Introduction

ACTIS
Autonomous Coordination & Transaction Integrity Standard

ACTIS is a vendor-neutral standard for verifying the integrity of transaction evidence and enabling deterministic replay of its hash chain. It defines formats and verification algorithms so that any party can independently confirm that evidence has not been altered and that recomputed hashes match the recorded transcript.

ACTIS does not adjudicate disputes, assign liability, or execute transactions. It only standardizes how evidence integrity is verified.

Core verification question

Is this transaction evidence cryptographically intact and deterministically reproducible?

Adjudication, settlement, fault assignment, reputation, and risk scoring are out of scope. ACTIS is an integrity layer only.

What ACTIS proves

  • Integrity — Signatures, hash chain, and checksums validate for the transcript (and bundle, when applicable).
  • Replay — Recomputed round hashes and the transcript final_hash match the values recorded in the transcript.
  • Conformance — A conformant verifier produces a canonical verification report with actis_status set to ACTIS_COMPATIBLE, ACTIS_PARTIAL, or ACTIS_NONCOMPLIANT.

What ACTIS does not do

  • Fault or blame determination
  • Reputation, confidence, or risk scoring
  • Settlement, payment, or money movement
  • Claim qualification or underwriting
  • Identity verification beyond what is required to verify signatures

ACTIS does not define application behavior or business logic.

Threat model

ACTIS assumes that transaction evidence may be shared between mutually untrusted parties. Implementations therefore verify integrity under the following threat model:

  • Evidence bundles may be modified after generation.
  • Individual transcript rounds may be removed, reordered, or replaced.
  • Hash values or signatures may be altered.
  • Bundled files may be substituted or tampered with.

ACTIS verification detects these conditions through schema validation, hash-chain recomputation, signature verification, and checksum validation.

ACTIS does not protect against:

  • malicious generation of evidence by a dishonest party
  • incorrect application or business logic
  • identity impersonation outside of signature verification
  • fraudulent off-chain behavior

ACTIS verifies integrity of recorded evidence; it does not guarantee that the evidence itself is truthful.

Implement in four steps

  1. Read the schema and algorithms — Transcript schema defines structure; ACTIS_COMPATIBILITY.md defines normative algorithms (hashing, canonicalization, signing input, checksums, replay).
  2. Generate a transcript — Produce JSON with the required version, fields, valid hash chain, and Ed25519 signatures. Package as a bundle with input/transcript.json, manifest.json, and checksums.sha256.
  3. Run a verifier — A conformant verifier checks schema, hash chain, signatures, and checksums and outputs a verification report.
  4. Run the conformance corpus — Pass tv-001 through tv-008 with expected outcomes to claim ACTIS v1 Verifier Conformance.

Core concepts

  • Transcript — Hash-linked, signed JSON record of a session. Required: version, intent identifier, creation time, rounds (envelope hashes and signatures).
  • Manifest — JSON listing bundle contents. ACTIS-aligned bundles set standard.name to "ACTIS" and list core_files.
  • Bundle — Container (e.g. ZIP) with manifest, transcript at input/transcript.json, and integrity data over core files.
  • Verification report — Canonical JSON with actis_status, schema_ok, hash_chain_ok, signatures_ok, replay_ok, checksums_ok, and warnings.

Next steps

  • Spec — Core structures, verification model, normative references.
  • Resources — Compatibility, schemas, governance, IP.
  • Examples — Test vectors, sample artifacts, conformance usage.
  • GitHub — Canonical specification and test vectors.

Contributing

ACTIS is an open standard and welcomes feedback from implementers, auditors, and infrastructure developers.

Questions, implementation experience, or proposals for improvement can be shared with the maintainers.

Contact: info@actis.world
Specification repository: https://github.com/actis-spec/actis