Rules of the solidarity lottery
Everything that decides a draw is public and verifiable.
How a draw works
1. Publication: prizes, date, ticket price in hours and euros (1 h = 20 €). 2. Commitment: before the first sale we publish seed_commit, the SHA-256 fingerprint of a secret seed. It is frozen: we can no longer change it. 3. Ticket sales: every ticket receives its own serial number and fingerprint. 4. Sales close: we publish merkle_root, the fingerprint of the complete ticket list. After that publication no ticket can be added, removed or altered. 5. Draw: the seed is revealed. Winners are derived only from the seed, the Merkle root and the ticket list — the same input always yields the same winners. 6. Prize delivery: each prize follows its rank, with a delay and delivery mode announced in advance.
Why this is provable, not just promised
The draw relies on a commit–reveal scheme and on a Merkle tree. Commitment: seed_commit = SHA-256(seed). Published before sales open, it makes the seed irrevocable without disclosing it. On draw day the seed is revealed: anyone recomputes its fingerprint and checks it matches the published commitment. Ticket list: merkle_root is the fingerprint of every ticket, sorted then hashed pairwise. Changing, adding or removing a single ticket changes the whole root. Draw: for each prize, the draw value is SHA-256(seed:root:rank) mapped to 0…1 and applied to the sorted list of tickets still in play. No local randomness, no Math.random, no human hand. On the live page, the “Recompute it yourself” button repeats that computation inside your browser, away from our servers, and compares the result with ours.
Why this beats a video stream
We do not broadcast camera footage. A video can be edited, reshot or swapped — and nothing lets you verify it beyond trusting whoever held the camera. Our draw is a deterministic show in the browser that every viewer can recompute. The drum does not spin “however the animator wants”: every rotation and every stop is computed from the revealed seed. The same draw looks frame-for-frame identical for every viewer in the world and in every replay. Rigging it is impossible: the smallest forgery instantly diverges from the commitment published before sales. That is why this stage is proof, where a video stream is only testimony.
Participation rules
• Open to adults according to the minimum age of their country, shown in the “Your jurisdiction” section. • A ticket is paid in Time Bank hours or in euros (1 hour = 20 €), by card (Stripe) or PayPal. • The number of tickets per person is capped; the cap is the one of your jurisdiction. • Each ticket includes 5 artwork creations; colours are always free; 5 extra creations cost 2.50 €. • A cancelled or refunded ticket is removed from the list before sales close and does not take part in the draw. • One entry = one chance: a winning ticket is removed before the next prize is drawn.
Prizes and delivery
Prizes are ranked. A prize can be instant (hours, participation level, credits), handed over in person, shipped, legally transferred (vehicle, property) or paid out by a partner. After the draw the winner is notified by e-mail with their serial number, and has the period stated on the draw page to come forward. Any obligations of the winner (declaration, fees, formalities) are detailed in the “Your jurisdiction” section. Prizes unclaimed within the period are reallocated to the purpose of the association, never redistributed outside the published rules.
Protection and data
Public: the ticket serial, its fingerprint, the verification code, the jurisdiction country, the revealed seed and the Merkle root. Never public: your name, e-mail, postal address, hour balance or payment details. The live stage never displays personal data, nor the number of tickets sold, nor the amounts collected. Sanctuary mode encrypts your documents on your device; the association cannot read them. Audit journals keep cryptographic evidence, not people.
Responsible play
A solidarity lottery is still a game of chance: taking part must remain an act of support, never a forced expense. • Set your limit before you buy, not after. • The per-person ticket cap protects you; it is not there to frustrate you. • On simple request to the association, your account can be excluded from ticket sales for as long as you choose. • If play becomes a burden, say so: support services exist in every country and are listed on the Contact page.
What if the organiser tried to cheat?
• Changing the seed after seeing the tickets → impossible: its fingerprint was published before sales and would no longer match. • Adding a friendly ticket after closing → impossible: the published Merkle root would change and anyone holding the list would see it. • Removing a winning ticket → same effect: the root no longer matches. • Replaying the draw until a favourable outcome → impossible: with seed and root fixed, the result is unique and reproducible by everyone. • Rigging the animation → pointless: the animation is computed from the same public numbers, and the “Recompute it yourself” button ignores our stage entirely.