Dynamic Agent Hash Derivation: Deterministic Identity From Memory and Mutation History

Mechanism

DAH derivation is implemented as a pure function of three inputs and produces a fixed-width identity fingerprint that the execution platform consumes wherever authority must be asserted: at capability invocation boundaries, at inter-agent message dispatch, at memory commit, and at lineage append. The function is deterministic and side-effect-free, so any party in possession of the inputs can recompute the DAH and any party in possession of the DAH and two of the inputs can verify the third.

The first input is the device-thread descriptor, a structured value uniquely identifying the host and the execution thread on which an agent cycle is running. The descriptor is itself a hash over fields including the host's attestation root, the execution thread's instantiation identifier, the kernel and runtime version against which the thread was launched, and the trust zone identifier of the substrate. The descriptor is stable across cycles within a thread and changes only when the thread is recreated, the substrate is re-attested, or the trust zone is reconfigured.

The second input is the capability tier, a discrete value drawn from a small ordered set that classifies the authority required for the operation about to be performed. Tiers are not roles in an ACL sense; they are structural classes that determine which downstream substrate paths the resulting DAH is admissible at. A DAH derived under one tier is uncomputable as a DAH at a higher tier, because the tier value is mixed into the derivation and the higher-tier verifier rejects any fingerprint produced under a lower-tier mix.

The third input is the epoch nonce, a value that advances on a defined schedule — either wall-clock-bounded, cycle-count-bounded, or event-bounded — and that is published into the platform's epoch ledger at each rotation. The nonce is unpredictable in advance and verifiable after publication; combined with the device-thread descriptor and the tier, it ensures that a DAH valid in one epoch is not valid in the next, regardless of whether the device, the thread, or the tier has changed.

The derivation function is a domain-separated keyed hash: the three inputs are concatenated in canonical order under a domain separator that identifies the platform version and the derivation purpose, and the result is fed through the platform's hash primitive. Domain separation ensures that DAHs derived for distinct purposes — capability invocation, message dispatch, memory commit — do not collide and cannot be substituted for one another. Rotation is explicit: every epoch advance produces a new nonce, every new nonce produces a new DAH for every active thread and tier, and every DAH transition is recorded in the platform's lineage as an observable event with the prior and successor fingerprints both present.

Operating Parameters

The mechanism is parameterized along four axes that operators tune to deployment needs without altering the structural binding of authority to time, capability, and host. Epoch length sets the temporal granularity of authority: shorter epochs reduce the window during which a leaked DAH is exploitable but increase the rate of rotation events that must be propagated and verified. Practical deployments range from sub-second epochs in high-assurance substrates to multi-minute epochs in cost-sensitive deployments, with the choice driven by the threat model rather than by performance.

Capability tier cardinality determines the granularity of authority classes. The reference implementation uses a small ordered set — typically four to eight tiers — chosen so that every operation in the platform maps unambiguously to a single tier and so that tier ordering corresponds to a meaningful escalation in scope. Operators may extend the tier set, but extensions must be ordered consistently with the existing tiers and must be reflected in the domain separator to avoid collisions with prior derivations.

Device-thread descriptor freshness governs how often the descriptor is re-computed from its underlying attestation. In substrates with stable attestation, the descriptor is computed at thread instantiation and reused for the lifetime of the thread; in substrates with re-attestation requirements, the descriptor is recomputed at the re-attestation cadence and the change is treated as a thread-level rotation distinct from the epoch-level rotation.

Nonce publication policy determines how the epoch nonce reaches verifiers. The reference implementation publishes nonces into a tamper-evident ledger that all substrate participants observe; alternative implementations distribute nonces via signed broadcast, via a beacon, or via a verifiable random function whose seed is itself committed in the ledger. In all cases, the nonce is unpredictable to any party prior to publication and verifiable to any party after publication.

Alternative Embodiments

The mechanism admits several embodiments that preserve the structural binding while accommodating substrate variation. In a hardware-rooted embodiment, the device-thread descriptor is computed within a trusted execution environment that signs the descriptor under a hardware key, and the DAH derivation occurs inside the enclave so that the inputs are never exposed in clear to the host operating system. In a software-rooted embodiment, the descriptor is computed against a signed runtime measurement and the derivation occurs in user space, sacrificing some attestation strength for substrate portability.

In a beacon embodiment, the epoch nonce is supplied by an external randomness beacon that all participants observe; this simplifies nonce distribution at the cost of introducing a dependency on the beacon's availability and integrity. In a verifiable-random-function embodiment, each participant derives the nonce locally from a committed seed and an epoch counter, eliminating the broadcast dependency at the cost of requiring all participants to agree on the seed.

In a hierarchical-tier embodiment, the capability tier is itself a structured value carrying sub-tier discriminators, and the derivation function mixes the structured tier in canonical form. This permits fine-grained capability classification without inflating the top-level tier set, at the cost of requiring verifiers to reproduce the canonical form. In a composite-thread embodiment, the device-thread descriptor encompasses multiple cooperating threads on the same host, so that a DAH attests to authority over a thread group rather than a single thread; this supports parallel execution patterns in which authority must be coherent across cooperating workers.

In a delegated embodiment, an agent operating under one DAH may issue a derivation token that authorizes another agent to compute a DAH at a strictly lower tier within the same epoch and device-thread; the delegation is recorded in lineage, is bounded by the issuer's epoch, and cannot be used to escalate tier or extend lifetime.

Composition With Adjacent Mechanisms

DAH derivation composes with the cognition-native execution platform along several seams. At the capability invocation boundary, the capability dispatcher requires a DAH whose tier matches or exceeds the capability's declared minimum tier and whose epoch is current; absent such a DAH, the dispatch is structurally impossible because the dispatcher's verification predicate fails closed. At the message dispatch boundary, an outbound message is signed under the sender's DAH, and the receiver verifies the signature against the sender's published device-thread descriptor and the current epoch nonce; expired or out-of-tier messages are rejected at the receiver without consulting any external authority.

At the memory commit boundary, every commit appends an entry to the agent's append-only lineage that includes the DAH under which the commit was authorized; this binds memory state to authority state and makes it possible to audit, after the fact, which epochs and tiers contributed to which memory transitions. At the lineage append boundary, the lineage hash chain incorporates the DAH so that a lineage segment cannot be re-attributed to a different epoch or tier without breaking the chain.

Composition with the trust slope mechanism is direct: trust slope is computed over a window of DAH transitions, and the structural binding of DAH to device, tier, and epoch ensures that trust slope is a function of authority continuity rather than of opaque reputation. Composition with the substrate migration mechanism is via thread re-instantiation: a migrated thread acquires a new device-thread descriptor at its new substrate, the descriptor change is recorded in lineage, and DAH derivations after migration are structurally distinct from derivations before migration.

Prior-Art Distinction

Conventional approaches to execution-substrate authority fall into three families, each of which the mechanism distinguishes itself from along structural rather than incremental lines. The first family is bearer tokens issued by an authorization service: a token attests to authority for a stated lifetime and is presented at each operation. Bearer tokens are exfiltratable, have lifetimes measured in minutes to hours, and require the authorization service to be reachable at issuance and frequently at verification. The DAH mechanism produces a fingerprint that is not exfiltratable as a credential because possessing the fingerprint does not permit re-derivation without the underlying inputs, and verification requires no service round-trip.

The second family is mutual-TLS identities bound to host certificates: an executing process presents a certificate that asserts host identity, and authority is granted by reference to that identity in an external policy. mTLS identities do not encode capability tier, do not rotate on an execution-cycle cadence, and do not bind to the specific thread or epoch in which an operation occurs. The DAH mechanism encodes all three structurally and rotates explicitly at epoch boundaries.

The third family is capability tokens issued per-operation and verified against a shared secret. These systems achieve fine-grained authority but typically depend on a central issuer and do not bind authority to host attestation or to a verifiable epoch schedule. The DAH mechanism closes those gaps by deriving authority locally from attested inputs and a publicly verifiable nonce, and by recording every derivation transition in a lineage observable to all substrate participants.

Disclosure Scope

The disclosure encompasses the derivation of an authority fingerprint as a deterministic, domain-separated keyed hash over a device-thread descriptor, a capability tier value, and an epoch nonce; the explicit rotation of that fingerprint at epoch boundaries; the recording of rotations as observable events in the platform's lineage; and the structural composition of the fingerprint with capability dispatch, message dispatch, memory commit, and lineage append boundaries within the cognition-native execution platform.

The disclosure encompasses the hardware-rooted, software-rooted, beacon, verifiable-random-function, hierarchical-tier, composite-thread, and delegated embodiments described above, as well as additional embodiments differing in hash primitive selection, descriptor schema, tier cardinality, or nonce publication mechanism without departing from the structural construction. It is not limited to specific cryptographic primitives, attestation roots, or epoch schedules, and it is not limited to any particular substrate technology, hypervisor, or runtime.