☢ Radiation randomness beacon
放射線の乱数ビーコン
Every hour on the hour, this shop publishes one 256-bit random value made from the background-radiation particles its Geiger counter caught in that hour. Nobody, including the shop, can know it before the hour ends. Free, no sign-up.
毎時ちょうどに、その 1 時間に店のガイガーカウンターが拾った自然の放射線の粒から、256 ビットの乱数を 1 つ作って公開します。1 時間が終わるまで、店も含めてだれにも分かりません。無料・登録なし。
USE IT FOR YOUR OWN DRAW ・ 自分の抽選に使う
Announce in advance: “The winner is decided by the Raikiri beacon at 22:00 on 20 October (JST).” Write your list in a fixed order. After 22:00, take the value as a number, divide by the number of entries, and the remainder (0 is the first entry) is the winner. Anyone can check it on this page.
先に「10 月 20 日 22:00（日本時間）の雷切のビーコンで決めます」と告知し、応募の一覧を順番を決めて公開します。22:00 を過ぎたら、その値を数として応募の数で割り、余り（0 が 1 番目）の人が当選です。だれでもこのページで確かめられます。
value = "<the 64 hex digits>" winner = entries[int(value, 16) % len(entries)]
Several winners, or a list you would rather not publish in advance? The fair draw tool does it for you with the next particles. ・ 当選が何人もいるときや、一覧を前もって出したくないときは 抽選の道具 へ。
Run a fair draw ・ free公正な抽選をする（無料）LAST 24 HOURS ・ この 24 時間
| 410 | 11/05 15:00 | dd05a3b3678fabd26de24084125cd1f6fd9a0df326b58356bb0e037df148ad82 |
| 409 | 11/05 14:00 | 9f7e968fd7d99366f1239fd5f35edf81d54ae2f8253ddb9dcf21ea2131ad8b25 |
| 408 | 11/05 13:00 | e089cbd1d441427128baefe3326ea3182adedb92ef74d907762fa7c9f547615e |
| 407 | 11/05 12:00 | 6291c53efaf109c7abf9a1f45750b5f0a95ffe0336a3adc6b88ae30375309516 |
| 406 | 11/05 11:00 | aee162c50bff97ce42f9ba6348b98abd597ca39a943eb6a416cf3f612cac084a |
| 405 | 11/05 10:00 | 4c6bc0b6a17457d18075281b135b418fccb40c2475e282504e734e71d618c28a |
| 404 | 11/05 09:00 | 3ba05b08341f07f1f1e76f8c04e3f4f0f79a1fb99b42e5b1d8b279cb7840ac93 |
| 403 | 11/05 08:00 | 1b3c5fa8385e3b5cc34daf2f00e0f244c95918e9c7a471effb1f48227a82c379 |
| 402 | 11/05 07:00 | 92aba6d25bee488cdac6f5c0e569b39825251f60219f0f13bd86a2dfca5d2e14 |
| 401 | 11/05 06:00 | f97ce7c003308d413783e4fb5d55df6b1ee097903b1898836cf6bd468b295e21 |
| 400 | 11/05 05:00 | b1e76fdc57ff5b1505aaff14f4ddbf4cbb32da755f9e2c077e8c685d9b5c99bd |
| 399 | 11/05 04:00 | 995d67758fbfb043e9ee28182c073beea42aec240a31e19172df20e5d615c867 |
| 398 | 11/05 03:00 | 6a0b0168eb44f19028633e0c8b936c3190101d86da70f176b682a52d6aab3a85 |
| 397 | 11/05 02:00 | 7e951b5e9dc35ae59baca46fbcb9e1050fa50ad990f914f45d9d8610b89fcbe9 |
| 396 | 11/05 01:00 | 03f9f920af017a45a28780d7c6c2fb845682b977c34cec290325391f366689a3 |
| 395 | 11/05 00:00 | 031a53681eb0937bda6c0b3a97a2a696b78f550bcfdc8e256b30585a766c7ccc |
| 394 | 11/04 23:00 | 9ff28812780307d32d681359e7e506e5f7ba183c6f065793cfbd0d7a6b459dbe |
| 393 | 11/04 22:00 | 707c6d70fdd5171a2d12176923788dbbd44635ab956ea51a328ddfebc85dbcee |
| 392 | 11/04 21:00 | 8ecdf25c9e79d76297e2ff6cc29d2977664767c2ac6c534bfa6a7782d07b7aa6 |
| 391 | 11/04 20:00 | a8ff67853ec10572c9505c997e2bbb7be37005b45ba883beec16aeee74453b9b |
| 390 | 11/04 19:00 | c81161905af8d517d1ad7a7a12175c81bbf2496686a986c21c34439281f95746 |
| 389 | 11/04 18:00 | ec314bc33ab90dc426a29a6eda004b3df2d6ccc02b1fb188a9935f27fec11691 |
| 388 | 11/04 17:00 | c7468a2e8be87c2a063442fcb3fc1216bd703e48b6feb3c766502885616a2aa9 |
| 387 | 11/04 16:00 | adf0a14f3a7cbb044719c31af3e98ba75c210cfd6bb6600c1a1481f8dde0ab82 |
API
GET /beacon/latest · GET /beacon/at?t=2026-10-20T22:00+09:00 (the first value sealed at or after t) · GET /beacon/<n> · GET /beacon/feed.json. JSON, free, CORS open.
HOW IT IS MADE ・ 作り方
value = SHA-256(“raikiri-beacon-v1|” + number + “|” + sealing time (unix seconds) + “|” + previous value + “|” + the arrival times of that hour’s particles). Because each value includes the one before it, rewriting any past value would break every value after it. The particle times themselves are not published: their count is the hourly radiation reading this shop sells. If the counter caught fewer than 32 particles in an hour, no value is made for it (it is marked missing, never filled with computer random numbers). Values are public, so never use one as a key or a password.
値 = SHA-256（「raikiri-beacon-v1|」＋番号＋「|」＋閉じた時刻＋「|」＋1 つ前の値＋「|」＋その 1 時間の粒の時刻）。1 つ前の値を含むので、過去の値を 1 つ書き換えると、その先がすべて合わなくなります。粒の時刻そのものは出しません（数を数えると、店で売っている毎時の放射線の値になるため）。粒が 32 より少なかった時間は値を作らず「missing」とします（計算機の乱数で埋めません）。公開する値なので、鍵や合言葉には使わないでください。
The counter is a PocketGeiger Type 6 in a house in Japan, catching about two particles a minute. The same particles also draw the Geiger omikuji. · llms.txt