Mechanism
Entropy anchor rotation is a rotation mechanism that maintains freshness, forward secrecy, and policy alignment by periodically regenerating an entropy anchor and reinitializing the trust slope. In this identity substrate, identity is not a static credential or a persistent keypair. It is a trust slope: the cumulatively validated sequence of Dynamic Agent Hashes (DAHs) or Dynamic Device Hashes (DDHs) formed by successive, verifiable identity mutations. Rotation regenerates the anchor and starts a new slope without breaking verifiability across the transition.
The rotation event is governed by a slope health monitor and a staleness determination rather than a single fixed schedule. When a monitored condition meets policy-defined thresholds, a staleness determination triggers reseeding of the identity process. Upon reseeding, the system generates a new entropy anchor, derives a new initial identity from it, constructs a fresh trust slope, and records a forward link that cryptographically binds the terminal value of the prior epoch to the newly established initial identity. The forward link is what lets downstream verifiers reconcile pre-rotation and post-rotation slopes using only local policy and bounded proofs, without global registries or synchronized ledgers.
Staleness Detection
Rotation begins with the slope health monitor. The monitor evaluates staleness indicators such as elapsed-epoch limits, observed drift or cadence anomalies, entropy reuse heuristics, degradation in trust behavior, or compromise signals emitted by the substrate. These are the indicators disclosed in the specification. They are evaluated against policy-defined thresholds, and when a monitored condition meets those thresholds, the staleness determination triggers the reseed event.
Because the trigger is a policy-evaluated condition, the specification does not fix the threshold values. It fixes the structure: a monitor that watches the named indicators and a determination step that converts a threshold crossing into reseeding of the identity process.
Reseeding and the New Anchor
Upon reseeding, the system generates a new entropy anchor and derives a new initial identity for the device or agent. The anchor draws from the same permitted unpredictability sources used throughout the identity process. In hardware-anchored embodiments, the anchor is derived from a keyed function applied to a static hardware identifier and a fresh volatile salt. In local-state embodiments, it is derived from a stability-tuned local state vector processed by a strong extractor. In hybrid embodiments, both contributions are combined. There is no rotation-specific entropy primitive: rotation reuses the system's existing entropy sources.
The new initial identity is computed using the same update rule applied throughout the identity process, with a versioned domain separator that distinguishes anchor epochs. From this freshly derived initial identity, a new trust slope is then constructed, advancing forward only under the standard update rule.
The Forward Link
To preserve verifiability across the transition, a forward link is recorded that cryptographically binds the terminal value of the prior epoch to the newly established initial identity. This forward link enables downstream verifiers to reconcile pre-rotation and post-rotation slopes using only local policy and bounded proofs, without requiring global registries or synchronized ledgers.
The specification describes the forward link by what it binds, the terminal value of the prior epoch and the new initial identity, rather than by a fixed field layout. A verifier uses the forward link to bridge old and new anchors under policy, which is sufficient to reconcile the two epochs without contacting any external authority.
Epoch Treatment Policies
Rotation policies determine how previous epochs are treated, and the specification contemplates more than one. In some embodiments, the pre-rotation slope is made read-only and excluded from future successor validation, marked for archival, and protected by replay prevention rules that reject reuse of identifiers from the retired epoch.
In other embodiments, a grace window temporarily permits parallel acceptance of both epochs solely for bridging proofs that traverse the forward link. The grace window lets traffic that still references the old epoch be reconciled to the new one. The choice between strict retirement and a grace window is a policy decision rather than a change to the underlying mechanism.
Optional Biometric-Assisted Reseeding
Certain embodiments allow biometric-assisted reseeding as an optional source of fresh, non-exported entropy. A biometric sample such as a fingerprint, voiceprint, or behavioral feature is pre-processed, passed through a privacy-preserving fuzzy extractor, and transformed into a bounded seed. Optional liveness verification may be applied. The seed is never stored or exported in raw form and is used only locally to augment the entropy anchor derivation.
This embodiment composes cleanly with both hardware-anchored and local-state identities: the biometric contribution augments the anchor derivation rather than replacing the hardware or local-state contribution. It is an optional augmentation to the reseed step, not a separate rotation path.
Deterministic Verifier Handling
Verifiers handle rotation deterministically. When encountering a rotated identity, a verifier requests or receives bounded proofs containing the forward link and the new initial identity. It then replays successors along the new slope and confirms that the new epoch opens to the previous one through the recorded forward link. Because anchor and identity generation draw from the same permitted unpredictability sources, hardware anchor plus volatile salt, local-state vector plus extractor, or a hybrid, the verification process remains uniform across epochs.
The same machinery supports privacy. In privacy-sensitive deployments, the dynamic identity presented in transport headers may rotate at a defined cadence independent of payload semantics to reduce long-range linkability. Verifiers resolve these header-level rotations by opening the corresponding forward links or anchors, ensuring auditability without compromising privacy. Entropy anchor rotation thereby maintains a memory-resolved, high-entropy identity throughout a device or agent's operational life: staleness detection triggers a reseed event, execution continues along a fresh slope, and the forward link preserves continuity and auditability while allowing expiration, archival, and replay protection of prior epochs.
Disclosure Scope
Entropy anchor rotation, comprising a slope health monitor that evaluates staleness indicators, a staleness determination that triggers reseeding, generation of a new entropy anchor from hardware-anchor, local-state, or hybrid unpredictability sources, derivation of a new initial identity under the same update rule with a versioned domain separator that distinguishes anchor epochs, a forward link binding the terminal value of the prior epoch to the new initial identity, policy treatment of retired epochs as read-only and archival with replay prevention or under a temporary grace window for bridging proofs, optional biometric-assisted reseeding through a privacy-preserving fuzzy extractor, and deterministic verifier reconciliation across epochs through the forward link, is disclosed in U.S. Application No. 19/388,580 in the section on entropy anchor rotation and adaptive slope reinitialization and the corresponding drawing. This article describes that disclosed mechanism. The scope extends to embodiments in which the unpredictability source, threshold policy, and epoch-treatment policy vary, provided staleness detection triggers a reseed and a forward link preserves verifiable continuity across the anchor epochs.
