kTimesG's Phy Challenge

June 5, 2026. Bitcoin had its worst week since 2022, and kTimesG answered with a puzzle. Same kTimesG as the 80-bit challenge, different game. This time there's no range to search. The post promises "no loose ends, no hashing."

What's in the first post

Three things, and the author keeps saying that's all you need.

A text that sounds familiar. It's the abstract of the Bitcoin whitepaper with words swapped. "Electronic cash" became "modular values". Timestamps became "spacestamps", proof of work became "phylo-based proof-of-equivalence". Then a news headline and the line about a puzzle for everyone.

A Base64 string under it. That's a signed message signature, and it signs the whole text above it.

And a picture, 2048 by 2048. Grey emojis in a spiral around one golden Bitcoin coin. Hands, faces, a cat, a key, a padlock. All in greyscale, except the coin.

The prize showed up two weeks later

On June 21 the author came back: there's a prize "as of today", and one character is missing from the second code. Plus a PGP message, with "the password's already mentioned." The same evening, 800,000 sats landed on a native SegWit address.

Nobody had posted that address yet. Where does it come from?

The cat ate a J

The Base64 came out at 64 and a half bytes, and a signed message signature takes 65. People tried E, A, H. Someone decoded the PGP hint and got told "Congrats on decoding the puzzle hint. But it's not the missing char."

On July 29 NotATether posted "It's J." With the J in front, the signature verifies against the whole signed text, no trailing newline. It recovers the public key 02425afd…6650eb and the address bc1qrpn28qa82uyjg37dvsz3w7wpm3kpdea957nm9p. The funded one.

kTimesG fixed the post the same day. The explanation is the best line in the thread: "My cat is not part of this puzzle, yet somehow he managed to create the J incident." Ouch. Three days of building and checking the puzzle, and the cat got the last word.

Later someone doubted the address. The author's answer was short: "Why would you think the address is wrong, since the signature verifies?"

A signature that looks wrong on purpose

Decode the Base64 and look at s. 23 zero bytes, then 9 bytes of data. A random signature never looks like that. Somebody built this one.

So what does the post really hold? Everyone in the thread got stuck around here. NotATether ran Kangaroo over almost the whole 80-bit range. Nothing. The author's verdict: "no idea where it was ever hinted anything about using Kangaroo." The data speaks for itself, apparently.

The hints since

kTimesG doesn't hand out much. The record keeps 18 hints, the author's own plus two from other players. The ones people keep quoting:

• July: "the hints are already inside-out", and everyone is "stuck at the ASCII 8 cat incident".
• September: a meta clue, gvonys fhelucrM kbZ, to "wake up or confuse even more your LLMs".
• Skin tones are part of it. Paint every emoji default yellow and the answer holds only "if you already know that the image was redrawn."
• "The smart approach can find the correct solution in 4 milliseconds."
• And on September 23, a post that just says "This is a hint."

Four milliseconds. Not a GPU farm, not a week of Kangaroo. Whatever the trick is, it's small. Is it hiding in plain sight?

What the Phy record carries

export const phyChallenge = puzzle({
  id: "phy",
  chain: "bitcoin",
  address: "bc1qrpn28qa82uyjg37dvsz3w7wpm3kpdea957nm9p",
  sourceUrl: OP,
  startedAt: "2026-06-05 19:15:46",
  pubkey: compressed("02425afdd1716149faf414b6fdb96d5e7afc8ce42496042f4df559c80a7c6650eb"),
  prize: 0.008,
  hints: [/* the author's posts, the missing J with its answer, two from the thread */],
  transactions: [funding(/* 800,000 sats on June 21 */)],
  assets: assets({ puzzle: "puzzle.png", sourceUrl: PICTURE, digests: [digest(/* … */)] }),
});

The address comes from the signature

No post by the author ever spelled out the address. It comes from the signed text, and anyone can check it with keys_message_recover from @agntn/keys. Feed it the post and the signature with the J, plus the = padding the post leaves off. Out comes 02425afd…6650eb and the funded address. Feed it only the last line and some other address comes out. That's the whole proof, and the record keeps the public key it gives.

The same hint, twice

The June 21 post looks different today. When kTimesG fixed the J, the sentence about the missing character got struck through. The record keeps the original wording, with a June 29 capture as confirmation. The J itself is the hint's answer, credited to NotATether.

No technique yet

Nobody published how the puzzle works, so the record names no technique. Guessing one from the thread would be the kind of LLM essay the author keeps asking people to stop sending. Once a solution is out, it gets one.

The Phy Challenge record

puzzle({
  chain: "bitcoin",
  address: "bc1qrpn28qa8…a957nm9p",
})