B3Chain (ticker: B3C)
Conservative Bitcoin-Core-derived Layer 1 · B3PoW-Scratch v1.1 · testnet live
Official links onlyNOT us — do not useWhat is B3Chain?B3Chain Core is a fork of Bitcoin Core 30.2 that replaces Bitcoin's
SHA-256d mining algorithm with
B3PoW-Scratch v1.1 — a memory-hard
BLAKE3-based PoW with a 1 MiB on-chip scratchpad, 8 parallel lanes, and
2 048 sequential read–modify–write iterations per hash. Everything else
(UTXO model, 21 M cap, 10-minute target, 210 k halving, Bitcoin script,
P2P protocol, transaction format) stays as close to Bitcoin as we can
keep it. The block-identity hash is still SHA-256d, so explorer UX,
merkle proofs, and the wire protocol look identical.
The chain is at
testnet stage. There is no mainnet, no premine,
no ICO, no airdrop, no token sale, no founder reward, no developer
tax. Test coins (`tB3C`) have no monetary value.
Why a new PoW chain?Starting a new SHA-256d chain in 2026 means inheriting Bitcoin's idle
ASIC capacity on day one — any small mining outfit can centralise the
new chain before its first difficulty retarget. Choosing a CPU/GPU
algorithm trades that for botnet hashrate and unverifiable claims.
B3PoW-Scratch is one point on this trade-off curve. The explicit goal
is to make the most economical production miner a
small, low-power
FPGA card with on-chip memory (the reference is a Xilinx KU5P at
~10 W), and to bound the per-hash advantage of a custom ASIC by
making the algorithm memory-bandwidth-bound rather than compute-bound.
We do not claim "ASIC immunity" — none exists. The full argument is
in §1 and §6 of the whitepaper.
Key parameters| Field | Value |
| Base | Bitcoin Core 30.2.0 fork (MIT) |
| PoW algorithm | B3PoW-Scratch v1.1 (1 MiB scratchpad, 8 lanes, 2 048 iterations, BLAKE3 primitive) |
| Block-identity hash | SHA-256d (unchanged) |
| Block target | 600 s (10 min) |
| Difficulty algorithm | LWMA-3 (Zawy LWMA-3) |
| Halving interval | 210 000 blocks (50 → 25 → 12.5 → ...) |
| Supply cap | 21 000 000 B3C |
| Bech32 HRP | mainnet b3 / testnet tb3 |
| P2P port | mainnet 8533 / testnet 18533 |
| RPC port | mainnet 8534 / testnet 18534 |
| Stratum (testnet pool) | stratum+tcp://pool.b3chain.org:3333 |
| Testnet DNS seed | testnet-seed.b3chain.org |
| Testnet genesis hash | ebc117cd39760da3c8a3687484858e8ea2cfbc88990fb587957b4ba956a661c6 (v1.1.5) |
| Reorg-depth cap | 200 blocks (consensus-enforced) |
| Verifier budget | 50 ms / header (≪ 1 % of block interval) |
| Reference miner | B3Miner-1 — Xilinx KU5P FPGA card, ~10 W TDP |
| Premine / founder reward | none |
Read this firstTry it (testnet)Source- Core repo: github.com/b3chain/b3chain (MIT)
- Website repo: github.com/b3chain/b3chain-website (MIT)
- Reference Python miner: contrib/miner/b3chain-cpuminer.py
- Canonical Python reference: contrib/miner/b3miner-rtl/ref/b3pow_ref.py
- C++ consensus implementation: src/crypto/b3pow_scratch.{h,cpp}
- TypeScript pool validator: contrib/testnet/pool/src/lib/b3pow-scratch.ts
- SystemVerilog RTL: contrib/miner/b3miner-rtl/rtl/
- Hardware schematic (B3Miner-1): contrib/miner/b3miner-hardware/SCHEMATIC.md
All four PoW implementations are CI-gated against a single set of
consensus vectors at
src/test/data/b3pow_consensus_vectors.json.
Build from source (required)We do
not distribute prebuilt wallet binaries on Bitcointalk or via third-party GitHub accounts. Build
b3chaind yourself from the official repo:
git clone https://github.com/b3chain/b3chain.git
cd b3chain && git checkout b3chain-main
mkdir build && cd build
cmake .. && cmake --build . -j$(nproc)
./bin/b3chaind -chain=test
returns the three operator seed nodes; your node syncs automatically.
How to participate[list=1]
- Run a node. Build as above, then b3chaind -chain=test. Add yourself to doc/testnet-runbook.md §11 if you stand up a long-running peer — we will list community nodes.
- Mine. The reference Python miner is for protocol validation, not hashrate competition. Production miners run on the B3Miner-1 FPGA reference (RTL is open). A community KU5P bitstream is being assembled at contrib/miner/b3miner-rtl/sim/.
- Pool. You can solo-mine via getblocktemplate or join pool.b3chain.org:3333. Pool implementer contract: doc/stratum.md. Operator guide for standing up your own pool: doc/pool-operator-guide.md.
- Mirror the reference implementation. The Python reference is single-file and small. Independent ports (Rust, Go, C, Zig, ...) help us shake out spec ambiguities. Open a PR with parity tests against b3pow_consensus_vectors.json and we will list it.
- File issues. github.com/b3chain/b3chain/issues for bugs and feature requests. github.com/b3chain/b3chain/discussions for design RFCs.
- Security. Private email to security@b3chain.org (see security.txt). 90-day responsible-disclosure window (see CONTRIBUTING.md §10). Do not post unpatched-vulnerability details on this thread.
Roadmap (honest)- Now (testnet phase): B3Chain testnet is live with three seed nodes, a public Stratum pool, faucet, explorer, and a status monitor. Four PoW implementations are CI-gated to a shared vector set. The whitepaper, formal SPEC.md, 51 %-attack analysis, and threat-model docs are published.
- Next (mainnet candidate): external security audit (RFP package at doc/audit/; auditor not yet contracted), reproducible-build pipeline (Guix/Docker, SBOM, Sigstore signing), benchmark suite hardware run, IACR ePrint preprint submission, third-party miner integrations (cpuminer-multi, BFGMiner). Date: TBD. We will not name a mainnet date until the audit is contracted and the testnet has soaked under load for several months.
- Audit publication: all audit reports are intended to be published verbatim, with response notes, before mainnet activation. We do not pre-launch under embargo.
- Things we are deliberately not promising: a mainnet date, a price, a listing, an ICO, an airdrop, a yield, an "ecosystem of partners". B3Chain is engineering work; everything in this paragraph is in scope for other people to do, not us.
Disclaimers- This is testnet only. There is no mainnet B3C coin in circulation. Anyone selling a "B3C presale token" or "early-access allocation" is a scammer. The only official domain is b3chain.org. Impersonators may fork our GitHub tree — see the pinned advisory at issues/4.
- No unofficial binaries. Do not download "B3Chain wallet" .exe files from typosquat GitHub accounts (notably b3cblockchain). Build from github.com/b3chain/b3chain only.
- No premine, no founder reward, no developer tax, no investment vehicle. B3Chain is a software project, not a security offering. We are not your investment adviser; this thread is not a solicitation.
- Audit not yet contracted. The C++, RTL, and TypeScript implementations are reviewed in-tree and parity-tested against the Python reference, but no third-party audit firm has been engaged yet. The audit RFP is at doc/audit/RFP.md.
- Bug bounty (testnet only at launch). Critical bugs in the testnet PoW pipeline are payable in testnet B3C (tB3C, no monetary value) at launch — we are deliberately not paying mainnet bounties for testnet bugs. A treasury-funded mainnet bounty kicks in at mainnet launch. Scope and amounts: security/bug-bounty.md.
- Calibrated language. We do not use the words "ASIC-proof", "permanently decentralised", "unhackable", "revolutionary", "moonshot", or "quantum-resistant" to describe B3Chain. The README, code-of-conduct, and whitepaper say what we do claim, and the threat model says what we don't.
Maintainer contact- Project email: hello@b3chain.org
- Security only: security@b3chain.org (RFC 9116 security.txt)
- Code of conduct concerns: coc@b3chain.org
- GitHub: github.com/b3chain
- Real-time chat: Discord and Matrix are being stood up — invite link will be edited into this thread when ready (see doc/outreach/DISCORD-MATRIX.md for the planned channel layout).
- This thread: preferred for protocol-level discussion. We read every reply for the first 12 hours and most replies after that. Please don't DM the maintainers' personal accounts on Twitter/Telegram with operational questions — file an issue or post here.
Posted by the B3Chain maintainers. The text of this post is also tracked in the repository at doc/outreach/BITCOINTALK-ANN.md — pull requests welcome if anything has gone stale.
