Quizchain

The day after the book quiz ran out its clock, AoiNakamoto shrank the format to one question and called it a chain. Block 1 went up on r/bitcoinpuzzles on April 7, 2019: 7 mBTC, two answers to pick from, and the post tells you the right one. The hard part was supposed to be somewhere else.

How block 1 works

The answer is given, the address isn't

Pick b), "Satoshi is an anonymous cypherpunk and the first one to succed building private Internet cash." (the typo is in the original and in the hash, so leave it alone). Append the last three characters of the author's favorite Bitcoin address, SHA-256 the string, feed the hex to Ian Coleman's BIP39 tool as entropy, and take the first address at the bottom.

The favorite address is the whole puzzle, and the post only says "good luck finding" it. The author's solution comment says it was "apparent from my posting history": 1AndrewYangForPresident2o2o6zmPzd, a vanity address for the 2020 campaign, so the tail is Pzd. Same hobby horse as the book quiz, which was about Yang's book.

It was broken at first

The post carries an edit: "I messed up. This quiz as posted was not valid." The wording of answer b) got fixed after people had already started, so one commenter found the right address in the author's history, tried its last three characters and got nothing. Hard to blame them. Seven minutes after the author posted the solution, another player showed a screenshot and said they'd had it anyway.

What the quizchain record carries

A WIF from the thread, entropy without a phrase

export const quizchainBlock1 = bitcoinPuzzle({
  id: "quizchain/1",
  address: p2pkh("16NLaozWwi4JSTRMnMfi3oCkBjXBWVFgYR", "3ae1b60c6a83290db2e9c228413750d96be80116"),
  sourceUrl: THREAD,
  startedAt: "2019-04-07 03:31:37",
  status: Status.Solved,
  pubkey: compressed("028a941c0effd36b57654b9bf871817384f5bd06286cebe73096191bc3584acef3"),
  key: wif("L58cp8Ex3RsTsiKaaeodmu7SetzDzqQkzfX3bAtjdtmu4KbTpUzp").entropy(
    "50611e63a52089bc14e38becb1ad8880be6ba8f4aff0e64223f3dbd740adc1b7",
    source(SOLUTION, "SHA-256 of answer b) with the last three characters of the address appended"),
  ),
  prize: 0.007,
  transactions: [funding(/* … */), claim(/* … */)],
});

The author printed the SHA-256 and the WIF, not the mnemonic, so the record has no seed phrase and no derivation path. It keeps what the comment said. Put the hash through the BIP39 tool at m/44'/0'/0'/0/0 and you get that WIF, which is a check anyone can run, not something the thread wrote down.

Six hints, all the author's, in the order the post reads. The solution string and the favorite address hang off the two hints they answer, sourced to the solution comment, and the first hint's confirmation points at the 2023 Wayback capture of the thread.

Where the address comes from

The post never prints an address. It prints the funding transaction, and that transaction sends exactly 700,000 satoshis to 16NLaozWwi4JSTRMnMfi3oCkBjXBWVFgYR. The published WIF derives the same address, and the spend exposes the public key on the record.

Timing, from the chain: funded at 03:31:37 UTC, solution comment at 05:35, swept at 05:39:30 for 672,314 satoshis. The key had been public for four minutes by then, so the chain can't tell you whether the player with the screenshot or a fast stranger did it. The record says solved and names nobody.

One of the seven comments was already gone when the Wayback Machine took its only capture in 2023, so the post, the edits and the six that survive also live in the repo as an archived reading copy with a screenshot.

Numbered like b1000

quizchain/1, and 1, "1" and "quizchain/1" all resolve. The number is the block, the way the author counted them: "Stay tuned for block 2 of this chain." Later blocks get the next numbers, not a new collection each.

The Quizchain puzzle records