Why blockchain. What it does. What it does not.
Saroir uses the Bitcoin blockchain for one specific purpose: to prove that a piece of knowledge existed at a specific moment in time. Nothing else. No tokens. No wallets. No speculation.
The Problem We Are Solving
When someone contributes knowledge to Saroir, that contribution is moderated, accepted, and attributed to their permanent record. But how do you prove that the attribution existed on a specific date, without trusting any single institution to remember it correctly?
Databases can be altered. Servers can be taken offline. Records can be disputed. Institutions can be pressured.
A cryptographic timestamp anchored to the Bitcoin blockchain cannot. It is mathematical proof that a specific piece of content existed at a specific moment. No authority controls it. No court can alter it. No institution needs to be trusted for it to be verified.
That is the problem blockchain solves for Saroir. Precisely that, and nothing more.
How It Works, Step by Step
When a contribution is accepted on Saroir, the following happens in sequence:
The content is hashed
A SHA-256 fingerprint of the contribution is computed. This hash is a unique string of characters that represents the exact content. If even a single word changes, the hash changes completely.
A Verifiable Credential is issued
A W3C Verifiable Credential is created, signed with Saroir's Ed25519 cryptographic key. It contains the contributor's decentralised identifier, the contribution hash, and the date of acceptance.
The hash is submitted to OpenTimestamps
OpenTimestamps is a free, open-source protocol that bundles many hashes together and anchors them in a single Bitcoin transaction. Saroir pays nothing per timestamp. There are no fees, no vendor, no commercial relationship.
The Bitcoin block is mined
Once the Bitcoin network mines the block containing the transaction, the timestamp is permanent. The hash is now part of the most tamper-resistant public record in existence.
The proof is stored with the credential
The OpenTimestamps proof file is stored alongside the Verifiable Credential. Any contributor can download both. Any person anywhere in the world can verify them independently, without involving Saroir at all.
What This Means for Contributors
Your credential does not depend on Saroir continuing to exist.
If Saroir's servers went offline tomorrow, every contributor who had saved their credential and its timestamp proof would still be able to prove, to any employer, institution, or individual, that they contributed specific knowledge on a specific date. The proof is yours. It lives in a file. It is verified against Bitcoin, not against us.
This is what permanent attribution means in practice. Not a promise. A mathematical proof.
Why Bitcoin Specifically
Bitcoin was chosen because it is the longest, most computationally secure public ledger in existence. An attacker who wanted to falsify a timestamp anchored to Bitcoin would need to redo more cumulative computation than the entire network has performed since 2009. This is not a theoretical guarantee. It is an economic and physical one.
Other blockchains are younger, shorter, and less computationally secured. Some can be altered by coordinated actors. Bitcoin cannot be altered without a cost so enormous it has never been attempted.
For a platform whose entire purpose is permanent attribution, the choice of anchor matters. We chose the most permanent one available.
Why OpenTimestamps and Not a Custom Solution
OpenTimestamps is open source, free, and has been running since 2016. It was created by Peter Todd, a Bitcoin protocol developer, and has been audited extensively. It does not require a commercial relationship. It does not require Saroir to run any blockchain infrastructure. It bundles many timestamps into single Bitcoin transactions, which means the cost of anchoring is negligible and Saroir has no per-credential blockchain cost.
Most importantly: OpenTimestamps proofs are verifiable by anyone using open-source tools, without any involvement from Saroir. This is the property that matters. Trust in the timestamp should not require trust in the platform.
What Blockchain Does NOT Do in Saroir
We want to be precise about this, because the word "blockchain" carries a lot of noise.
Blockchain in Saroir is a timestamp witness. That is its complete role.
Verifying a Timestamp Yourself
You do not need to trust Saroir's word on any of this. Every accepted credential includes a downloadable OpenTimestamps proof file. To verify it independently:
- 1.Download the OpenTimestamps client from opentimestamps.org (open source, MIT licence).
- 2.Download your credential's proof file from your Saroir profile.
- 3.Run the verification command locally.
- 4.The client will confirm the Bitcoin block height, the block date, and that the hash matches the content.
No login required. No API key. No Saroir server involved. The verification happens between your computer and the Bitcoin network directly.
The Full Trust Chain
The trust in a Saroir credential comes from three independent layers, each verifiable without trusting the others.
W3C Verifiable Credential
Proves that Saroir issued this credential for this contributor for this contribution. Anyone can verify the issuer signature using Saroir's public key.
Ed25519 signature
Proves the credential has not been altered since it was issued. Any change to the credential breaks the signature.
OpenTimestamps proof
Proves the contribution existed at a specific moment in time. Bitcoin is the witness.
Together these three layers mean: this person contributed this knowledge on this date, and no institution, including Saroir, can alter that record retroactively.
Questions and Standards
Is this compliant with data protection regulations?
Yes. The Bitcoin blockchain contains only a SHA-256 hash, not personal data of any kind. The hash cannot be reversed to reveal the content or the contributor. No personal data is stored on any blockchain.
What standard does this use?
W3C Verifiable Credentials Data Model 2.0, published as a W3C Recommendation in May 2025. OpenTimestamps using Bitcoin. Ed25519 as defined in RFC 8037. These are open, audited, widely adopted standards.
Who controls the timestamp protocol?
Nobody. OpenTimestamps is open source. Bitcoin is a decentralised network with no single controller. Saroir has no privileged position in either.
Can Saroir revoke a timestamp?
No. The Bitcoin anchoring is permanent. Saroir can update or revoke a Verifiable Credential in its own records, but the timestamp proof that the original content existed at a specific moment cannot be removed from the Bitcoin chain.