Aristhor is an online platform that lets any user create, manage and publish blocksthor — private blockchains of testimony. It also provides the tools needed to cryptographically sign blocks, deposit public keys, call on warrantors, and publicly explore published blocksthor.

A blocksthor is a private, named blockchain made up of successive blocks, each cryptographically signed and linked to the previous one by its SHA-256d fingerprint. It thus forms an unalterable digital ledger: modifying a past block would invalidate the entire chain from that point on, making any tampering immediately detectable.

Each blocksthor is managed by a manager and can accommodate members according to a defined quota.

A blocksthor can be used in many contexts:

• Proof of precedence: demonstrate that information, a creation, or a document existed on a given date.
• Certified logbook: chronologically track interventions, work, or events.
• Compliance tracking: record quality controls, audits, or inspections.
• Intellectual property attestation: certify and timestamp the creation of a work, software, or design.
• Service guarantee: allow third parties to cryptographically certify the completion of a service.

No. Aristhor is a cryptographic traceability tool, not a legal service. The fingerprints and signatures produced constitute technical evidence of precedence and integrity, but do not have the legal value of a notarized deed or a bailiff's report.

Aristhor's interface is designed to be accessible. However, making full use of the platform — particularly to create signed blocks, generate PGP keys, or verify signatures — requires an understanding of the basics of asymmetric cryptography and the concept of a cryptographic fingerprint.

Go to aristhor.com and click "Create an account". Fill in your information (title, first name, last name, email), then validate your email address via the confirmation link received by email. You can then log in with your email and password.

The Blocksthor Maker is a tool that runs entirely in your browser, with no transmission of your sensitive data to a server. It lets you: generate PGP keys, create and manage blocksthor, calculate SHA-256d fingerprints, sign and verify signatures, and build Merkle trees.

No. Block creation, signing, and fingerprint calculation all happen locally in your browser via the Blocksthor Maker. Aristhor only receives the data you explicitly choose to publish or save on the platform (blocksthor name, fingerprints, public keys, warranties…).

The SHA-256d fingerprint is a cryptographic digest of 64 hexadecimal characters calculated from a block's content and the fingerprint of the previous block. It uniquely identifies a block and guarantees the immutability of the chain: the slightest modification to a block completely changes its fingerprint and invalidates all subsequent blocks.

The short format lets you refer to a fingerprint in abbreviated form by combining its first and last characters, separated by a dash -. For example, f7-4d means: the fingerprint starting with f7 and ending with 4d.

This format is accepted in Aristhor's fingerprint search engine and is shown in blocksthor record titles as a quick visual reference.

The zero-genesis block is the first block of any blocksthor. Its SHA-256d fingerprint constitutes the blocksthor's permanent reference: an absolute, immutable identifier that never changes, whatever the future evolution of the chain (added blocks, updates…).

No, by design. The very nature of a blockchain is to be immutable: modifying a past block would invalidate its fingerprint and, through chaining, all subsequent fingerprints. This is precisely the property that guarantees the evidentiary value of the blocksthor.

A warranty is a cryptographic attestation submitted by a third party (the warrantor) regarding a specific block of a blocksthor. It is signed with the warrantor's private key and contains: the fingerprint of the guaranteed block, a merkle root fingerprint, the warrantor's signature, the fingerprint of their public key, and the date.

Any Aristhor user with a deposited public key can become a warrantor for any block of a blocksthor, after being invited by its manager.

Aristhor uses standard OpenPGP asymmetric cryptography. Your private key — known only to you — is used to sign blocks and warranties. It must never be shared or uploaded to a server. Your public key — freely distributable — allows anyone to verify your signatures.

You deposit your public key on Aristhor. It is identified by its key fingerprint (40 hexadecimal characters). You can choose whether or not to make it visible in public searches by fingerprint or by email.

You choose exactly what you make visible. Three independent options are available:

• Public visibility of blocks: shows all of the blocksthor's blocks on the public record (requires public search by fingerprint to be enabled).
• Public search by fingerprint: makes the blocksthor findable by its fingerprint via public search.
• Public search by email: makes the blocksthor findable by your email via public search (requires public search by fingerprint to already be enabled).

From a blocksthor's record, the "Post to Mastodon" and "Post to Telegram" buttons appear as soon as you have configured your Mastodon access token or your Telegram Chat ID in "My account". These buttons are available to both the manager and the members of the blocksthor.

• Mastodon: set up a token with the write:statuses scope from your instance's developer preferences.
• Telegram: get your personal Chat ID via @myidbot, or a group/channel ID via @getidsbot, after adding the Aristhor bot there.

Blocks already signed remain valid and verifiable, since they were signed with your old key — signatures are permanent. However, you will no longer be able to add new signed blocks or submit new warranties with that key.

You then need to:

1. Revoke your public key on Aristhor (it remains visible but is marked Revoked).
2. Generate a new key pair via the Blocksthor Maker.
3. Deposit the new public key on Aristhor and enter its replacement key in the revocation record.

Account deletion is available from "My account" > "My settings". It is immediate and permanent: all your personal data is deleted. Publicly published blocksthor and warranties may persist depending on the settings chosen.

Aristhor only sees what you send it. Block content is created and signed locally in your browser via the Blocksthor Maker, without passing through our servers. Aristhor only stores the fingerprints, names, publication settings, and public keys that you voluntarily save on the platform.

Your full blocks are only visible on Aristhor if you have enabled the "Public visibility of blocks" option. Otherwise, only the fingerprints are accessible.

Likewise, the source files that produced the fingerprints inserted into your blocksthor — documents, images, files of any kind — remain entirely on your own device. Aristhor never has access to them: only the SHA-256d fingerprint calculated from these files passes through and is stored on the platform.