable forensic verification across schema evolution, and the alternative embodiments enumerated above including quality-of-observation scalars, capability-expression credentials, detached attestation tracks, chained predecessor references, and co-signed attestation.

The disclosure is intended to read on any embodiment in which marker-track segments carry their own attestation records sufficient to support forensic reconstruction at segment granularity, regardless of the specific signature primitive, the encoding of the credential, the choice of registry implementation, or the structure of the surrounding marker-track substrate. The disclosure is independent of the specific physical or inferential sensors that produce segments and applies equally to deployments in transportation, industrial control, regulated logistics, and any other context in which segment-level provenance must be cryptographically determinable.