9 min read
CardanoWall is relaunching as a Proof of Existence service built on Label 309, an open, vendor-neutral record format for Cardano metadata. Hash, sign, seal, and share content, then verify it without trusting our servers.
Announcements
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Proof of Existence shows that exact data existed no later than a public timestamp — without publishing the private file itself. Here's how it works and what it does and doesn't prove.
The StandardGuides
12 min read
Label 309 writes a Proof of Existence into Cardano transaction metadata: a content hash first, plus optional signatures, sealed payloads, recipient key slots, and Merkle batches. Here is how each layer works and how anyone verifies it.
The Standard
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CardanoWall builds proofs in four layers: a plain hash timestamp, an optional signature, an encrypted sealed copy, and private delivery to specific recipients. You use only the layers a situation needs.
The StandardGuides
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A Merkle root lets one Label 309 record commit to thousands or millions of file hashes, then prove any single item later with a small inclusion proof — without putting every item on chain.
The StandardDevelopers
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Commit a private dataset snapshot to a hash or Merkle root and publish one timestamped proof. The data stays private; later you can selectively prove a file, row, or version was in the committed set.
AI & ProvenanceSecurity
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How to use Label 309 Proof of Existence to prove a document or discovery export existed by a public time and still matches its original bytes — and where that proof stops and legal process begins.
Compliance & Legal
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How a security team can timestamp and seal incident evidence as it is collected — a durable, independently verifiable timeline that proves what existed when, without publishing sensitive details.
SecurityCompliance & Legal
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Hash your source files, drafts, prompts, exports, or whole project folders and publish a timestamped Label 309 proof that they existed by a given time — without making the work public.
AI & ProvenanceGuides
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Your first Label 309 proof can be a hash-only record: hash a file, get a price quote from a gateway, publish the digest on Cardano, and keep the transaction hash. Here is the full workflow.
GuidesDevelopers
11 min read
A Proof of Existence shows that exact bytes existed by a public time. It does not, on its own, prove ownership, truth, authorship, who was first, legality, or admissibility.
The StandardGuides
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Both bind data to a point in time, but a Timestamp Authority roots trust in a named provider's key, while a Label 309 Proof of Existence roots it in public Cardano consensus. Here's how to choose.
The StandardCompliance & Legal
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C2PA describes the provenance of a media asset; Label 309 anchors a timestamped commitment to its bytes on Cardano. Here is what each one proves, and why most workflows want both.
The StandardAI & Provenance
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Sigstore signs software artifacts and logs the event publicly; Label 309 adds an independent blockchain time anchor over your whole release evidence. They solve different problems and work well together.
The StandardDevelopers
9 min read
OpenTimestamps is excellent for bare, Bitcoin-anchored timestamps. Label 309 adds a Cardano-native proof record with signatures, sealing, recipients, and Merkle batching — here is how to choose.
The Standard