Mechanism

The disclosed identity model replaces persistent public-private keypairs with memory-native identity: identity evolves as a cumulative sequence of Dynamic Agent Hashes (DAH) and Dynamic Device Hashes (DDH) produced by successive identity mutations. Because nothing in this model is a long-lived credential, the model still has to interoperate with counterparties that expect conventional PKI. Compatibility with legacy PKI-based systems is enabled through a fallback identifier mechanism that preserves strict isolation between memory-native identity evolution and legacy authentication paths. A transient, session-scoped identifier allows interoperability without leaking or importing any information that would affect DAH or DDH continuity.

The mechanism is realized by a legacy-bridge adapter, the subject of FIG. 3. The adapter generates a temporary keypair and a session nonce under a domain-separated context, and from these it derives a fallback identifier as a hash of the public key, the nonce, and the context tag. In the disclosed embodiment the construction is FID = H(PK_pub ∥ nonce ∥ ctx_tag), where PK_pub is the public key of the temporary keypair. The fallback identifier is maintained entirely within an isolation boundary that prevents any interaction with trust-slope update rules. A volatile, in-memory mapping links the fallback identifier to session metadata for the duration of the session.

The Isolation Boundary

The fallback identifier is maintained entirely within an isolation boundary that prevents any interaction with the trust-slope update rules. The isolation boundary enforces strict non-contamination rules. Any attempt to inject PKI material into DAH or DDH, to export DAH or DDH internals to satisfy legacy requirements, or to extend a fallback identifier beyond its authorized scope results in closed-fail termination. Policy may additionally restrict legacy bridging to approved domains or require human approval in sensitive environments.

Because the trust slope never incorporates PKI artifacts, the presence, use, and teardown of a fallback identifier cannot alter or pollute slope continuity. The temporary keypair, the session nonce, and the fallback identifier sit on the far side of the boundary from DAH and DDH formation, which derive their freshness from the model's own unpredictability sources rather than from any PKI material.

Outbound Legacy Communication

For outbound communication, the adapter constructs a legacy-compliant message containing the fallback identifier and a PKI signature produced with the ephemeral private key. Legacy recipients validate the signature under their existing PKI policies, exactly as they would for any conventional counterparty. Throughout this exchange, DAH and DDH formation and trust-slope behavior remain unaffected and continue governing routing, caching, and semantic authorization locally.

The legacy peer therefore sees only what it expects: an identifier and a signature it can verify with its own infrastructure. It gains no view into the memory-native identity behind the adapter, and the model gives up none of its own continuity guarantees in order to be understood by the legacy peer.

Inbound Messages and Audit Binding

For inbound messages, the adapter verifies the counterparty's PKI signature and resolves the corresponding fallback identifier via the local mapping table. When policy requires correlation to a current dynamic identity for audit purposes, the adapter may produce a one-way binding token that states the fallback identifier was serviced while a particular DAH value was active. This token is written to a segregated audit log and has no influence on successor computation or slope continuity.

The binding is deliberately one-way. The token attests that the fallback identifier was serviced while a given DAH was active, but it does not let any legacy-sourced material influence successor computation on the trust slope. Audit correlation is thus available where governance demands it, recorded as an observation in a segregated log rather than as an input that feeds back into identity evolution.

Fallback Identifier Lifecycle

The fallback identifier lifecycle is short-lived and bounded. When a session ends or expires, the mapping entry is deleted, the ephemeral private key is destroyed, and the fallback identifier is invalidated. Optional revocation metadata can be emitted to prevent reuse. Because DAH and DDH never incorporate PKI artifacts, teardown cannot alter or pollute the trust slope.

The compatibility mechanism operates independently of the unpredictability source used for DAH and DDH derivation, whether hardware-anchored, local-state, or hybrid. The adapter functions entirely at the boundary layer and never modifies slope formation, continuity validation, lineage chaining, delayed verification workflows, or checkpoint replay logic. The fallback path is an adjunct to the identity model, not a state of it.

Threat-Surface Position

Within the broader threat model, the fallback mechanism is the model's answer to cross-protocol and downgrade attacks. These are mitigated by isolating legacy-system interoperability within a segregated adapter. Fallback identifiers and PKI signatures never influence DAH or DDH evolution, and attempted crossover triggers closed-fail detection. Session-scoped mappings and explicit teardown prevent persistence, leakage, or correlation across epochs.

An attacker who hopes to use the legacy bridge as a foothold, to splice a PKI-derived value into the trust slope, or to keep a fallback identifier alive past its session encounters a closed-fail boundary rather than a gradual degradation. The legacy path is interoperable but quarantined by construction.

Distinction From Conventional PKI Interoperability

Conventional digital identity and authentication systems rely on persistent public-private keypairs and signature-based validation, which expose users and devices to key compromise, metadata correlation, certificate revocation failure, and susceptibility to quantum cryptographic attacks. Public key infrastructure typically requires centralized trust anchors, global registries, and persistent key material. Approaches that bridge a new identity scheme with such PKI commonly translate the new credential into long-lived key material or carry PKI artifacts into the new scheme's state, coupling the two regimes.

The disclosed mechanism does neither. By scoping fallback identifiers to isolated, ephemeral sessions and restricting their use to a segregated adapter path, legacy interoperability is achieved without weakening memory-native authentication, revealing slope evolution, or enabling cross-domain correlation. Isolation is a property of how identity is computed, since the trust slope is formed from local unpredictability and never from PKI artifacts, rather than a policy applied after the fact.

Disclosure Scope

The fallback identifier mechanism described in this article, comprising a legacy-bridge adapter that generates a temporary keypair and session nonce under a domain-separated context, derives a fallback identifier as FID = H(PK_pub ∥ nonce ∥ ctx_tag) maintained within an isolation boundary excluded from DAH and DDH evolution, services outbound and inbound legacy PKI traffic, optionally emits a one-way binding token to a segregated audit log, and tears the session down by deleting the mapping, destroying the ephemeral private key, and invalidating the identifier, is disclosed in U.S. Application No. 19/388,580. This article describes that disclosed mechanism. The scope extends to deployments in which DAH and DDH derive from a hardware anchor, from a local-state vector, or from a hybrid of both, provided that fallback identifiers and PKI signatures never influence slope formation and that any attempted mixing of PKI artifacts with slope formation triggers closed-fail detection.