Signed Memory Projection Records for Verifiable AI Context Delivery

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Table of Contents

1. Introduction

A memory-object format and a context-delivery record answer different questions. A memory-object format can prove that an object verified under a key accepted at read time. It does not, by itself, identify the set, order, framing, or exact bytes selected for a particular AI request. Conversely, a projection record cannot repair invalid source provenance. It can only preserve the source decision and bind it to the bytes emitted by a named adapter.¶

This document defines the join between those layers. A projection producer signs one closed record after the projection bytes and their ordered fragments are finalized. A verifier recomputes the source-object, fragment, and complete-projection commitments and verifies the adapter signature under a relying-party-pinned key. The resulting fact is narrow: the producer attests that it emitted the committed projection under the committed selection context.¶

The source memory profile remains authoritative for its own object, cryptographic, trust, authorship, and custody semantics. In particular, ApertoMemory [I-D.ferro-apertomemory] remains authoritative for sealed Memory Objects and its read-time trust derivation. This document does not redefine those semantics. It defines a joint, provider-neutral artifact above that boundary.¶

2. Scope and Nonclaims

A conforming Memory Projection Record establishes all of the following:¶

• the adapter identity and pinned signing key used to produce the record;¶
• commitments to the recall request, selection policy, source-profile trust snapshot, and framing profile;¶
• the ordered list of source objects selected, with the trust and authorship results supplied by the source profile;¶
• the exact bytes of each framed context fragment and of the complete emitted projection; and¶
• the number of objects excluded for each closed exclusion reason.¶

A projection record does not establish transport receipt, insertion into a model context window, model use or weighting, action linkage, action authorization, execution, or outcome. A downstream system MAY bind the projection digest into a separate request, authorization, or outcome protocol. Such a binding is outside this document.¶

3. Terminology

Source profile

The independently governed memory format and verification rules from which object identity, trust, authorship, and custody facts are derived.¶

Projection producer

The adapter that selects source objects, frames exact context fragments, constructs the complete projection, and signs the Memory Projection Record.¶

Projection

The exact byte string emitted by the producer for downstream context delivery.¶

Context fragment

The exact framed bytes contributed by one selected source object at one position in the projection.¶

Trust snapshot

A commitment to the source-profile trust state used when the selection decision was made. For ApertoMemory this is a read-time keyring snapshot, because trust is derived rather than stored in the object.¶

b64u

Unpadded base64url encoding as defined in Section 5 of [RFC4648].¶

4. Memory Projection Record

MEMORY-PROJECTION-RECORD-v1 is a closed I-JSON object [RFC7493]. The top-level members are shown below. Member order in a JSON serialization has no significance. Unknown members MUST be refused until a later version defines an extension mechanism.¶

{
  "@version": "MEMORY-PROJECTION-RECORD-v1",
  "source_profile": "draft-ferro-apertomemory-02",
  "projection_id": "urn:memory-projection:example:1234",
  "created_at": "2026-07-29T17:00:01.000Z",
  "adapter": {
    "id": "urn:memory-adapter:example:1",
    "key_id": "adapter-key-2026-07"
  },
  "selection_context": {
    "recall_request_digest": "sha256:...",
    "selection_policy_digest": "sha256:...",
    "trust_snapshot_digest": "sha256:...",
    "trust_evaluated_at": "2026-07-29T17:00:00.000Z",
    "context_frame_profile": "urn:apertomemory:context-frame:v0"
  },
  "delivered": [
    {
      "position": 0,
      "object": {
        "format_version": 2,
        "sealed_object_digest": "sha256:..."
      },
      "context_fragment_digest": "sha256:...",
      "derived_trust": "trusted",
      "authorship": "attested",
      "author_key_id_b64u": "0FMJy9O1Xzs",
      "custody_present": true
    }
  ],
  "exclusions": {
    "total": 2,
    "by_reason": {
      "authentication_failed": 1,
      "schema_invalid": 0,
      "policy_filtered": 0,
      "context_limit": 1
    }
  },
  "projection": {
    "encoding": "utf-8",
    "byte_length": 314,
    "digest": "sha256:..."
  },
  "nonclaims": {
    "model_use": "NOT_ESTABLISHED",
    "action_linkage": "NOT_ESTABLISHED",
    "action_authorization": "NOT_ESTABLISHED",
    "execution_outcome": "NOT_ESTABLISHED"
  },
  "proof": {
    "alg": "Ed25519",
    "key_id": "adapter-key-2026-07",
    "signature_b64u": "..."
  }
}

5. ApertoMemory Source Profile

This section defines the source-profile processing used when source_profile equals draft-ferro-apertomemory-02 and context_frame_profile equals urn:apertomemory:context-frame:v0. The source-native outputs remain governed by [I-D.ferro-apertomemory]. The projection producer MUST preserve those outputs and MUST NOT upgrade or reinterpret them.¶

The embedded requirements below reproduce the ratified [AMEM-TRUST-SNAPSHOT-PROFILE] and [AMEM-CONTEXT-FRAME-PROFILE] profiles pinned at ApertoMemory commit 48be525.¶

single accepted key:
  a2014863c1e89c009c5ad7028148d05309cbd3b55f3b
  sha256:ad677e36d1ac311f758cefeb41069704d1bc995612db0bc1029e239ecfcc2b5d

two accepted keys, raw-byte order:
  a201480102030405060708028248000000000000000148d000000000000000
  sha256:a6cec9a790d68dda6df60477c802cd3738650cd8f1b38fcc21125de51762e231

empty accepted-key set:
  a2014863c1e89c009c5ad70280
  sha256:eddde59fb79cca10fdadf0c5bfc7c3b7e466cab79dcb95a5c4ea165fc8eb5bf0

"[ApertoMemory trust=" + trust
+ " authorship=" + authorship
+ " author_key=" + author_key
+ " custody=" + custody
+ "]\n"
+ body
+ "\n[/ApertoMemory]\n"

6. Canonicalization and Signature

Every member except proof is inside the signature boundary. The producer removes proof, canonicalizes the remaining object with JCS [RFC8785], prefixes the following UTF-8 domain string and one zero octet, and signs the resulting bytes with Ed25519 [RFC8032]:¶

MEMORY-PROJECTION-RECORD-v1\0 || JCS(record without proof)

proof.alg MUST equal Ed25519. signature_b64u is the unpadded base64url encoding [RFC4648] of the 64-byte signature. The public key MUST come from relying-party policy or an authenticated key-distribution mechanism outside the record. A key carried with the record is not a trust anchor.¶

7. Producer Algorithm

1. Open and verify candidate objects using their native source profile. Record the trust snapshot and evaluation time.¶
2. Commit to the recall request and complete selection policy before selecting objects.¶
3. Apply authentication, schema, policy, ordering, and size rules. Count every excluded candidate under exactly one exclusion reason.¶
4. Construct each final context fragment, hash its exact bytes, and append its entry in order. After this step the fragments MUST NOT be mutated without rebuilding the record.¶
5. Concatenate the fragments, compute projection.byte_length and projection.digest, construct the nonclaims, and sign the closed record.¶
6. Return or make available the projection bytes and record as one logical result. A failure after signing but before downstream delivery MUST NOT be reported as proof that a model received the bytes.¶

8. Verifier Algorithm

1. Require the exact top-level and nested member sets defined by this version. Validate types, enumerations, timestamps, and digest syntax.¶
2. Resolve adapter.key_id under relying-party policy, verify that it is current for created_at, and verify the Ed25519 signature over the domain-separated JCS bytes.¶
3. Enforce freshness policy for created_at and trust_evaluated_at and reject a duplicate projection_id when policy requires single use.¶
4. If relying on the request, policy, or trust snapshot, recompute its digest under the named profile.¶
5. Verify each exact source-object digest under its native source profile. Preserve, rather than reinterpret, the native trust, authorship, and custody result.¶
6. Require sequential positions. Recompute every fragment digest from the exact fragment bytes, concatenate those bytes in order, and verify the complete length and digest.¶
7. Verify that exclusions.total equals the sum of the closed reason counters and that all four nonclaims equal NOT_ESTABLISHED.¶

A verifier MUST refuse mutation, omission, duplication, or reordering of a delivered entry; a fragment or projection mismatch; an unpinned, expired, or compromised adapter key; a stale trust evaluation; a count mismatch; an unknown field; an altered nonclaim; or an invalid signature.¶

9. Composition with Downstream Systems

A downstream protocol may bind projection.digest and projection_id into a model invocation, action proposal, authorization, admission decision, execution receipt, or outcome record. That downstream protocol is authoritative for its own semantics. The Memory Projection Record MUST remain valid and useful without requiring any particular agent, authorization, or outcome framework.¶

EMILIA Trusted Context, AEC, Gate, and Outcome Binding are one consumer profile. They may use the projection as one evidence leg and independently bind the actual action and consequence. They are not part of the neutral projection-record wire format and do not authorize changes to the source profile or projection record.¶

10. Security Considerations

A signed projection can preserve poisoned content with high integrity. Producers MUST therefore apply the native source profile fail closed and MUST keep unverified content distinguishable from self or trusted content. The projection signature proves an adapter statement, not the correctness of a memory, trust policy, keyring, framing policy, or model behavior.¶

Stable object identifiers and excluded-object lists create correlation and membership oracles. This version commits to exact source bytes and carries aggregate exclusion counts rather than cleartext source identifiers. Deployments SHOULD use pairwise adapter identifiers where appropriate and SHOULD minimize retention of request, policy, and projection material.¶

Replay can cause an old but valid projection to be applied under a new request. Relying parties MUST enforce freshness and SHOULD register projection_id atomically when single use is required. A stale or revoked source keyring, adapter key, or policy MUST NOT be made current merely by replaying a valid historical signature.¶

11. Privacy Considerations

Memory projections can contain highly sensitive personal facts and can reveal selection behavior even when source objects remain encrypted. Records SHOULD carry commitments rather than cleartext requests, policies, trust snapshots, or excluded identifiers. The projection bytes SHOULD be disclosed only to the intended downstream recipient. Logs SHOULD avoid storing raw projection or fragment bytes unless operationally required.¶

12. IANA Considerations

This document has no IANA actions.¶

13. Implementation Status

The Apache-2.0 implementation [AMEM-EMILIA-INTEROP] implements MEMORY-PROJECTION-RECORD-v1. It produces and verifies the closed neutral field set and v1 domain-separated Ed25519 signature, recomputes the exact recall-request, policy, trust-snapshot, source-object, fragment, and complete-projection commitments, preserves source-native trust results, and exercises positive and hostile mutation vectors.¶

ApertoMemory and EMILIA first independently reproduced five native source-fact cases and matched their exact source-object digests and native trust, authorship, signer, author, and custody results. Separate producers then converged byte-for-byte on a frozen Projection v1 example. That exercise exposed the two underspecifications resolved in Section 5. ApertoMemory subsequently published the exact context-frame and trust-snapshot profiles at pinned commit 48be525, and EMILIA independently reproduced the three deterministic CBOR examples and both checked context-frame digests before adopting those bytes.¶

This is bounded reciprocal evidence for the checked source facts, profile bytes, and Projection v1 cases. It is not blanket ApertoMemory conformance, does not establish that every hostile case has a second independent implementation, and establishes none of model receipt, model use, action linkage, action authorization, execution, or outcome.¶

14. Changes Since -00

This revision makes no change to the MEMORY-PROJECTION-RECORD-v1 wire field set or signature domain. It specifies the exact ApertoMemory deterministic-CBOR trust snapshot and context-frame bytes, updates the example to name that framing profile, and records the bounded reciprocal implementation evidence completed after -00.¶

15. Acknowledgments

The authors thank Matteo Clementel for his review and contributions to the memory-projection boundary.¶

Authors' Addresses