--- title: "From sensor to record | Nexus Observatory" description: "A published observation should carry its own history: which instrument made it, when, under which calibration, and every step since." url: https://observatory.global/stories/provenance/ publisher: Nexus Observatory Inc. updated: 2026-10-31 --- [Stories](https://observatory.global/stories/)System: Data provenance chain # From sensor to record A published observation should carry its own history: which instrument made it, when, under which calibration, and every step since. The web already has a vocabulary for that history1; transparency logs make it tamper-evident2. **Systems**: Signed readings, Transparency logs, Verifiable credentials **Toward 2030**: Post-quantum signatures **Figures**: 3, systems diagram, timeline to 2030, data story Go to the references **01** Systems diagram ## Every hop leaves a mark. The sensor signs its reading; the gateway forwards it; the edge checks the signature, stamps the time and appends an entry to an append-only log whose Merkle tree lets anyone verify that nothing was removed or rewritten2. The publication carries a link back to that entry. Compromise the gateway and see which readings still arrive verifiable. Scenario Figure as text: A provenance chain from signed reading to publication A four-tier diagram: sensors that sign, gateways, the edge with its transparency log, and publication and archive. - **Signing sensors** : Sensor 1, Sensor 2, Sensor 3 - **Gateways** : Gateway A, Gateway B - **Edge and log** : Edge admission, Transparency log - **Publication** : Publication, Archive 10 links. Scenarios: All hops trusted; Gateway A compromised. **02** Timeline to 2030 ## Words for where data came from. PROV describes entities, the activities that generated them and the agents responsible1. Verifiable credentials let an instrument or an operator present signed claims, such as a calibration certificate, that others can check3; content credentials do the same for images and media4. Figure as text: Provenance and transparency standards A timeline from 2013 to 2030 with PROV-O, Certificate Transparency 2.0, the post-quantum signature standards and Verifiable Credentials 2.0. 1. **2013-04** PROV ontology (W3C PROV-O). A W3C vocabulary for provenance. 1 2. **2021-12** Certificate Transparency 2.0 (RFC 9162). Merkle-tree logs with verifiable inclusion and consistency proofs. 2 3. **2024** Content credentials. Signed provenance manifests for media. 4 4. **2024-08** Post-quantum signatures standardised (FIPS 204, FIPS 205). Lattice and hash-based signatures published. 5 5. **2025-05** Verifiable Credentials 2.0 (W3C VC 2.0). Signed, machine-verifiable claims. 3 **03** Data story ## The cost of a signature. Signing every reading costs bytes. A classical elliptic-curve signature is 64 bytes6; the post-quantum lattice signatures standardised in 2024 run to thousands5, and hash-based ones larger still7. For a sensor sending 20 bytes, that is a design question, not a footnote. Figure as text: Signature sizes, classical and post-quantum A bar chart of signature sizes: 64 bytes for ECDSA P-256 and Ed25519, 2,420 to 4,627 bytes for ML-DSA, and 7,856 bytes for SLH-DSA-128s. | Scheme | Bytes | | --- | --- | | ECDSA P-256 | 64 | | Ed25519 | 64 | | ML-DSA-44 | 2,420 | | ML-DSA-65 | 3,309 | | ML-DSA-87 | 4,627 | | SLH-DSA-128s | 7,856 | Figure 1 Systems diagram **Sources reaching a sink**: 3 of 3 **Longest route**: 4 hops **State**: All hops trusted Figure 1. A provenance chain from signed reading to publication. A four-tier diagram: sensors that sign, gateways, the edge with its transparency log, and publication and archive. ## References 1. [PROV-O: The PROV ontology](https://www.w3.org/TR/prov-o/) . World Wide Web Consortium, 2013. 2. [RFC 9162: Certificate Transparency version 2.0](https://www.rfc-editor.org/rfc/rfc9162) . Internet Engineering Task Force, 2021. 3. [Verifiable Credentials Data Model v2.0](https://www.w3.org/TR/vc-data-model-2.0/) . World Wide Web Consortium, 2025. 4. [C2PA technical specification: content credentials](https://c2pa.org/specifications/) . Coalition for Content Provenance and Authenticity, 2024. 5. [FIPS 204: Module-Lattice-Based Digital Signature Standard](https://csrc.nist.gov/pubs/fips/204/final) . National Institute of Standards and Technology, 2024. 6. [RFC 8032: Edwards-curve digital signature algorithm (EdDSA)](https://www.rfc-editor.org/rfc/rfc8032) . Internet Engineering Task Force, 2017. 7. [FIPS 205: Stateless Hash-Based Digital Signature Standard](https://csrc.nist.gov/pubs/fips/205/final) . National Institute of Standards and Technology, 2024. ## Related stories [Horizon 2030: Post-quantum cryptography **Cryptography that outlasts the quantum computer** Data signed today may need to be trusted in 2040. Post-quantum standards were first published in August 2024, and governments have set dates for leaving…](https://observatory.global/stories/pqc-migration/) [System: Federation across agencies **Many agencies, one picture** No single agency observes everything it needs. Federation lets each keep its own systems and still share: common interfaces, common catalogues and common…](https://observatory.global/stories/federation/) [System: End to end **An observation grid, end to end** An observation is not a reading. It is a reading with a place, a time, a calibration and a path that anyone can follow back. 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