{"id":50776482,"url":"https://github.com/cardanowall/cip309","last_synced_at":"2026-06-12T00:02:11.173Z","repository":{"id":362058768,"uuid":"1256468692","full_name":"cardanowall/cip309","owner":"cardanowall","description":"An open standard for content timestamping — Proof of Existence anchored on Cardano. Spec, CDDL, JSON Schemas, registries, and conformance vectors.","archived":false,"fork":false,"pushed_at":"2026-06-02T11:20:58.000Z","size":527,"stargazers_count":0,"open_issues_count":0,"forks_count":0,"subscribers_count":0,"default_branch":"main","last_synced_at":"2026-06-02T12:31:15.992Z","etag":null,"topics":["blockchain","cardano","cddl","cip-309","conformance","notarization","proof-of-existence","specification","standard","timestamping"],"latest_commit_sha":null,"homepage":"https://cip309.org","language":null,"has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"apache-2.0","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/cardanowall.png","metadata":{"files":{"readme":"README.md","changelog":"CHANGELOG.md","contributing":"CONTRIBUTING.md","funding":null,"license":"LICENSE","code_of_conduct":"CODE_OF_CONDUCT.md","threat_model":null,"audit":null,"citation":"CITATION.cff","codeowners":null,"security":"SECURITY.md","support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null,"zenodo":null,"notice":null,"maintainers":null,"copyright":null,"agents":null,"dco":null,"cla":null}},"created_at":"2026-06-01T20:06:01.000Z","updated_at":"2026-06-02T11:38:02.000Z","dependencies_parsed_at":null,"dependency_job_id":null,"html_url":"https://github.com/cardanowall/cip309","commit_stats":null,"previous_names":["cardanowall/cip309"],"tags_count":null,"template":false,"template_full_name":null,"purl":"pkg:github/cardanowall/cip309","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/cardanowall%2Fcip309","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/cardanowall%2Fcip309/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/cardanowall%2Fcip309/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/cardanowall%2Fcip309/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/cardanowall","download_url":"https://codeload.github.com/cardanowall/cip309/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/cardanowall%2Fcip309/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":34222709,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-05-26T15:22:16.424Z","status":"online","status_checked_at":"2026-06-11T02:00:06.485Z","response_time":57,"last_error":null,"robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":true,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["blockchain","cardano","cddl","cip-309","conformance","notarization","proof-of-existence","specification","standard","timestamping"],"created_at":"2026-06-12T00:02:10.990Z","updated_at":"2026-06-12T00:02:11.134Z","avatar_url":"https://github.com/cardanowall.png","language":null,"funding_links":[],"categories":[],"sub_categories":[],"readme":"# Label 309 — Proof of Existence on Cardano\n\nLabel 309 is an open standard for **Proof of Existence (PoE)** anchored on the\nCardano blockchain. A publisher hashes content and records the digest — together\nwith optional metadata — on-chain under transaction **metadata label 309**.\nAnyone holding the resulting transaction reference can later prove that _this\ncontent existed on or before the block time_ — without trusting the publisher,\ntheir domain, or any server.\n\nThis repository is the reference home of the standard: the normative\nspecification, the canonical grammar and schemas, the extensible identifier\nregistries, and the cross-implementation conformance vectors.\n\n## Status\n\n**Working draft — pre-1.0.** Label 309 has **not** yet been submitted to the\nformal Cardano CIP process. This repository serves as the reference home for the\nstandard while it is finalized for submission. The wire format and registries\nare stabilizing; expect refinement before a 1.0 release. See\n[CHANGELOG.md](CHANGELOG.md) for what has changed.\n\n## What Label 309 is\n\nA PoE record is a small, canonically encoded structure carried in a Cardano\ntransaction's metadata under label 309. Its primary claim is a **content hash**:\nthe digest of some piece of content the publisher wishes to timestamp. Because\nthe record lives in a settled blockchain transaction, its existence is bounded\nabove by the block time — a fact any observer can confirm independently. A\nverifier needs only the transaction metadata, optionally the original content\nbytes, and a public blockchain explorer; no issuer server is ever required.\n\n## The five invariants\n\n1. **Content-first** — the content hash is the primary claim; everything else is metadata about it.\n2. **Issuer-agnostic** — any wallet can publish; verifiers never trust the publisher.\n3. **Storage-agnostic** — content URIs are an optional plural list (`ar://`, `ipfs://`); hash-only records are valid.\n4. **Standalone-verifiable** — a verifier needs only the transaction metadata, optionally the content bytes, and a public blockchain explorer. No issuer server is required at any step.\n5. **Algorithm-agile** — hashes, AEADs, KEMs, KDFs, and signatures all reference named identifiers from extensible registries; post-quantum migration is additive.\n\n## Verifying a proof\n\nStandalone verifiability is the core promise: anyone can confirm a Label 309 proof\nfrom public inputs alone. The standard defines three verifier roles, each a\nsuperset of the previous:\n\n- **Structural validator** — a pure function over the record's CBOR bytes. No I/O, no signature checks, no decryption. It answers a single question: is this a well-formed Label 309 record?\n- **Public verifier** — fetches the transaction metadata, runs structural validation, and verifies any record-level signatures. It does not decrypt.\n- **Recipient verifier** — a public verifier that additionally holds an X25519 private key, decrypts a sealed PoE, and recomputes the plaintext hashes.\n\n## Repository layout\n\n| Directory      | Purpose                                                                                                     |\n| -------------- | ----------------------------------------------------------------------------------------------------------- |\n| `spec/`        | The normative standard prose — the authoritative definition of Label 309.                                   |\n| `cddl/`        | The canonical CDDL grammar for the on-chain record (`label-309.cddl`).                                      |\n| `schemas/`     | JSON Schemas for the record and its sub-structures.                                                         |\n| `registries/`  | The extensible named-identifier registries: error codes and hash / KDF / signature / KEM / AEAD algorithms. |\n| `conformance/` | Canonical cross-implementation test vectors — the byte-parity source of truth.                              |\n| `examples/`    | Runnable reference implementations (`examples/typescript/`, `examples/python/`).                            |\n\nWire-format specifics — exact byte layouts, CBOR tags, field encodings — live in\n`spec/`, `cddl/`, and `schemas/`, not in this README.\n\n## Reference implementations\n\nReference tooling lives in sibling repositories within the same GitHub\norganization. All three language SDKs are validated against the **same** canonical\nconformance vectors in this repository, and produce **byte-identical** output for\nthe same inputs. That cross-implementation byte-parity is a core guarantee of the\nstandard.\n\n| Repository                                                      | Distribution                                                                                                                               | Summary                                                               |\n| --------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ | --------------------------------------------------------------------- |\n| [`label-309-ts`](https://github.com/cardanowall/label-309-ts)   | npm: `@cardanowall/crypto-core` (primitives), `@cardanowall/poe-standard` (wire format), `@cardanowall/sdk-ts` (SDK + standalone verifier) | The TypeScript reference implementation for browser and Node.         |\n| [`label-309-py`](https://github.com/cardanowall/label-309-py)   | PyPI: `cardanowall-sdk` (import name `cardanowall`)                                                                                        | The Python SDK — a byte-identical parity twin of the TypeScript SDK.  |\n| [`label-309-rs`](https://github.com/cardanowall/label-309-rs)   | crates.io: `cardanowall`                                                                                                                   | The Rust SDK — the byte-parity twin in Rust.                          |\n| [`label-309-cli`](https://github.com/cardanowall/label-309-cli) | crates.io: `cardanowall-cli` (binary `cardanowall`)                                                                                        | A command-line standalone verifier and toolkit built on the Rust SDK. |\n\n## License\n\nThis repository uses a split license:\n\n- **Code, examples, data schemas, CDDL grammar, and conformance vectors** are licensed under **Apache-2.0** — see [LICENSE](LICENSE).\n- **Specification prose** is licensed under **CC-BY-4.0** — see [LICENSE-docs](LICENSE-docs).\n\nInbound contributions are accepted under the **Developer Certificate of Origin\n(DCO)** via a `Signed-off-by` line. There is **no CLA**.\n\n## Contributing\n\nSee [CONTRIBUTING.md](CONTRIBUTING.md) for how to propose changes and the DCO\nsign-off requirement. To report a security issue, see [SECURITY.md](SECURITY.md).\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fcardanowall%2Fcip309","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fcardanowall%2Fcip309","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fcardanowall%2Fcip309/lists"}