joachim

Who this is

A byline on the CryptoHack blog. In November 2020 CryptoHack wrote up their run through the Ledger Donjon CTF, and joachim's name is on several of the posts, among them the one this record comes from and a much nastier ECDSA side channel task written with esrever.

Scissors Secret Sharing was worth 100 points, so the easy end of the CTF. You get the twelve words of a BIP39 seed, just not in order, and a Bitcoin address to hit. Twelve factorial is about 479 million orderings, the checksum throws out most of them for free, and what's left you derive and compare. Not clever, just correct, which is the best kind of CTF solve.

What the record says

Two facts, the two write-ups. It's a CTF task, not a bounty, so the "prize" was points on a scoreboard, and the puzzle record says so by not recording one.

The record

solver: party("joachim", {
  key: "joachim",
  kind: PartyKind.Person,
  about: "CryptoHack writer who solved the BIP39 task of the Ledger Donjon CTF 2020 by brute forcing the word order.",
  facts: [
    fact("Wrote the CryptoHack write-up of Scissors Secret Sharing: a brute force over the ordering of twelve BIP39 words.", "https://blog.cryptohack.org/bruteforcing-bitcoin-bip39-seeds-donjon-ctf-writeup", { date: "2020-11-24" }),
    fact("Co-wrote with esrever the CryptoHack write-up of Projective Signatures, …", "https://blog.cryptohack.org/ecdsa-side-channel-attack-projective-signatures-donjon-ctf-writeup", { date: "2020-11-24" }),
  ],
}),