Data provenance

Verify data on the blockchain

Every study on Surdatics carries a SHA-256 hash of its data, anchored on the Internet Computer (ICP) blockchain. Only the hash goes on the blockchain, never the answers or anyone's details. Paste the hash below to see what it covers, when it was anchored, and whether the data still matches. No account needed, and you do not have to take our word for any of it.

The study's SHA-256 hash

One answer

Check one answer

What happens to an answer: The moment an answer reaches Surdatics, it gets a SHA-256 hash: a unique code computed from it. Change one word or one frame and the hash no longer matches.
Where the record lives: Once an hour, the new hashes are anchored on the Internet Computer (ICP) blockchain. Nobody can edit or delete that record, not even Surdatics. Only hashes go there, never the answers or anyone’s details.
How to check: Enter the answer code, or choose the video file. You see when it was hashed and the block where it was anchored.
Why it matters: Results cannot be quietly changed by anyone. Funders, regulators, journalists and examiners can check them for themselves. The blockchain record shows no answers and nothing about who gave them.

What the blockchain record proves

It shows

The dataset has not been edited, padded or trimmed since it was anchored.
How many responses it held when it was hashed.
What each person was paid for their answers, if the study paid: the payment record is part of the hash, not a note beside it.
When it was anchored, which anyone can check on the blockchain.
For a single answer: that it is unchanged since it arrived.

It does not show

That the questions were well designed, or the sample representative.
That a conclusion drawn from the data is correct.
What an answer says, or who gave it.
Anything about a dataset that was never hashed here.

How it works

A study's hash. When a study closes, the platform computes a SHA-256 hash over its questions and every approved response, in one fixed layout (spec surdatics-provenance-v3), including what each person was paid. Anyone holding the study's export can recompute that hash.

An answer's hash. When a submission is saved, each answer gets a SHA-256 hash over one fixed layout (spec surdatics-answer-seal-v1): the study, the response, the question, the answer, the time it arrived, the words or choices given, and for a recording, photo or file the SHA-256 of the file's own bytes, never its address. A random salt is mixed in, so a hash can never be used to work out a short answer such as “Yes” by trying each possibility. The salt is never published.

The record on the blockchain. A study's hash is written to the SURDA ledger on the Internet Computer as the 32-byte memo of a minimal transfer from Surdatics' recording wallet to itself. Answers are anchored once an hour: every answer hash of the hour becomes a leaf of a Merkle tree (surdatics-merkle-v1; a leaf is SHA-256(0x00 ‖ hash), a pair is SHA-256(0x01 ‖ left ‖ right), and an odd one out moves up unchanged), and only the root is written, the same way. The block number is the permanent address of the record. An hour with no new answers writes nothing.

Checking it yourself. Anyone can ask the ledger canister for the block with its public get_blocks call, without an account or a key: its memo holds the study's hash, or the root of the hour's answers. For an answer, the proof steps lead from its hash to that root, and your browser repeats them on this page. A file you choose is hashed on your device; only that SHA-256 is sent.

What it proves, and what it does not. A study's hash proves its data is unchanged since the study closed; an answer's hash proves that exact answer existed, unchanged, by the time its hour was recorded. Neither shows what an answer says or who gave it, or whether a study was well designed.