Cryptocurrency Nano

To agree on what transactions to commit (i.e., achieving consensus), it uses a voting system with weight based on the amount of currency an account holds.

Nano

Denominations
Code	XNO (formerly NANO, XRB)
Previous names	RaiBlocks
Precision	10−30 (raw)
Development
Original author(s)	Colin LeMahieu
White paper	"Nano – Digital money for the modern world"
Initial release	4 October 2015 (8 years ago) (2015-10-04)
Latest release	V25.1 "Daric" / 2 June 2023 (10 months ago) (2023-06-02)
Code repository	github.com/nanocurrency
Development status	Active
Written in	C++
Developer(s)	Nano Foundation
License	FreeBSD
Ledger
Timestamping scheme	"Open Representative Voting", a form of proof-of-stake
Hash function	Blake2
Issuance schedule	Captcha faucet (ended 20 October 2017; 6 years ago (2017-10-20))
Supply limit	133,248,297
Website
Website	nano.org

Nano was launched in October 2015 by Colin LeMahieu to address the Bitcoin scalability problem and was created to reduce confirmation times and fees. The currency implements no-fee transactions and achieves confirmation in under one second.

Colin LeMahieu started the development of Nano in 2014 under the name "RaiBlocks". A year later, RaiBlocks was distributed for free through a captcha-secured faucet. In 2017, after 126,248,289 RaiBlocks were distributed, the faucet shut down. This fixed the total supply to 133,248,297 RaiBlocks, after addition of a 7,000,000 RaiBlocks developer fund.

BitGrail hack

On February 9, 2018, an Italian cryptocurrency exchange BitGrail announced its hack and eventual shutdown. Users were prevented from accessing assets stored on the platform, which was collectively worth 17 million Nano. The victims then launched a class-action lawsuit against BitGrail owner Francesco Firano for recoupment, inside the Florence Courthouse. The exchange was ruled to be guilty in January 2019, as it was found to fail at implementing safeguards and reporting losses. The Italian police branch Network Operations Command (Italy) alleged the Bitgrail founder had conducted fraud. Nano prices had been around $10 prior to the hack and after the hack fell to $0.10.

Nano uses a block-lattice data structure, where every account has its own blockchain for storing transactions. It is the first cryptocurrency to use a directed acyclic graph data structure, by having a "block" consisting of only one transaction and the account's current balance.

Nano's consensus algorithm is similar to proof of stake. In this system, the voting weight is distributed to accounts based on the amount of Nano they hold; accounts then freely delegate this weight to a peer (node) of their choice.

If two contradictory transactions are broadcast to the network, indicating a double-spend attempt, nodes will vote for both transactions and broadcast their vote to the other nodes. The first transaction to reach 67% of the total voting weight is confirmed, while the other is considered invalid.^{[non-primary source needed]}