United Bitcoin (UBTC)UBTC
A December 2017 fork with 8 MB blocks and smart contracts, linked in the press to Jeff Garzik, that distributed coins only to addresses that had moved recently and was declared discontinued in early 2019.
The wiki's angle: United Bitcoin is where the SegWit2x story leaked into the airdrop era. A month after the 2x plan was suspended, the press tied one of the suspension letter's signatories to a fork that planned to put the balances of inactive wallets to work.[5][8]
Fork
The UnitedBitcoin client sets UBCHeight, and the UB fork block number, to 498,777[1]. That Bitcoin block has a header time of 18:19:12 UTC on 11 December 2017[2], which matches ZB's notice that UBTC forked at 02:19:12 Beijing time on 12 December[3].
Design
The README says UBTC keeps Bitcoin's total supply, block speed and halving time and the same proof of work, “only initial difficulty is lowered”[4]. It adds SegWit and 8 MB blocks and a new smart-contract system, and cites Qtum as a technical reference for contracts on a UTXO model[4].
Who was behind it
Bitcoin.com News reported on 14 December 2017 that Jeff Garzik, Bitbank Group's Songxiu Hua and Bloq chairman Matthew Roszak had launched the project[5]. The replies in the ANN thread appear under the heading “Launched in Silicon Valley on Dec 12 by Jeff Garzik”[6]. This wiki has not found a statement from Garzik himself, so his exact role is unverified[5].
Distribution
The ANN thread explained that holders received UBTC automatically only if they held bitcoin at block 498,777 and had made an outgoing transaction between blocks 494,000 and the fork, with a second phase for outgoing transactions up to block 502,315[6]. Bitcoin.com News reported that the team planned to use the balances of inactive addresses, with 30% for “influential communities” and 70% as reserves for fiat-pegged tokens[5].
End
The first post of the ANN thread was rewritten to say that UnitedBitcoin “failed to gain traction and discontinued early 2019”[7]. The exact date is not given, so the lineage map ends the line at the start of 2019 as an approximation[7].
References
- primaryUnitedBitcoin src/chainparams.cpp (UBCHeight 498777) [archived]
- primarymempool.space, Bitcoin block 498,777 (header time 2017-12-11 18:19:12 UTC) [archived]
- primaryZB exchange, notice that UBTC and SBTC were distributed, 12 Dec 2017 (ChainWhy archive, Chinese) [archived]
- primaryUnitedBitcoin README, GitHub UnitedBitcoin/UnitedBitcoin [archived]
- secondaryBitcoin.com News, “After Segwit2x Failed Jeff Garzik Reveals ‘United Bitcoin’”, 14 Dec 2017 [archived]
- primaryUnitedBitcoin ANN thread, replies of 11–12 Jan 2018 on phase 1 and phase 2 distribution [archived]
- primary“ANN: UnitedBitcoin - UBTC - Launched in Silicon Valley on Dec 12, 2017”, Bitcointalk topic 2607140 (OP united-bitcoin, last edited 21 Oct 2023) [archived]
- primaryMike Belshe et al., “Segwit2x Final Steps”, bitcoin-segwit2x mailing list, 8 Nov 2017 (Wayback Machine copy)