NANO, formerly known as RaiBlocks, is a project initially conceived in 2014 by Colin LeMahieu, a Software Engineer based in Texas. The project is currently experimenting with Directed Acyclic Graphs (DAGs); an alternative data structure to the way blockchains are generally developed today. It attempts to provide a solution to one of the biggest risks currently faced by blockchain-based networks, which is the rise of immensely powerful quantum computers. Although still very theoretical, these supercomputers could enable hackers to attack blockchain based networks in the future. The NANO network offers quantum-resisting features by structuring its transactions using Directed Acyclic Graphs (DAGs), which are supposedly more resistant to quantum attacks. Transactions are posted on-chain as they occur by nodes of the network and linked with a signature system, thereby eliminating the need for mining and enabling free transactions. NANO also uses a Proof-of-Stake consensus mechanism to validate the blocks in its blockchain. In February 2018, 17 million units of NANO were stolen from BitGrail, an Italian cryptocurrency exchange. At the time, one unit of NANO was worth around $10, putting the total BitGrail loss at $170 million.
Bitcoin Gold was forked from Bitcoin in October 2017 by developer Martin Kuvandzhiev. The only thing that the project changed from the original Bitcoin source code was the consensus algorithm; from SHA-256 to Equihash, the consensus algorithm used to mine Zcash. This was seen as an unnecessary change by the general community, and only a small number of mining pools supported it. Kuvandzhiev used the rise of ASIC mining to justify the change, but the fork was still very much scrutinized. In November 2017, a report revealed that a hidden hard-coded algorithm was sending a 0.5% fee directly to Kuvandzhiev’s wallet along with the coinbase (block reward) transaction. Bitcoin Gold’s network value decreased significantly following the release of this report. That same month, bitcoin users looking to get a free bitcoin gold balance were targeted by mybtgwallet.com, an elaborate scam disguised as a wallet that stole its users’ private keys. Despite these issues, Bitcoin Gold continues to be a highly traded cryptocurrency due to its extensive exchange support.