Use cases
Have your close ones testify: real cases anyone can check
Aristhor freezes a file (photo, video, contract…) in a blocksthor, then has identified people, the warrantors, attest to what this file represents. Each use case below is real and anyone can check it.
Case #1 · Sport · Private
The feat nobody believes: the SPORTIVA blocksthor
Above the Serre-Ponçon lake, in the French Hautes-Alpes, Alpha, a paraglider pilot, performs "infinity tumbling": his wing spins around him and, each time he passes the vertical, he ends up upside down, held by centrifugal force. He takes the opportunity to… read his newspaper.
Photo taken by the on-board camera, above the Serre-Ponçon lake. The original file is the one of block #2 of SPORTIVA.
1. The scene: a photo taken on board
The photo was taken by a camera fixed to Alpha's gear. Nobody was holding it, it was on board. It freezes the exact moment the pilot passes above his wing, newspaper open.
The problem: such a picture looks impossible. Photo editing? Artificial intelligence? The photo alone proves nothing, and neither does the pilot's word alone.
But that day, his family and friends were there and saw the figure. They are the ones who will testify.
2. How it works: a fingerprint, then signatures
The diagram shows the two stages: Alpha freezes the photo in his blocksthor, then his close ones warrant it.
Alpha manages his SPORTIVA blocksthor: the photo is frozen in block #2, his close ones' warranties are grouped in block #4.
Fingerprint With the Blocksthor Maker, Alpha computes the SHA-256d fingerprint of the photo on his computer. The photo is never sent: only its fingerprint, 64 characters, goes into his blocksthor.
Block #2 The fingerprint is signed with Alpha's private key and inserted in block #2 of his SPORTIVA blocksthor. Each block contains the fingerprint of the previous one: changing the photo or a block would break the chain.
Call for warrantors Alpha creates a call for warrantors for block #2 and invites his father, his mother, his sister and friends who were there that day.
Warranties Each warrantor writes a warranty ("I was there…"), signs it with their own private key and links it to the fingerprint of block #2. A warrantor can also refuse, giving a reason.
Block #4 The warranties are grouped: the fingerprint of each one becomes a leaf of a Merkle tree whose root is written in block #4. Block #2 is now "warranted" by block #4.
3. Seven witnesses who commit their signature
The 7 warranties of block #2, saved in block #4 of SPORTIVA.
The sceptic no longer has to take the pilot's word for it: to doubt the photo, they must assume that seven identified people all lied when signing.
Seven people warranted block #2: six close ones who were there that day, and Alpha himself. Each one signed with their own key, and the fingerprint of their public key is in their warranty.
« I was indeed there, so I confirm that this impressive photo was taken without any trick or artifice. The photo just freezes the movement at the moment the pilot passes the vertical of his paraglider wing, ending up upside down, held by centrifugal force. »
« I was there and I confirm: this photo perfectly matches the frozen reality. The pilot was indeed passing the vertical of his wing while reading his newspaper. »
« I am Alpha, the pilot, so of course I warrant that this photo was taken without any trick above the Serre-Ponçon lake in the Hautes-Alpes, France. »
4. What anyone can check
The photo has not changed by a single byte: download the original file, recompute its SHA-256d fingerprint in the Blocksthor Maker and compare it with the one of block #2.
The 7 signatures are genuine: load the warranties file in the warrantors tab of the Blocksthor Maker, each signature is checked with its warrantor's public key.
No warranty was added, modified or removed: the Merkle tree of the warranties gives back exactly the root written in block #4.
SPORTIVA is a real blocksthor: a sequence of signed blocks, each holding the SHA-256d fingerprint of one or more files (paragliding and tumbling photos, warranties…), never the files themselves. Download them below, recompute their fingerprint on your computer and compare it with the block's: if they match, the file hasn't changed by a single byte since it was inserted.
Files inserted in the blocksthor
The files whose fingerprint each block holds, to download and check for yourself
▸ How do I check a fingerprint on my computer?
macOS or Linux, in a terminal opened in the folder of the downloaded file (SHA-256d = SHA-256 applied twice):
Or without a command line: drop the file in the hash tab of the Blocksthor Maker, which computes everything in your browser. Compare the result with the Merkle root of the block.
This block holds 3 files: their fingerprints, in this order, are the leaves of a Merkle tree whose root alone is written in the block. The Merkle tree file lets you redo the calculation (Merkle tree tool of the Blocksthor Maker).
LISEZ-MOI - README - Aristhor.com
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FR
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Message de confirmation concernant ces deux fichiers photos :
« Ces photos sont bien toutes réelles et réalisées sans trucage. »
Explication méthodologique : un arbre de Merkle incluant le présent fichier a été calculé et c'est l'empreinte racine de l'arbre qui a été insérée dans le bloc.
EN
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Confirmation message regarding these two photo files:
"These photos are all real and were taken without any manipulation."
Methodological explanation : a Merkle tree including this file was calculated, and the root fingerprint of the tree was inserted into the block.
Warranty block: 7 warrantors attested, each with their own signature, that the photo of block #2 is genuine. The fingerprint of each warranty is a leaf of the Merkle tree whose root is written in the block. The warranties file can be checked in the warrantors tab of the Blocksthor Maker.
Charlie Aristhor« J'étais bien présent et je confirme : cette photo correspond parfaitement à la réalité figée. Le pilote passait bien à la verticale de son aile tout en lisant son journal. »
Delta Aristhor« J'étais là et confirme donc que la photo est parfaitement conforme à la réalité que j'ai vue. »
Foxtrot Aristhor« J'étais bien présent et je confirme que l'image est conforme à ce que j'ai vu. »
Golf Aristhor« Je confirme cette photo d'Alpha dans ses oeuvres spectaculaires. J'étais bien présent et impressionné par la dextérité d'Alpha. La photo est parfaitement conforme à la réalité saisie et figée par l'objectif. »
Bravo Aristhor« J'étais effectivement présent et je confirme donc que cette photo impressionnante a été réalisée sans aucun trucage, ni artifice. La photo fige juste le mouvement au moment où le pilote passe à la verticale de son aile de parapente, se retrouvant à l'envers, maintenu par la force centrifuge. »
Echo Aristhor« Je confirme. La photo est vraie. »
Alpha Aristhor« Je suis Alpha, le pilote, du coup forcément je garantis que cette photo est réalisée sans trucage au-dessus du lac de Serre-Ponçon dans les Hautes-Alpes en France. »
Raw content of the blocksthor
All the blocks as saved, to copy or export then load in the Blocksthor Maker
6. What it proves, and what it doesn't
Proved: the photo file is identical to the one frozen in block #2, and seven identified people signed, each with their own key, that they were there and that the photo matches what they saw.
Not proved: Aristhor cannot guarantee that the warrantors tell the truth. It makes their testimony named, dated and impossible to change afterwards. For a feat, that is what turns a rumour into an established fact.
Your turn
The same principle works for a personal record, a first ascent in climbing, a swim crossing or a ski jump: a file, its fingerprint, and close ones who commit their signature.
Scene: Julien lends Sarah €3,000 for her flat deposit. She will pay back €250 a month for 12 months.
Block 1: the IOU as a PDF (amount, schedule, date), with its fingerprint. Sarah signs it as a warrantor: the debtor acknowledges the debt.
Warrantors: two mutual friends who were there when they agreed. They attest that the agreement exists, not that Sarah can pay.
Next blocks: each repayment is a new block (screenshot of the transfer). Julien signs it to acknowledge receipt.
Why it helps: if they disagree two years later ("I'd already paid you back €1,500"), the dated and countersigned chain settles it, without a notary for a small amount.
Scene: Marc lends his drone (€1,400) to his brother-in-law for a wedding.
"Departure" block: 6 photos of the drone's condition (scratches, serial number, battery level) and a video of it starting up. The borrower warrants the block: "received in this condition".
"Return" block: the same photos on return, warranted by the lender. If a propeller is broken, the lender refuses the warranty with a reason ("rear propeller broken"), and this refusal stays visible in the call.
Non-profit version: a reuse centre or a neighbourhood "tool library" (hammer drill, trailer, marquee) uses one blocksthor per item. Each loan adds a block, and the item's history becomes its maintenance log.
Scene: a student flatshare, 4 flatmates and a private landlord.
Block: photos and video room by room, saved on move-in day. The 4 flatmates and the landlord all warrant the same block.
Why it helps: everyone signs with their own key, even a flatmate who arrives 6 months later (new "move-in addendum" block). On move-out, the fingerprints are compared, and nobody can say "I never saw these photos".
Journalistic certification of a scene by the witnesses present
A concrete example: a flash flood in a valley, for example in the Var or the Cévennes after a Mediterranean storm. At 6:42 pm, a local resident films the bridge of the main road being swept away. Within the hour, the video spreads on social media, and comments cry "fake" or claim it is a recycled video from 2020.
Block: the original video (raw file, with its metadata), its SHA-256d fingerprint and a factual description (place, time, direction of the shot).
Warrantors: the 5 neighbours on the riverbank, the village's volunteer firefighter and the local councillor who came on site. Each one warrants: "I was there, this video matches what I saw".
In the newsroom: the regional daily's journalist receives the video and the link to the blocksthor. They check that the file's fingerprint matches, that 7 identified people warranted it, each signing with their own key, and that it was saved before it went viral. They can also contact the warrantors.
Why it is strong: the date proves it came first, the fingerprint proves integrity (no editing afterwards), and the number of witnesses makes the link between the image and reality credible. This is exactly what fact-checking struggles to establish today.
The limit to accept: the blocksthor does not prove that the warrantors tell the truth. It makes their word committed, named and dated. It is a signed testimony, not an automatic truth.
Scene: during a demonstration, a freelance photographer captures a disputed arrest.
Block: they save the raw series of 40 photos in a single block (Merkle root of all the fingerprints), before any editing or cropping.
Warrantors: two other photographers and an observer from an association (a civil liberties association, for example), who were at the same place.
Why it helps: if a single photo is published later, cropped, it can be proved to come from a complete series saved on the spot. This rules out accusations of selection or manipulation, and the lawyer or newsroom has a chain of custody.
Scene: a plasterer renovates a house. The client pays in instalments.
Blocks: at each stage (partitions up, joints taped, painting), a block with photos and the interim invoice.
Warrantors: the client, and the project manager or a neighbour as witness if the client is away.
Why it helps: in a dispute over a hidden defect ("the insulation was never fitted"), there is the photo of the insulation, warranted by the client before the partitions were closed. This is valuable for the ten-year building guarantee and for insurers.
Case #8 · Collective decision · Professional / non-profit
Meeting minutes or collective decision
Scene: the general meeting of a sports club, or an informal meeting of co-owners.
Block: the minutes as a PDF. With a TEAM, the group's members warrant the minutes, and from 51 people, the manager's two blocksthor can have as many warrantors as the TEAM has people.
Why it helps: no more "that's not what we voted". A member who disagrees refuses the warranty with a reason, which also records the disagreement. Group information is used to announce the upcoming call for warrantors, so that everyone is ready to warrant the decisions made.
Scene: the sale of a 2014 car to a friend of a friend for €6,500.
Block: the mileage on video (dashboard, engine running), the condition of the bodywork, the roadworthiness test and the transfer certificate.
Warrantors: the buyer and the mechanic who test-drove the car with them.
Why it helps: a "hidden defect" claim becomes much less vague, since the car's condition on the day of the sale is frozen and countersigned by the buyer.
