Nxt

History

On 28 September 2013 Bitcointalk.org member BCNext created a forum thread announcing the proposed launch of Nxt as a second generation cryptocurrency and asking for small bitcoin donations to determine how to distribute the initial stake. On 18 November 2013 fundraising for Nxt was closed, with 21 BTC raised. The genesis block was published on 24 November 2013. It revealed that 1,000,000,000 coins had been distributed to 73 stakeholders in proportion to their level of contribution. The source code was partially released on 3 January. The full source code was released on 1 March 2014 under the MIT License.

Concept

Just as with bitcoin, the blockchain is at the core of this currency. But Nxt is written completely from scratch and has departed in several ways from existing cryptocurrencies. Most notably, in one of his founding statements, BCNext asked the community not to consider the NXT coin as the important part, but rather to create currencies on top of it - possibly devaluing the core currency.

Developer Accessibility

The core structure and the client features are aimed at facilitating external development.

Proof-of-Stake Consensus Mechanism

While bitcoin uses hashing power as proof for verifying transactions, Nxt works with the stake-size the user owns. Block authors are selected in a practically random manner, with greater amounts of stake increasing the likelihood of adding a block to the chain. While in the case of bitcoin the cost of investing in mining gear serves as an incentive not to attack the network, anyone seeking to attack Nxt would in the process necessarily reduce the value of their personal coin holdings. This effectively avoids the security issue of a miner gaining 51% of the hashing power and attacking the network.

Forging

Since Nxt has an unchanging coin supply, no new units are created for block rewards. Instead the transaction fees are passed on. After owning Nxt for about one day (1440 confirmations), the Nxt software will begin to contribute to the block generation process and can potentially earn coins for as long as an account is "unlocked".

At the moment Nxt is open to attack if any account has 51% of the total coin supply that is forging. As outlined in the founding statements future versions of Nxt will include "transparent forging", a process which allows the software to predict which accounts will forge upcoming blocks. This is basically done by iterating through all active accounts and seeing which one has the highest "hit". Transparent forging rapidly increases transaction processing, since the account that will forge the next block is known. Another benefit of this feature is that accounts that are due to forge, but do not, will be penalized by having their forging power temporarily reduced to zero. This raises the threshold for an attack to 90%. The Proof-of-Stake algorithm requires little computation and energy, and can run on smartphones and small devices like the Raspberry Pi platform.

Features

The core infrastructure of Nxt is complex. This adds risks as compared to the more lean bitcoin, but makes it easier for external services to be built on top of the blockchain.

Asset Exchange

A peer-peer exchange allowing decentralized trading of shares, crypto assets. Since the blockchain is an unalterable public ledger of transactions, the Asset Exchange provides a trading record for items other than Nxt. To do this, Nxt allows the designation or "coloring" of a particular coin, which builds a bridge from the virtual crypto-currency world to the physical world. The "colored coin" can represent property, stocks/bonds, commodities, or even concepts. Most of the assets available at the platform represent shares of cryptocurrency-related startups.

Data Storage

Arbitrary Messages enable the sending of encrypted or plain text, which can also function to send and store up to 1000 bytes of data permanently, or 42 kilobytes of data for a limited amount of time. As a result, it can be used to build file-sharing services, decentralized applications, and higher-level Nxt services.

Alias System

The Alias System feature of Nxt essentially allows one piece of text to be substituted for another, so that keywords can be used to represent other things – names, telephone numbers, physical addresses, web sites, account numbers or emails. This would for example allow for a decentralized DNS system similar to Namecoin.

Voting System

Allowing holders of the currency or Nxt-Assets to vote in a cryptographically proven and externally verifiable way. This can be used for future development decisions, or for shareholder voting. It can also be applied to public elections and community based decision-making.

Plugin Support

The standard Nxt client supports the installation of plug-ins. This makes it possible for external developers to add features or usability enhancements. The plug-ins are not contained in a sandbox.

Monetary System

Implemented in version 1.4.8, the Monetary System allows the creation of currencies on the Nxt blockchain. These coins are backed by a specified amount of NXT, which can be redeemed if necessary. The possible properties range widely - including different models of inflation, exchange and the use of Proof-of-Work as distribution system.

Multi-signature and Phased transactions

The latest client (1.5) supports a method (named Phasing for Nxt) for requiring specific conditions for executing a transaction. Such as approval of multiple accounts or the passage of an interval of time.

Nothing at Stake Attacks

It is proposed that one could attack any Proof-of-Stake currency with zero costs. There are several proposed attack vectors. These include attempting to build blocks in every fork in the network, because doing so costs them almost nothing and ignoring any fork may mean losing out on the block rewards that would be earned if that fork were to become the chain with the largest cumulative difficulty.

Distribution

Since Nxt had no mining phase, all initial units were released to 73 people through a one-time fund raiser via bitcoins, after the announcement of the NXT project in the bitcointalk-forums by its inventor BCnext.

User-generated passwords

To access an account, the user types a password or a passphrase from which a private key is calculated, unlike bitcoin, where private keys are typically stored in a wallet file and not directly visible to the user.

Local Economies

On 18 September 2015, Wall Street investor Brian Kelly announced he would be investing in the Nxt-based platform Drachmae, which has as its aim the revitalisation of the local economy of the Greek Island Agistri.