ENC/FER1-RECEIPT/1 — Canonical Encoding for FER/1 Receipts

Status: Draft Owner: Architecture Version: 0.1.0 SoT: Yes Last Updated: 2025-12-01 Linked Phase Pack: PH07 Tags: [evidence, receipt, deterministic, execution]

Document ID: ENC/FER1-RECEIPT/1 Profile ID: FER_ENC_RECEIPT_V1 = 0x0301 TypeTag: TYPE_TAG_FER1_RECEIPT_1 = 0x00000301

Depends on (normative):

ASL/1-CORE v0.4.x — value model (Artifact, Reference, OctetString)
ENC/ASL1-CORE v1.0.x — canonical encoding for Reference
FER/1 — receipt semantics and required fields

0. Overview

ENC/FER1-RECEIPT/1 defines the canonical binary encoding for FER/1 receipts. Receipts are stored as ASL/1 Artifacts with:

Artifact.type_tag = TYPE_TAG_FER1_RECEIPT_1
Artifact.bytes    = ReceiptBytes

This encoding is deterministic and injective. Ordering is fixed and list ordering is required for canonicalization.

1. ReceiptBytes Layout (v1)

All integers are big-endian. Lengths are unsigned.

ReceiptBytes =
  fer1_version         : U16
  function_ref         : EncodedRef
  input_manifest_ref   : EncodedRef
  environment_ref      : EncodedRef
  evaluator_id_len     : U32
  evaluator_id_bytes   : BYTES
  output_ref           : EncodedRef
  executor_count       : U32
  executor_refs        : EncodedRef[executor_count]
  parity_count         : U32
  parity_entries       : ParityEntry[parity_count]
  started_at           : U64
  completed_at         : U64

Rules (normative):

fer1_version MUST be 0x0001.
parity_count MUST equal executor_count.
Every ParityEntry.output_ref MUST equal the top-level output_ref.
parity_entries[i].executor_ref MUST equal executor_refs[i].
started_at MUST be less than or equal to completed_at.
executor_refs and parity_entries MUST be ordered by ascending EncodedRef byte order to ensure canonicalization.

2. EncodedRef

EncodedRef embeds an ASL/1 Reference using a length prefix:

EncodedRef =
  ref_len   : U32
  ref_bytes : BYTES   // ReferenceBytes (ENC/ASL1-CORE v1)

ref_len is the length of ReferenceBytes. ReferenceBytes uses the canonical encoding from ENC/ASL1-CORE v1.

3. ParityEntry

ParityEntry =
  executor_ref      : EncodedRef
  output_ref        : EncodedRef
  has_sbom_ref      : U8
  sbom_ref?         : EncodedRef  // if has_sbom_ref == 1
  parity_digest_len : U32
  parity_digest     : BYTES

parity_digest is an opaque, executor-specific digest. Empty digests are allowed (parity_digest_len = 0).

4. Canonicalization and Validation

Implementations MUST:

enforce list ordering for executor_refs and parity_entries,
reject truncated payloads or trailing bytes, and
reject any receipt where required references are malformed or invalid.

No other metadata or policy is embedded in the receipt bytes.

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