Open research project · 2026
Bitcheque is an experimental proof-of-work blockchain. Print your cheque book once, offline and split across two printers, so neither printer ever sees a whole cheque. After that you can sign and send from any computer without trusting it. Open source under the MIT licence.
A device can be tampered with before it reaches you, or changed by an update. Any design that keeps your key on one device can fail that way. Once your book is printed, Bitcheque keeps the key off every device.
One clean, offline computer and USB printers.
Copy or scan the cells your digits point to.
Any computer can broadcast it.
About 20 minutes offline, then register from any computer. Two hours later your account number is final.
On a clean, offline computer, make your seed and print the book in two parts, on two printers. Save the public registration file, then switch everything off.
Take the registration file to any online computer and open it on this site. A minute or two of proof-of-work registers the book. The file holds no secrets.
About two hours later, scan the QR code on your sheet to see your final account number. Give it out to receive.
Write the recipient and amount, then copy or scan that cheque's 18 boxes on any computer. Your signed cheque is safe anywhere: no one can change who receives it or how much.
Enter the recipient and amount. The lit box in each column is the one to copy or scan from your cheque. Then broadcast.
Your boxes only fit this recipient and amount. Any computer can copy them and broadcast them for you, but none can change them.
Click a lit box to type its 12 words or scan its QR code. Or press Scan cheque to scan every box in one go.
No device sees your seed while you sign: the computer only gets that cheque's 18 boxes. The book is printed offline and the machines are switched off: a printer that never touches a network has nowhere to send it.
The chain stores one hash per cell and compares. No signature algorithm, no quantum shortcut: 2^128 classical, 2^64 sequential quantum steps.
The chain records which cheques are used. Lose the book, reprint from the seed. No counter, file or app state to back up.
The node is Rust with no dependencies, down to its own SHA-256. Consensus is small enough to audit line by line.
# build and test › cargo test --release # run a node that mines › bitcheque node \ --data chain.dat \ --listen 0.0.0.0:8731 \ --rpc 127.0.0.1:8732 \ --mine 1 # ask it anything over HTTP › curl 127.0.0.1:8732/height › curl 127.0.0.1:8732/account/1
Next to today's signing devices, assuming no human mistakes.
Air-gapped signer: for example SeedSigner. Bitcheque is stronger in how you sign; the other two run on a larger, long-proven network.
The questions people ask most about safety, loss and mining.
Yes, at the level NIST accepts. Forging a cell needs a SHA-256 preimage: 2^128 work classically, 2^64 sequential steps on a quantum computer. There are no elliptic curves in consensus.
Print on a clean, offline computer with USB printers, then switch everything off. A printer that never touches a network has nowhere to send what it printed. Your book is printed in two parts, ideally on two printers, so neither printer ever sees a whole cheque.
Reprint it from its seed, then use the reprint's last cheque (11) to sweep everything to a new book: that closes every unused cheque of the lost one. You only lose the account if the seed and the book are both gone.
It is a different trade. Bitcoin's weak point is the signing device and, later, quantum computers. Bitcheque's weak point is paper: whoever holds an unused cheque can make one move, so keep the book somewhere safe.
No. This is an experimental research project: we do not sell coins, and they carry no promise of value. Anyone who chooses to buy, sell or trade them does so at their own risk, outside our control. While the network is new the chain may be reset at any time.
Account numbers are short so you can copy them by hand, and they are handed out in the order books are registered. The newest few blocks can still be replaced by others, and then the same number could land on a different book. So a new number stays hidden for 100 blocks, about 100 minutes, until the order is settled for good. Scan the code on your sheet, or type its lookup code on the explorer, to see your number once it is final. The chain also refuses any cheque to a number that is not final yet, so nothing can be sent to it too early.
The chain is public: anyone can see every transfer of an account number. The node your browser connects to also sees your IP address and every account, lookup code and cheque you ask it about, so it can link your internet connection to your account. Use a node you trust, run your own, or connect through a VPN or Tor. This site needs no account, collects no name or email, and only remembers a few settings in your own browser.