Development of Nano began in 2014 by Colin LeMahieu, under its original name of RaiBlocks, and was publicly announced in October 2015. Distribution of Nano began in October 2015 via a free public captcha-faucet that ended in October 2017, by which point 126,248,297 NANO out of the total supply of / 10³⁰ NANO had been distributed. The Nano Foundation, a non-profit software development company, started by Colin LeMahieu, reserved 7 million Nano dedicated to the continued development of the protocol. The remaining undistributed supply of 207,034,069 NANO was removed from the supply and sent to a burn address without the possibility of recovery. As a result, the maximum supply of Nano is 133,248,297 NANO. On January 31, 2018, Raiblocks rebranded to ‘Nano’ to better resonate with the public and mainstream audience, as well as remove any confusion around the pronunciation of Raiblocks.
BitGrail Exchange Hack
On February 9, 2018, BitGrail, an Italian cryptocurrency exchange, announced its shutdown, reporting unaccounted losses of 17 million NANO from its wallets, preventing users from accessing assets stored on the platform. Victims of the exchange hack sought recoupment through the Italian court system, and supported by the Nano Foundation, launched a class-action suit against the BitGrail exchange owner, Francesco Firano. In January 2019, the Court of Florence found Francesco Firano liable for the losses after discovering that the exchange had failed to implement any meaningful safeguards to ensure the safety of their customers’ funds and failed to report losses from as early as July 2017. As of December 2019, bankruptcy proceedings are underway.
Other notable events
On June 19, 2019, Kappture Labs announced they would be integrating Nano into their customer-facing payment terminals, publishing a whitepaper alongside explaining their rationale for choosing Nano over other cryptocurrencies including Bitcoin, Ethereum, and Ripple.
Design
Block Lattice
Instead of using a single, monolithic blockchain, Nano uses a block-lattice data structure, where every account has its own blockchain. This is a unique implementation of a directed acyclic graph, where a "block" is just one transaction, and each transaction contains the account's current balance. Furthermore, account-chains can only be updated by the account owner, which allows the account-chain to be updated immediately and asynchronously from the rest of the block-lattice, resulting in quick transactions.
Open Representative Voting (ORV)
To prevent double spending and Sybil attacks, Nano uses a voting-based consensus algorithm called Open Representative Voting. In ORV, every account can choose a representative to vote on their behalf, and these representatives remain online to vote on the validity of transactions they see on the network. Unlike delegated-Proof of Stake, anyone can be a representative, no funds are staked or locked up, users can remotely re-delegate their voting weight to anyone at any time, representatives do not earn transaction fees, blocks are not built or chosen, and representatives cannot censor or reverse transactions. All Nano transactions are individually and asynchronously voted on by user-selected representative nodes before being immutably and irreversibly confirmed. The novel block-lattice DAG architecture's ability to scale was stress-tested in January 2018. Nano developers achieved a sustained 105.75 transactions per second on the main Nano network, with a brief peak of 306 tps.
Criticism
Bitcoin core developer Gregory Maxwell criticized Nano's Sybil attack protection, but the Nano protocol uses balance-weighted voting by account holders to prevent this kind of attack. Adding more nodes to the network will not give an attacker more votes, because voting weight is determined by the sum of delegated Nano balances. >50% of the online voting weight would have to be delegated to the attacker.
